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Influence of weaning strategy on behavior, humoral indicators of stress, growth, and carcass characteristics

Influence of weaning strategy on behavior, humoral indicators of stress, growth, and carcass... Influence of weaning strategy on behavior, humoral indicators of stress, growth, and carcass characteristics †,1 † † ‡ Sharon Freeman, Matt Poore, Carrie Pickworth, and Mark Alley † ‡ Department of Animal Science, North Carolina State University, Raleigh, NC, USA; and Technical Service Veterinarian, Zoetis, Inc., Cary, NC, USA ABSTRACT: Weaning is one of the most stressful d of age). The A  and D calves were more active events a calf experiences in our current beef pro- than N calves in the first 2 to 3 d after weaning duction system. Its effects may include reduced but settled down to similar activity levels to N by feed intake, increased activity, slower growth, and the day 4. The A and D groups were more vocal increased susceptibility to disease. This study was than N during the same time frame. Cortisol and designed to evaluate weaning after a 7-d place- haptoglobin remained within normal reference ment of nose flaps at 7 mo (N , n = 40) and delay- ranges. Average daily body weight gain (ADG) ing weaning by 49 d relative to 7-mo weaning (D, was greater for D than A, who in turn had greater n  =  39) as alternatives to the industry standard; ADG than N during the first 42 d after A and N abrupt weaning at 7 mo of age (A, n  =  39). The calves were weaned (0.69, 0.54, and 0.37 kg/d for 4-yr trial utilized Angus and Angus X Senepol D, A, and N, respectively; P  <  0.01). All treat- steer calves. Calves were randomly assigned to ment groups graded Low Choice at harvest and weaning strategy after being stratified by dam exhibited similar efficiency of gain during growth parity (heifer/cow), hair coat phenotype (normal/ and finishing (P > 0.2). Based on ADG during slick), and body weight. Behavioral observations the 42 d after weaning, we recommend delaying were made on five steers per strategy group per weaning when available pasture and cow body year over the weeks surrounding weaning. Activity condition support this strategy. When conditions levels were determined by accelerometers worn on do not permit delayed weaning, abrupt weaning neck collars. Blood samples were obtained from may be the next viable option based on animal the observed cattle during the last 2 yr to deter- welfare concerns and increased handling to place mine haptoglobin and cortisol concentration. and remove the flaps. Nose flaps reduced vocaliza- Once weaned, the steers were followed through tion at weaning but resulted in less postweaning finishing and carcass characteristics obtained at ADG. Based on our data, we suggest that abrupt harvest. Twelve of 38 steers in the N group had weaning under the conditions of this study, is less sores in their nostrils from the nose flaps when the stressful than we perceive it to be, based on calf flaps were removed at weaning of A/N (237  ± 3 behavior. Key words: activity, behavior, carcass characteristics, hormones, weaning strategy © The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science. This is an Open Access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Transl. Anim. Sci. 2021.5:1-16 doi: 10.1093/tas/txaa231 Corresponding author: sfreeman@ncsu.edu Received June 23, 2020. Accepted December 18, 2020. 1 Freeman et al. INTRODUCTION In current U.S.  beef production systems, weaning (the separation of a calf from its dam) is perhaps the most stressful experience a calf will face. According to USDA-NAHMS (2010), 49.8% of calves are removed from the presence of their dams abruptly and relocated away from their farms of origin. Rarely is this traumatic event an iso- lated source of stress, since weaning is also often used as a convenient time to vaccinate, deworm, dehorn, and/ or castrate. Because all these routine husbandry practices can be stressful, their combin- ation into a single event can have deleterious effects on calves’ wellbeing (Weary et al., 2008). The behavioral response to weaning in calves is multi-faceted. Feed intake is often reduced as a result of several factors, including more time spent walking/seeking, exposure to novel feeds, and changes in social structure in the herd (Veissier and Neindre, 1989; Price et al., 2003). Reduction in feed intake leads to weight loss or slower body weight gain (Price et al., 2003). Weaning may result in de- Figure 1. Nose flap before (a) and after (b) insertion into the nose pression and/or aggression (Veissier and Neindre, of a calf to prevent suckling. 1989). In addition to behavioral changes, stress at weaning has been shown to alter the concentrations were, therefore, to 1)  characterize calf behavior in of a variety of humoral compounds as the weaned the weeks surrounding weaning; 2)  assess calf ac- animal copes with the stressor (Arthington et  al., tivity levels with the use of accelerometers during 2005). Among these are cortisol and haptoglobin. the same time period; 3) monitor changes in hapto- The stress caused by weaning can increase the globin and cortisol levels during weaning; 4) quan- susceptibility of calves to disease, especially bo- tify growth efficiency during preconditioning; and vine respiratory disease (Yates, 1982), which is ex- 5)  document any impacts of weaning strategy on tremely costly to the beef industry in the United feedlot performance and carcass merit. States. According to USDA-NASS, about 2 million head of cattle are placed in feedlots each month MATERIALS AND METHODS (USDA-NASS, 2018). An estimated 16.2% of these are treated for respiratory disease after their arrival The 4-yr trial (2013–2016) was conducted at (USDA–APHIS, 2013) at a direct cost of $23.60 Cherry Research Farm (CRF; Goldsboro, NC) per head or about $91.7 million per year. This does and Butner Beef Cattle Field Laboratory (BBCFL; not account for production losses or mortality; Butner, NC) with approval from the Institutional however, it demonstrates the impact stress-related Animal Care and Use Committee at North Carolina disease has on the industry. State University (protocols #13-081-A, #13-124-A, Strategies purported to reduce stress at weaning, and #16–152). such as nose flaps designed to prevent suckling while allowing physical contact with the dam (Figure  1) Animal Husbandry Birth Through Preconditioning, and delaying weaning to more closely adhere to a Including Treatment Assignment natural weaning time, are available; however, there has been little research to quantify the impact of Calves were born in winter to early spring these strategies on animal behavior, humoral re- (December–March), castrated at birth, and reared sponse, and performance beyond the precondi- on pasture at CRF at their dams’ side for an average tioning phase, including impacts on carcass merit. of 237  ± 3 d.  They received minimal concentrate Hypothesizing these strategies could result in meas- prior to weaning and had free-choice access to a urable reductions in stress-related behaviors and complete mineral supplement (supplied 16% Ca, increases in performance, the goals of this study 1.9% P, 11.4% Mg, 0.1% K, 1,002 ppm Cu, 35 ppm Translate basic science to industry innovation Comparison of three weaning strategies Se, and 113,500 USP IU vitamin A; Renaissance per treatment) received accelerometers (Actical®, Nutrition, Inc., Roaring Springs, PA) and water. Philips Respironics, Bend, OR), attached via neck Steer body weight (BW) was recorded and steers collars, as they passed through the handling facility. were vaccinated according to normal farm protocol The OBS steers were sorted out of the main herd (2  mL/steer SC, Vision 7 Somnus with SPUR®, and put in a 3.4 ha pasture with their dams, sep- Merck Animal Health, Omaha, NE; 5  mL/head arated from the remainder of the herd to facilitate SC, Bovi-Shield Gold®, Zoetis, Inc., Parsippany, observation. The D steers, including D OBS, and NJ) and dewormed (5 mg/kg body weight fendben- their dams were maintained with the main herd dazole, Safeguard, Merck animal Health, Omaha, until 7 d prior to their weaning day. Forage in both NE) 28 d prior to weaning (see Figure 2 for a time pastures was similar and consisted primarily of line of the trial). Thirty steers per year in years-1 to bermudagrass (Cynodon dactilon (L.) Pers.), crab- -3 and 28 steers in year-4 were selected and strat- grass (Digitaria siderograpta Chiov.), and dallis- ified by hair coat phenotype (assessed at birth to grass (Paspalum dilatatum Poir.). Mixed grass hay be slick or normal), dam parity (first calf heifer or or small grain baleage was offered to both animal cow), and BW (mean  =  254  ± 6.7  kg). They were groups when pasture became limiting. randomly assigned to one of three weaning strategy After 7 d, both OBS and non-OBS steers from groups. Strategies were traditional, abrupt weaning all three treatment groups had BW recorded (A (A, n = 39); weaning after placement of a nose flap and N 7 d preweaning), nose flaps were placed in for 7 d (N, n  =  40); or weaning delayed by 49 d N steers (both OBS and non-OBS), and steers and from the date A  and N were weaned (D, n  =  39). dams were returned to their respective pastures. Treatments A and N ran concurrently. At the end of another 7 d, all steers (OBS and The steers and their dams were maintained as a non-OBS, all treatments) had BW recorded, nose single herd until 14 d prior to weaning. At this time, flaps were removed from N, and A  and N calves because there were only 10 accelerometers available were placed into corrals (A/N OBS steers, alone, in and to create greater uniformity among the steers a small corral [14.6  × 17.7 m] and A/N non-OBS used to determine activity levels and behavior, the steers in a large corral [18.9 × 67.1 m] with weaned heaviest five calves from mature cows in each treat- heifers). Weaning was delayed by 8 d for A and N ment group, balanced for hair coat phenotype, in yr 4 as the result of flooding from Hurricane were selected for behavior observation (OBS) and Matthew. Some non-OBS N steers lost their nose activity level determination. Using similarly sized flaps prematurely each year (2, 1, 2, and 7 for steers also protected the smaller steers from poten- 2013, 2014, 2015, and 2016; respectively). All OBS tial, postweaning aggression by larger steers while steers kept their nose flaps for the duration of the they would be housed, postweaning, in a corral. observation period. All three groups of steers had BW recorded 14 d Weaned calves had ad libitum access to hay, before weaning of A  and N.  This was considered water, and trace mineralized salt. Grain (80.2% the actual start of the experiment and the day ground corn, 17.3% soybean meal, and 2.5% when steers designated for A  and N OBS (n  =  5 limestone; as fed) was offered each morning at Figure 2. Time line of the experiment for each year. Translate basic science to industry innovation Freeman et al. approximately 0750  h, increasing from 1.4 to disturbance to the cattle and to reduce variation 2.3  kg per head per day over the 3 d immediately created by multiple observers. Observations were after weaning. Grain offered was held at 2.3 kg per made on four consecutive days (Tuesday through animal throughout the remainder of the precondi- Friday). The observer watched for predesignated tioning period. Weaned, OBS steers remained in the behaviors that were considered key indicators of smaller corral for 7 d, after which the accelerom- stress or absence thereof. Categories were grazing, eters were removed and they were then turned in eating hay, standing still or walking slowly, suckling with the larger group of weaned cattle. All weaned or attempting to suckle, ruminating, lying down, cattle had BW recorded 7 d after weaning. and other behaviors (included drinking, groom- Dams of the A and N cattle were sent to a pas- ing, eating minerals, scratching, playing, aggres- ture out of sight of their offspring to accomplish sion, etc.). Individual vocalizations were counted. weaning of A and N treatment groups. The D steers Observations of each individual steer were made at and their dams were placed in a separate pasture least three times during each 10-min interval and an to await delayed weaning. Dam body condition for effort was made to make the observations without all three treatment groups was assessed on a scale disturbing the animals. of 1–9 (1 being emaciated and 9, obese) at weaning The second observation period for A  and N of A and N in 2013–2015. Flooding prevented safe began 6 d before weaning, and was as described assessment in 2016. previously, lasting 4 d. During this period, A steers At 42 d after the weaning of A and N groups, had accelerometers, only, and N steers had both ac- steers in all three treatment groups had BW recorded, celerometers and nose flaps, allowing us to watch D OBS received accelerometers (7 d preweaning), for behavior changes in both groups caused by the and were returned to pasture for preweaning obser- placement of the nose flaps relative to base week. vation. All 10 D steers (OBS and non-OBS) were This period was not present during the observation housed together to facilitate care, both on pasture, of D, since no animals wore nose flaps. before weaning, and in the smaller corral, after The final observation period for all treatment weaning. The delay period between weaning of groups began the day after weaning day. It also pro- A and N and weaning of D remained consistent to ceeded as described earlier with the exception that protocol (49 d) in 2016. Delayed weaning and re- new behavior categories were tracked. Categories cording of weaning BW for D took place 7 d after after weaning included eating hay, eating concen- the placement of the collars (49 d after weaning of trate, standing still or walking slowly, pacing, lying A  and N) and final BW for D steers in this phase down, rumination, and all other behaviors. Again, of the experiment were collected 7 d after weaning, individual vocalizations were counted. Concentrate when accelerometers were removed. was offered after 20  min of observation had been Following the weaning of D steers, the weaned completed (at approximately 0750 h). Observations cattle were preconditioned for 45  ± 7 d at CRF were made for four consecutive days as previously prior to being shipped to BBCFL for growing described. and finishing. During the preconditioning period, After all observations had been completed, calves were housed on pasture, received 2.3 kg grain individual steer behavioral observations were tal- mix (80.2% ground corn, 17.3% soybean meal, and lied by category within 10-min periods and then 2.5% limestone; as fed) per head per day and had totaled for each day of observation by animal. access to ad libitum hay, trace mineralized salt, and The total number of observations was calculated water. for each steer by totaling all observed behaviors for each day. Rumination was considered a simul- taneous behavior and not tallied in the total. (e.g., Accelerometry and Behavior Observations A calf noted as standing or lying could also be ru- Behavioral observations began the day after ap- minating. Only the standing or lying was tallied in plication of the accelerometers (13 d before weaning the hourly total). The “other behaviors” category for A and N, 6 d before weaning for D). The obser- was also not included in the tally because many vations made during the first observation period were very short duration and were for observation served as a baseline week since none of the steers purposes, only. Percentage of total observations were subjected to treatment. Observations were for individual categories, including rumination, collected over 10-min intervals for 1 h, three times was then calculated (e.g., Observations tallied per day at approximately 0730, 1130, and 1530  h. as “standing” in day/total observations in day × A  single person made observations to minimize 100 = % standing). Translate basic science to industry innovation Comparison of three weaning strategies Accelerometers were preprogrammed to begin (2016). Intra- and inter-assay CV for haptoglobin measuring activity at 0800 h on the day they were (respectively) were 2.17 and 3.43% in year 3 and placed on the steers (at least 1 h prior to the place- 3.18 and 4.38% in year 4. Cortisol was determined ment of the first collar in its host animal). The ac- as a single assay with intra-assay CV of 5.30 and celerometers were programmed to collect data once 4.98% in years 3 and 4, respectively. per minute (the longest interval available) to ensure battery life throughout the collection period. None Husbandry at the Growing/Finishing Facility of the collars/accelerometers became displaced prior to the end of the data collection period. Steer BW was recorded upon arrival at BBCFL. Once removed from the calves 7 d after weaning, Steers were quarantined on pasture for 28 d and accelerometry data were downloaded using asso- adapted to a corn silage-based, growing total mixed ciated software (Actical 3.10; Respironics, Inc., ration (TMR, see Table  1 for ingredient compos- Murrysville, PA). One device malfunctioned in ition and Table  2 for nutrient content). Following year-2 and its data was not included in the analysis. quarantine, steer BW was again recorded and the Animal activity output was expressed as “relative steers stratified by hair coat phenotype, weaning activity units” (RAU). Relative activity data was to- treatment, and BW for assignment to 3 pens (2.7 × taled for each day of observation. 9.4 m). Pens were equipped with Calan gate feeders (American Calan, Northwood, NH) which allowed only one steer access and so permitted determin- Blood Collection for Humoral Analysis ation of individual feed intake. Steers received the Addition of new faculty between years 2 and growing TMR ad libitum and had access to free- 3 facilitated the analysis of blood for cortisol and choice water. Daily feed was weighed into each haptoglobin. As a result, during year-3 and -4, steer’s feeder in the morning and residual feed blood samples were collected via jugular venipunc- assessed visually at the next morning’s feeding. ture using 3.8  cm × 18-gauge needles into 10  mL Feed offered was adjusted up or down to achieve Vacutainer® tubes (Beckton Dickinson, Franklin maximum residuals of approximately 5% of feed Lakes, NJ) containing Lithium Heparin. Two tubes offered. Residual feed was removed and weight per steer were collected on day –14, –7, –5, 0, +2, recorded at 2-week intervals unless excessive re- and +7 relative to weaning for A and N and at day sidual was present, risking spoilage and contamin- –7, 0, +2, and +7 for D.  Blood tubes were imme- ation of the fresh feed. In this case, residual was diately placed on ice and stored until processing. removed more frequently and feed offered adjusted Plasma was separated by centrifugation at 2.316 × g downward. for 30 min. Plasma was pipetted into plastic storage Once the steers had learned how to operate the vials, frozen, and stored at –10°C. Once all samples gates, steer BW was recorded on two consecutive for the year had been collected, they were shipped days to obtain start weight for the growing phase. on dry ice to the University of Florida, Range Steer BW was recorded every 28 d until day 84, Cattle Research and Education Center, Ona, for when 2-d consecutive BW was recorded in prep- determination of plasma cortisol and haptoglobin aration for the transition to the finishing phase. according to procedures described in Moriel et al. To accomplish transition without digestive upset, Table 1. Diet composition of feedlot total mixed rations (TMR) with standard deviations (SD) fed to steers weaned at 237 d age either abruptly or after 7 d nose flap placement or after a 49 d delay at 286 d or age Component, % of DM (unless otherwise indicated) Growing TMR Finishing TMR Basal concentrate mixtures Corn 34.2 81.2 Soybean meal 60.4 13.0 Limestone 3.6 1.6 TM salt 1.3 0.3 Rumensin 90, kg/tonne 0.5 0.2 Vitamin A, D, E; kg/tonne 1.4 0.4 Total mixed rations (SD) Corn silage, % as fed 86.6 (3.47) 13.4 (0.32) Basal concentrate, % as fed 33.5 (3.47) 66.5 (0.32) Translate basic science to industry innovation Freeman et al. Table 2. Nutrient composition of feedlot total mixed rations (TMR) with standard deviations (SD) fed to steers weaned at 237 d age either abruptly or after 7 d nose flap placement or after a 49 d delay at 286 d or age Component, % of DM (unless otherwise indicated) Growing TMR (SD) Finishing TMR (SD) Dry matter, % 39.4 (4.17) 71.2 (3.19) Crude protein 12.5 (2.48) 12.5 (1.19) ADF 19.3 (3.01) 8.1 (0.68) NDF 31.4 (4.09) 16.5 (1.46) Ash 4.7 (1.25) 3.4 (0.95) Ca 0.5 (0.16) 0.3 (0.05) P 0.3 (0.05) 0.3 (0.01) Mg 0.2 (0.04) 0.2 (0.01) K 1.1 (0.22) 0.7 (0.03) Na 0.1 (0.08) 0.1 (0.05) Fe (ppm) 259 (76.7) 178 (35.7) Mn (ppm) 52 (5.8) 29 (4.2) Zn (ppm) 66 (24.3) 53 (24.3) Cu (ppm) 26 (11.4) 16.7 (3.2) TDN 74.6 (2.44) 82.8 (1.12) NE lact 0.78 (0.03) 0.87 (0.01) TMR was shifted over 10 d to the finishing for - made. Marbling scores were assigned and final mulation (Tables  1 and 2), after which the cattle yield grades (YG) calculated [YG  =  PYG + (re- received the finishing diet ad libitum until the ma- quired REA – actual REA) * 0.3  + (%  KPH – jority of the group had deposited at least 1.25 cm 3.5) * 0.2]. of backfat. Steer BW was recorded on day 140 and day 141 and as they were loaded for shipping to Cargill Meat Solutions (Wyalusing, PA) for har- Statistical Analysis vest 8.5 ± 6.8 d later. Shipping weights were used Design for this experiment was a randomized, to determine dressing percentage and adjusted end complete block replicated over 4 yr. Data were weights. analyzed using Proc Mixed of SAS (SAS v.  9.4; Samples of TMR and feed ingredients were SAS, Inc.; Cary, NC). For all models, year was the collected twice each week and stored at –10°C random term and where appropriate, calf was used until after the cattle had been harvested. Samples as a repeated measure. Class variables included year, of feed refusals were taken each time refusals were dam parity, hair coat phenotype, whether the steer removed from feeders. They were also stored at was OBS or not, status of the nose flap at removal –10°C. All samples were composited into monthly (missing or present), OBS period, day of OBS, and samples and dry matter (DM) content determined treatment group. Steers from N whose flaps were (Shreve et  al., 2006; NFTA method 2.2.2.5). lost prior to weaning were not included in the ana- Daily feed dry matter intake (DDMI) was calcu- lysis. One OBS steer lost its flap prior to scheduled lated from total feed DM offered and total refusal removal date; however, not during observation, so DM removed: (Feed DM offered–Refused DM)/ his data was included. Two calves had inexplicably number of days. high (10 times higher than average) haptoglobin levels at one collection day each (one at weaning in Carcass Measurements year 3 and the other 2 d after weaning in year 4). Hot carcass weights were recorded at har- These data points fell outside the 99th percentile as vest and dressing percentage calculated. Trained determined by Proc Univariate of SAS, so they were graders from USDA assigned quality and pre- not included in the analysis. Any main effect which liminary yield grades to the carcasses based on returned a P-value greater than 0.2 was eliminated visual appraisal. After carcasses had chilled for from the model as was interactions that returned P at least 24  h, measurements of back fat (FAT); > 0.2. Final models included treatment, hair coat kidney, pelvic, and heart fat (KPH); and rib eye phenotype, OBS period, day of OBS, and the inter- area (REA, between the 12th and 13th rib) were action of period and day, where it was significant. Translate basic science to industry innovation Comparison of three weaning strategies Significance was defined as P ≤ 0.05 and a trend was small and would not have impacted the outcome of defined as 0.05 < P ≤ 0.10. While hair coat pheno- the trial. type did return significant differences for some Body weight among treatment groups did parameters, there were no significant interactions not differ at the trial’s initiation (Table  3) and between hair coat phenotype and weaning strategy. the treatment groups remained similar in BW Differences for hair coat phenotype will not be dis- through preconditioning and at shipment to the cussed in this paper. finishing facility. We also found few differences in ADG by the steers. We had hypothesized that N calves, deprived of suckling, would gain less RESULTS AND DISCUSSION BW than A  calves that had accessed to milk as a supplement to pasture and hay. Boland et  al. Birth Through Preconditioning (2008) and Enríquez et al. (2010) reported signifi- Cow body condition.  Cow body condition cantly greater ADG by control calves, destined scores at the weaning of A  and N were 5.5, 5.4, for abrupt weaning, than by calves wearing nose and 5.9 (SEM = 0.16) for 2013, 2014, and 2015; flaps in the period prior to weaning. Haley et  al. respectively, well within the 5.0–7.0 range recom- (2005) reported greater gain in control calves than mended for breeding beef cattle (Eversole et al., calves wearing nose flaps in one trial, but not in 2005). Adequate condition at this stage indicated another, similar to our findings. There was no de- that no harm would come to the cows by allowing layed weaning treatment group in any of these steers in the D group to continue to suckle be- trials. There is no clear explanation for variation yond the traditional weaning date used for A and in the ADG results in these experiments. It is pos- N.  Cows who reared A  calves had lower BCS sible that day-to-day variation in BW negated than cows who reared N calves (5.4 and 5.8, re- small treatment differences. Possible contributing spectively; SEM = 0.11, P = 0.01) and cows who factors to the differences in results between experi- reared D calves were intermediary (BCS  =  5.6). ments are management differences such as penning There is no clear explanation for these find- cattle as compared to leaving them on pasture or ings. Since all the cows remained within the re- moving them from one location to another at the commended range and differences were small, onset of the trial. however, the differences are not likely of any bio- During the 7 d following weaning of the A and logical significance. N groups, the D steers gained more than their Steer growth.  Steers were 209  ± 3 d of age at weaned peers (Table  3, P  <  0.01) while A  and N treatment assignment and did not differ by treat- gained at similar rates. This is not surprising since ment (P  =  0.72). Observed calves were older than the D steers were able to supplement forage with those not observed (212 vs. 206 d, P < 0.01). Since milk and they remained with their dams. Boland the heaviest calves were selected for observation, et  al. (2008) and Enríquez et  al. (2010) reported it is logical that they were also the older animals. greater ADG for abruptly weaned cattle as com- The difference, while statistically significant, was pared to those that had worn nose flaps. Haley et al. Table 3. Growth parameters among steer calves weaned abruptly (A, 237 d age), after 7 d nose flap (N, 237 d age) application, or after a time delay of 49 d (D, 286 d age) from birth until shipment to a finishing fa- cility with standard errors (SEM) Parameter A N D SEM BW* 14 d before weaning A and N, kg 260.4 263.8 263.2 5.5 BW 7 d before weaning A and N, kg 266.6 268.4 262.7 5.3 BW at weaning A and N, kg 275.7 278.1 273.3 4.7 BW 7 d after weaning A and N, kg 280.1 279.8 286.4 5.0 BW 42 d after weaning A and N, kg 302.5 285.2 293.1 4.8 BW at shipment to finishing facility, kg 321.4 317.3 314.1 4.8 ADG*: birth to weaning of A and N, kg/d 1.01 1.02 1.00 0.02 ADG: 7 d preweaning of A and N, kg/d 1.33 1.13 1.71 0.59 a a b ADG: 7 d postweaning of A and N, kg/d 0.61 0.31 1.86 0.26 b a c ADG: 42 d after weaning A and N, kg/d 0.54 0.37 0.69 0.04 a,b,c Values without common superscripts differ (P ≤ 0.05). * BW: body weight; ADG: average daily gain. Translate basic science to industry innovation Freeman et al. (2005) reported inconsistent results after weaning for cattle reported in the literature are variable but and suggested plain of nutrition being better in 1 yr fall within the range of 0.3 μg/dL (Hopster et  al., than the others which could have caused the differ- 1999) to 5.5 μg/dL (Doornenbal et  al., 1988). All ence in results. cortisol concentrations in the present study were At 42 d after weaning A and N, BW of all three within the normal range (Table 4). Mean cortisol in treatment groups remained similar; however, ADG D was greater (P < 0.01) than in A and N steers and varied (Table  3, P  <  0.01). The D group gained was greatest when baseline concentration was de- faster than A, which gained faster than N.  Haley termined, prior to weaning and observation. There et al. (2005) reported that in the period of 7–21 d is no clear explanation why this treatment group postweaning, calves that had worn nose flaps and would have elevated cortisol as compared to their abruptly weaned cattle gained similarly. Enríquez A and N peers. Doornenbal et al. (1988) reported et  al. (2010) reported similar gains for abruptly that serum cortisol increased from 3.85 to 5.49 μg/ weaned and calves that had worn nose flaps over dL as steers aged from 7.5 to 12.5 mo; however, there the 44-d postweaning period. Management differ- was only a 7-week age difference between the D and ences could possibly explain the difference between A/N calves so age difference may only account for a our results and those reported elsewhere. The small portion of our observed treatment variation. calves in both other trials mentioned were pastured Cortisol remained consistent within D steers over and received no supplementation while the weaned time; however, the A and N steers had variations in calves in our trial were housed in a drylot where cortisol over the course of the experiment. Cortisol they received hay and concentrate. While our calves was elevated in A at nose flap insertion and in both had been exposed to the hay previously, they had A and N 2 d after nose flap insertion as compared not been completely reliant on it and their experi- to baseline levels. Since the response was seen in ence with supplemental concentrate was minimal. both groups and concentrations were back to base- Additionally, 12 of 38 steers that had worn nose line levels at weaning, increased handling or the flaps had bloody sores inside their nostrils. It is pos- presence of the observer may have had an influence sible that soreness reduced feed intake. Incidence on cortisol in these calves, which as the trial pro- of nasal sores from the use of nose flaps has not gressed, had time to adapt to both handling and the been described in the literature so its frequency is observer. The D calves were handled at the same unknown. times as the A/N calves which could explain their Humoral indicators of stress.  Plasma cortisol lack of response over the baseline week. and haptoglobin are low in healthy, unstressed Haptoglobin is often undetectable in healthy cattle. Baseline cortisol reference concentrations cattle; however, research indicates reference Table 4. Concentrations of humoral stress indicators in steers weaned abruptly (A, 237 d age), after 7-d placement of a nose flap prior to weaning (N, 237 d age), or after a delay of 49 d (D, 286 d age) with standard errors (SEM) Humoral factor A N D SEM a a b Cortisol, μg/dL 1.90 1.58 2.37 0.14 a;x ab;xy b Baseline 1.70 2.07 2.70 0.28 yz yz Nose clip insertion 2.43 2.25 n/a 0.21 z z Nose clip + 2 d 2.56 2.41 n/a 0.21 xy xy Weaning day 1.84 1.54 1.93 0.28 ab;xyz a;x b Weaning + 2 d 1.90 1.30 2.43 0.28 ab;xyz a;x b Weaning + 7 d 2.17 1.43 2.44 0.28 b b a Haptoglobin, mg/dL 4.26 5.59 0.29 0.88 b;z b;z a;y Baseline 8.73 9.21 3.57 1.73 z y,z Nose clip insertion 7.89 7.53 n/a 1.73 y,z y,z Noseclip + 2 d 5.32 6.61 n/a 1.73 x,y x x,y Weaning day 1.80 1.21 ND* 1.83 b;x,y b;y,z a;x Weaning + 2 d 4.88 7.04 ND 1.83 a,x b;x,y a;x,y Weaning + 7 d 1.61 4.81 0.92 1.73 a,b Values without common superscripts differ between treatments within time (P < 0.05). x,y,z Values without common superscripts differ between times within treatments (P < 0.05). *ND: not detectable. Translate basic science to industry innovation Comparison of three weaning strategies concentrations of 0–20  mg/dL (Gånheim et  al., more consistent over the course of the experiment. 2003; Chan et al., 2004; Seppä-Lassila et al., 2013) Because we saw no consistent patterns of change for for healthy cattle. Haptoglobin has been shown to cortisol and haptoglobin and because of our small increase above baseline with the challenge of re- sample size, it is difficult to determine whether there spiratory disease (Godson et  al., 1996) with con- was a humoral stress response or not. centrations peaking (110 mg/dL) 8 d after infection. Steer relative activity and behavior.  The ac- At weaning, Arthington et al. (2003 and 2005) re- celerometer output is reported as RAU, which ported peak concentrations (2.4–14.9  mg/dL) 3–4 are an omnidirectional reflection the subject’s ac- d after weaning. While within the reference range tivity and energy expenditure. Robért et al. (2009) found within the literature, they considered the demonstrated accelerometers can successfully be increase they observed a response to the stress of used to accurately detect such activities as lying, weaning. Haptoglobin concentrations in our steers standing, and walking and that they are useful in remained within the reference range throughout monitoring circadian activity patterns of feedlot the trial (Table 4). For all treatment groups, hapto- steers (Robért et  al., 2011). Treatment and treat- globin concentrations tended to decline between ment by period and treatment by period by day baseline sampling and weaning. Only those in N interactions were detected (P  <  0.01). Calves as- had elevated haptoglobin at 2 d after weaning as signed to the D group had fewer RAU during the compared to concentrations on weaning day; how- week for determining baseline activity levels than ever, this may not have been the optimum time to calves assigned to either the A  or N treatments detect changes in this protein and it is possible (10,545 vs. 21,969 and 22,172 RAU, respectively; that had we been able to sample in the 3–4 d after P  <  0.01). The most obvious explanation for the weaning time period, elevations would have been difference is that by the time the accelerometers detected. were placed on the D calves (42 d after A  and Across all sampling times, the steers in the N were weaned), pasture was scarce and so they A  and N treatment groups had greater average spent more time at a hay feeder, where they were haptoglobin concentrations than D. The difference relatively still, than did the A and N calves, which was driven largely by the greater concentrations spent more time grazing and only relied on hay found in A and N at baseline and preweaning sam- when pasture diminished. This assumption is sup- ples since levels were similar among treatments at ported by a decline in RAU for the A and N calves weaning. One possible explanation is the greater over the course of observation periods 1 (Figure 3, time interval from preweaning vaccinations for baseline) and 2 (nose flaps placed). Day to day the D steers (70 d) as compared to A  and N (14 variation was likely influenced by weather. All the d); however, Arthington et al. (2013) and Rodrigues cattle were stationary during windy periods of et  al. (2015) found haptoglobin levels returned to heavy precipitation and such weather existed more prevaccination levels 3–6 d after vaccination. Based in some years than others and could have resulted on these findings, haptoglobin in our A  and N in less RAU for certain days. calves should have been at normal levels before the The greatest difference in activity levels were trial began. There is therefore no clear explanation seen over the first 4 d after weaning. Both the for the difference and the concentrations reported A  and D calves had significantly more RAU than for A and N were still within the range for healthy N (Figure  3, P = 0.03) on day 2. On day 3 and 4, cattle. Having a larger number of cattle could have D calves continued to have more RAU than N possibly given us additional insight. (P  =  0.02 and 0.06 for day 3 and 4, respectively) Haptoglobin levels responded to time within while A calves were intermediary in RAU and did each treatment (Table  4). For A  and N, levels de- not differ from either D or N (P > 0.15). By the clined from collection of baseline samples to fourth observation day after weaning, all treatment weaning, rose slightly by 2 d after weaning, and groups exhibited similar RAU. Weaned calves were then declined again to preweaning levels by 7 d housed in a corral and so had limited space for postweaning. Thompson et al. (2011) reported ele- movement. Had they been weaned in a pasture set- vated haptoglobin 10 d after weaning in calves that ting, RAU counts and treatment differences might had worn nose flaps for 7 d and in control calves as have been even greater; however, they probably well. This time frame was beyond that in our study would have followed a similar pattern over time. and beyond what was described in other research, Price et  al. (2003) reported calves weaned on pas- previously mentioned. Delay weaned steers’ hapto- ture increased their walking by 2.5 times over calves globin was undetectable by weaning and remained weaned to a drylot. Translate basic science to industry innovation Freeman et al. Figure 3. Relative activity of steers weaned abruptly (237 d age), after 7-d placement of a nose flap prior to weaning (237 d age), or after a delay of 49 d (286 d age). We are not aware of other published research N during the baseline week since calves were of where 3-dimensional accelerometers were used to similar age and all had similar access to suckling. record activity levels specifically associated with This pattern continued during the week of nose weaning; however, Haley et  al. (2005) placed flap placement, with A  suckling more frequently pedometers, which measure 2-dimensionally, on than N attempted to suckle (7.2 vs. 4.7%, respect- a subset of their experimental cattle and noted ively; P  <  0.01). Over this observation period, that the number of steps per day did not differ both groups suckled or attempted to suckle more between control and nose flap calves during the frequently than during the baseline week. The ob- baseline period. Once nose flaps were placed, the server reported several A  calves nursing from N nose flap cattle took about 2,000 more steps per dams during the nose flap period when N calves day than the control group. They reported on could not access milk and N calves persistently the day following weaning, the abruptly weaned trying to suckle. The increase in suckling and/or at- calves took over 17,500 steps more than the tempting to suckle by A calves could have been due calves that had been fitted with nose flaps. Both to the opportunity to obtain milk from multiple treatment groups returned to baseline levels of dams but this cannot be affirmed based on study steps per day by day 4 after weaning. Over the design. Suckling attempts by N calves tended to de- 8-d period surrounding weaning, their nose flap cline over the 4-d observation to 2.5% of observa- calves averaged 4,084 fewer steps than the con- tions (day 1 vs. day 4, P = 0.07). This is similar in trols. These results show similar activity patterns time frame to data reported in Hötzel et al. (2012) to those in our study. who saw suckling attempts decline 4–5  days after The objective of placing nose flaps is to prevent nose flap placement. suckling while allowing physical contact with the Walking or pacing the fenceline is a commonly dam. During the baseline period, A calves were ob- observed behavior in calves recently separated from served suckling and/or attempting to suckle more their dams. The calves in the present study exhib- than either N or D calves (Table 5, P < 0.01). Since ited this seeking behavior although it declined in older calves (D) would be expected to be closer to A and D over the course of the observation period natural weaning, the difference between A and D is (Table  5, P  =  0.07). On the first observation day, not surprising; however, there seems to be no ob- the A  steers paced more than the N steers and vious explanation for the difference between A and the D steers were intermediary, in agreement with Translate basic science to industry innovation Comparison of three weaning strategies Table 5. Behavior of steers weaned abruptly (A, 237 d age), after placement of a nose flap for 7 d (N, 237 d age), or after a 49-d delay (D, 286 d age) presented by treatment least square mean (LSM) or daily observa- tions with standard errors (SEM) Treatment Behavior (units) Observation period LSM or day no. A N D SEM b,x a,x a Suckling or attempt (% of observations) Baseline week LSM 4.8 2.8 2.3 0.7 b,y a,y Nose flap in LSM 7.4 4.7 N/A 0.7 b,y a,y Noseflap day 1 9.0 6.0 N/A 1.4 x xy Noseflap day 2 4.6 5.4 N/A xy xy Noseflap day 3 6.7 4.9 N/A b,y a,x Noseflap day 4 9.2 2.5 N/A Pacing (% of observations) Postweaning LSM 6.6 3.2 4.1 1.6 b,z a ab,y Postweaning day 1 18.8 2.8 11.7 3.5 y xy Postweaning day 2 7.2 2.1 4.2 x x Postweaning day 3 0 5.4 0.8 x x Postweaning day 4 1.1 2.4 0 x x x Vocalizations (count per hour) Baseline week LSM 3.3 2.0 1.0 1.5 x x Nose flap in LSM 2.9 3.5 N/A 1.3 c,y a,y b,y Postweaning LSM 20.6 7.3 14.4 1.5 c,y a,y b,y Postweaning day 1 46.5 12.8 39.3 3.0 c,y a,x b,y Postweaning day 2 26.8 6.8 13.9 x x x Postweaning day 3 6.1 5.5 3.4 x x x Postweaning day 4 3.1 4.1 0.9 y y y Eating forage (% of observations) Baseline week LSM 45.0 45.0 46.3 2.1 y y Nose flap in LSM 44.0 46.0 N/A 2.1 a,x b,x b,x Postweaning LSM 13.1 22.3 25.9 2.1 a,x b b Postweaning day 1 8.7 23.8 31.4 4.1 Postweaning day 2 12.8 21.1 23.2 Postweaning day 3 20.1 25.5 28.7 Postweaning day 4 10.9 18.6 20.1 b,x b,xy a Lying down (% of observations) Baseline week LSM 22.6 21.8 14.3 2.2 x,y x Nose flap in LSM 25.2 20.6 N/A 2.2 b,y b,y a Postweaning LSM 30.9 30.1 14.9 2.2 a,b Values without common superscripts differ between treatments within period (P < 0.05). x,y,z Values without common superscripts differ between periods or days within treatment (P < 0.05). pedometer measurements by Haley et  al. (2005). to weaning (Table  5, P  =  0.02). Nose flaps re- Pacing declined for A  and D over the first 2  days duced vocalizations compared to both A  and D after weaning. On day 3 after weaning, pacing ac- (P  <  0.01). All the calves had returned to pre- tivity was similar across treatments (P = 0.17). The weaning levels of vocalization by the third day observed pacing helps explain the pattern of the of observation, with N calves achieving prewean- RAU. We detected no overall treatment differences ing levels a day earlier than A  or D, suggesting for pacing behavior. they may have dealt with weaning anxiety more Vocalization in cattle is also often associated quickly. Haley et  al. (2005) also reported greater with seeking behavior when herd members are sep- vocalization counts on the second and third days arated from one another and with stressors, such after weaning from abruptly weaned calves as as hunger (Weary et al., 2008). Prior to weaning, compared to calves weaned following placement vocalization counts were similar among treatment of a nose flap. Vocalization counts for the control groups and low (Table 5; P > 0.15). Vocalizations calves were similar in magnitude to those in our were attributed, by the observer, to movement of study. Price et  al. (2003) used fenceline weaning feed or animals within sight of preweaning pas- instead of placing nose flaps. With this alternate, tures. Following weaning, vocalization counts in- 2-step weaning process, vocalizations were also creased dramatically. All three treatment groups reduced as compared to abrupt weaning. Again, had greater vocalization counts on the first day counts per animal per hour were similar in magni- of observation after weaning than they had prior tude to those in this study. Translate basic science to industry innovation Freeman et al. Cattle in the A and N treatment groups spent accepted it (P > 0.36). Time spent eating concen- more time grazing during the baseline week than trate was determined by pecking order within each those in D (33, 27, and 2% of observations, re- group rather than by treatment. Concentrate was spectively; P  <  0.01). As mentioned earlier, this cleaned up within 30 min. is likely due to changes in pasture forage avail- Calves from all three-treatment groups spent ability than to applied treatments. Conversely, D similar amounts of time lying down prior to cattle spent more time eating hay during the base- weaning (Table  5, P > 0.61). During the observa- line week than A  or N (44, 12, and 18% of ob- tion period after weaning, the D calves spent less servations, respectively; P  <  0.01). When grazing time lying down than either A or N calves, with the and hay observations were combined into “eating exception of the fourth day after weaning, when forage,” treatment differences before weaning dis- all spent similar amounts of time lying down. We appeared and all the cattle spent about 45% of had anticipated that A calves would spend less time their time eating forage (Table  5). This is similar lying down than N calves, after weaning, and that in magnitude to behavior reported by Price et al. D and N calves would follow similar patterns for (2003) prior to weaning. lying down. One possible explanation for what we Following weaning, the calves’ only forage observed is that the N calves, who paced less than source was hay. All treatment groups spent less A and seemed more at ease in the absence of their time eating forage postweaning than prewean- dams, may have been prone to lying down and that ing (Table  5; 18% vs. 45%, respectively; P  <  0.01). their behavior influenced their A  peers, since all Calves in the A  group tended to spend less time were housed together. These two treatment groups eating forage than either N or D (13% vs. 22 and ran concurrently and had been housed together to 26%, respectively; P = 0.06); however, the majority facilitate observation by a single observer from the of this difference was the result of the earliest part initiation of the trial and so they remained together of the observation period, since by the third day after weaning. Delayed wean calves were housed in of observation after weaning, there were no signifi- absence of other weaning strategy groups. Haley cant differences (Table  5). Haley et al. (2005) also et  al. (2005) reported that abruptly weaned calves reported less time spent eating among abruptly spent less time lying down than those weaned with weaned calves as compared to calves weaned after nose flaps, in contrast to our observations. Their nose flap placement. Boland et al. (2008) reported cattle were maintained on pasture rather than being that calves with nose flaps in place spent less time housed in a corral and this difference may have in- eating (grazing) than either control or calves sep- fluenced behavior. arated from their dams by a fenceline prior to re- We postulated that another possible influence mote separation from the dams. Following remote on lying down could have been environmental tem- separation of the dams, Boland et  al. (2008) re- perature. The Thermal Heat Index (THI) devel- ported that there was no further reduction in eating oped by Thom in 1959 is the basis for the Livestock time among calves that had worn nose flaps, while Weather Safety Index (WSI; LCI, 1970) which div- abruptly weaned controls and fenceline calves ex- ides heat stress risks into classes. Based on the WSI, perienced reductions in eating to levels below those THI between 23 and 26°C can reduce productivity of calves that had worn nose flaps, although the and THI between 26 and 29°C can pose danger to fenceline group spent more time eating than the animal wellbeing. Hahn (1999) states that ambient control group. Price et  al. (2003) also found that temperatures above 15°C can induce nominal per- fenceline separation prior to weaning reduced the formance losses in feeder calves gaining 0.8  kg/d. decline in eating time after remote separation. The Dry bulb temperatures during the 1130 and 1530 h results of Boland et  al. (2008) suggest that two- observation sessions after weaning were 22.3 and stage weaning with a fenceline separation may be 23.7°C for the A  and N calves, respectively, and a better alternative than nose flaps, since it reduced 13.1 and 14.3°C for the D calves (P  <  0.01). The the decline in time spent eating. A and N calves were also subjected to heat indices Upon weaning, it is common for producers of 25.5°C or greater on 3 of 4 observation days at to offer concentrate to calves to replace the nutri- both the mid-day and afternoon periods in each tion that had previously come from milk. We ini- year of the trial. The D calves, on the other hand, tially offered 1.4 kg per steer per d of a corn-based had less than 1 instance per year of heat index ex- concentrate and increased this to 2.3  kg per steer ceeding 25°C after weaning. Elevated temperatures per d over 3 d. There were no treatment differences and HI during the postweaning period for A and N in concentrate consumption and all calves readily may have caused these steers to rest more in shaded Translate basic science to industry innovation Comparison of three weaning strategies areas of the corral and to lie down in these areas three treatment groups was similar (Table  6, where the soil may have been cooler. The D steers P = 0.21). Weights of the three treatment groups would not have experienced the same need to cool remained similar through shipment to the harvest themselves. Mattachini et al. (2011) reported a nega- facility (P = 0.36) as did ADG (P = 0.78). Daily tive correlation between lying behavior in lactating DMI was also not affected by weaning strategy dairy cows and temperature-humidity index and (P  =  0.91). As a result, there were no differ- Heinicke et  al. (2019) reported increased activity ences in feed efficiency between the three treat- with decreased lying time. Cattle in these trials had ment groups (P  =  0.65). With the exception of access to shaded, free-stall housing; however, so ob- studies with early weaning, we are not aware of served behaviors may not be comparable to those other studies that have followed groups of calves of cattle provided with minimal shade. A clear ex- of similar age weaned by different weaning strat- planation for our observations is not apparent. egies through harvest. Thompson et  al. (2011) Observed rumination frequency was similar took ultrasound carcass measurements; however, (P  =  0.37) across treatments prior to and dur- they do not report feedlot gain or feed consump- ing nose flap placement. Calves were ruminating tion. Our data suggest that weaning strategy did at about 15% (SEM  =  3.4%) of observations. not impact growth beyond the backgrounding Following weaning, all treatment groups seemed period (42 d after weaning A and N) when calves to ruminate more with some days having observa- are of similar age. tion frequencies of approximately 20%; however, there were no overall treatment differences in ru- mination behavior with frequency means of 19.0, Carcass Characteristics 17.8, and 14.4% for A, N, and D, respectively, after Weaning strategy had minimal impact on car- weaning. Enriquez et al. (2010) reported treatment cass characteristics (Table  7). Carcass weight, x day interactions for rumination where rumination back fat thickness, and KPH fat percentage were increased for control calves on day 2 following not different among treatments. The D steers weaning before returning to preweaning levels on had slightly smaller ribeye area than A  steers day 4. Fenceline weaned calves had greater rumin- (P  =  0.04) with N steers being intermediary for ation frequency on the day after weaning and re- this characteristic. All three-treatment groups turned to preweaning frequency on day 4 after had ribeye area that was similar to current in- weaning. dustry average of 89.7  cm and fell within the optimal range for the food service sector for Growing and Finishing cooking time and tenderness (77.4–96.6  cm ) re- Following their quarantine, the steers began ported by Dunn et  al. (2000). These results are the growing phase of the trial and BW of the in agreement with those of Myers et  al. (1999) Table 6. Growth and finishing characteristics of steers weaned abruptly (A, 237 d age), after 7-d placement of a nose flap prior to weaning (N, 237 d age), or after a delay of 49 d (D, 286 d age) with standard errors (SEM) Parameter (units) A (SEM) N (SEM) D (SEM) BW* at start growing phase, kg 353 (4.2) 349 (5.1) 343 (3.9) BW at end growing phase, kg 505 (5.4) 507 (9.4) 494 (5.0) BW at end finishing phase, kg 610 (7.2) 594 (7.0) 601 (8.9) BW at harvest, kg 629 (7.4) 622 (9.3) 615 (7.3) ADG* growing phase, kg/d 1.8 (0.05) 1.8 (0.08) 1.8 (0.04) ADG finishing phase, kg/d 1.4 (0.05) 1.5 (0.09) 1.4 (0.05) ADG overall, kg/d 1.6 (0.03) 1.6 (0.04) 1.6 (0.03) DMI* growing phase, kg/d 10.7 (0.18) 10.5 (0.23) 10.5 (0.17) DMI finishing phase, kg/d 10.4 (0.29) 10.7 (0.33) 10.5 (0.28) DMI overall, kg/d 10.5 (0.18) 10.6 (0.23) 10.5 (0.18) Gain:feed, growing phase 0.17 (0.003) 0.17 (0.006) 0.17 (0.003) Gain:feed, finishing phase 0.14 (0.004) 0.14 (0.006) 0.14 (0.003) Gain:feed, overall 0.15 (0.002) 0.16 (0.003) 0.16 (0.002) *BW: body weight; ADG: average daily gain; DMI: dry matter intake. Translate basic science to industry innovation Freeman et al. Table 7. Carcass characteristics of steers weaned abruptly (A, 237 d age), after 7-d placement of a nose flap prior to weaning (N, 237 d age), or after a delay of 49 d (D, 286 d age) with standard errors (SEM) Parameter A (SEM) N (SEM) D (SEM) Dressing percentage, % 60.0 (0.30) 60.1 (0.37) 60.5 (0.29) Adjusted end weight, kg 636.6 (8.3) 626.8 (10.3) 618.8 (8.1) Back fat, cm 1.37 (0.03) 1.58 (0.04) 1.49 (0.03) Kidney, pelvic, heart fat, % 2.03 (0.09) 2.06 (0.13) 2.08 (0.09) 2 b a,b a Ribeye area, cm 92.7 (1.42) 90.2 (1.88) 87.0 (1.40) a a,b b Yield grade 2.90 (0.09) 3.19 (0.12) 3.22 (0.09) Marbling score 5.44 (0.17) 5.55 (0.23) 5.83 (0.17) Quality grade 17.00 (0.21) 16.91 (0.27) 17.31 (0.20) a,b Values without common superscripts differ (P < 0.05). *Adjusted end weight = hot carcass weight/mean dressing percentage. Marbling score: 5 = small amount, 6 = modest amount. Quality score 16 = select, 17 = low choice, 18 = average choice. and Meyer et  al. (2005) who showed that early weaning, especially when it is accomplished in the weaned calves that had been exposed to concen- absence of other stressors such as co-mingling and trate feeding for longer periods of time had an ad- transport, is not as stressful as people perceive it vantage at harvest over steers weaned at an older to be based on animal behavior, particularly when age. This principle could also apply to the com- the cattle are being managed in a rotational grazing parison of normal-aged and delay weaned cattle. system where they receive human contact multiple Thompson et al. (2011) reported no difference be- times per week. tween A and N steers in REA, backfat thickness, or marbling score their study. Delayed weaned ACKNOWLEDGMENTS steers had poorer yield grade than A  (P  =  0.02) The author wishes to acknowledge Mark in the present study, due to their smaller REA; Clements and all the staff at Cherry Research however, based on current grid marketing stand- Farm (Goldsboro, NC) and at Butner Beef ards, no Yield Grade discounts across treatments Cattle Field Laboratory (Bahama, NC) for their would be expected. The steers received an average assistance with this project. Without their con- quality grade of Low Choice. tinued support and hard work, completion of this study would not have been possible. We are grateful for consistent funding from the North IMPLICATIONS Carolina Cattle Industry Assessment for the dur- Results of this study imply that when steers ation of the project. Lastly, we are also grateful are followed to harvest, weaning strategy has little to Dr Philipe Moriel (Range Cattle Research and impact on the efficiency of production or on end Education Center, University of Florida, Ona, product quality. The presence of nasal lesions in 12 FL) for his assistance with analysis of blood sam- of 38 steers which received nose flaps suggests fur - ples for hormones. ther research into the animal welfare implications Conflict of interest statement. None declared. of this strategy may be warranted. This study also suggests that the producer who sells his/her cattle LITERATURE CITED after a brief preconditioning period should con- Arthington,  J.D., R.F.  Cooke, T.D.  Maddock, D.B.  Araujo, sider the weaning strategy chosen. Our data indi- P.  Moriel, N.  Dilorenzo, and G.C.  Lamb. 2013. Effects cates that if cows are in good body condition and of vaccination on the acute-phase protein response and there is adequate pasture forage available, delaying measures of performance in growing beef calves. J. Anim. weaning would enhance ADG and allow the sale Sci. 91:1831–1837. doi:10.2527/jas.2012-5724. Arthington, J.D., S.D. Eichert, W.E. Kunkle, and F.G. Martin. of heavier calves, increasing profitability. Humoral 2003. Effect of transportation and commingling on the data collected in this trial were not consistent with acute-phase protein response, growth, and feed intake of data presented in the literature. Had our sample newly weaned beef calves. J. Anim. Sci. 81:1120–1125. doi: size been larger, we may have seen clearer humoral 10.2527/2003.8151120x. effects; however, since all the steers remained Arthington, J.D., J.W. Spears, and D.C. Miller. 2005. The effect within published reference ranges, it may be that of early weaning on feedlot performance and measures of Translate basic science to industry innovation Comparison of three weaning strategies stress in beef calves. J. Anim. Sci. 83:933–939. doi:10.252 Appl. Anim. Behav. Sci. 129:18–27. doi.org/10.1016/j. 7/2005.834933x. applanim.2010.10.003. Boland, H.T., G. Scaglia, W.S. Swecker, Jr, and N.C. Burke. Meyer,  D.L., M.S.  Kerley, E.L.  Walker, D.H.  Keisler, 2008. Effects of alternate weaning methods on be- V.L. Pierce, T.B. Schmidt, C.A. Stahl, M.L. Linville, and havior, blood metabolites, and performance of beef E.P. Berg. 2005. Growth rate, body composition, and meat calves. Prof. Anim. Sci. 24:539–551. doi:10.15232/ tenderness in early vs. traditionally weaned beef calves. J. S1080-7446(15)30903–7. Anim. Sci. 83:2752–2761. doi:10.2527/2005.83122752x. 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Influence of weaning strategy on behavior, humoral indicators of stress, growth, and carcass characteristics

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© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science.
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Influence of weaning strategy on behavior, humoral indicators of stress, growth, and carcass characteristics †,1 † † ‡ Sharon Freeman, Matt Poore, Carrie Pickworth, and Mark Alley † ‡ Department of Animal Science, North Carolina State University, Raleigh, NC, USA; and Technical Service Veterinarian, Zoetis, Inc., Cary, NC, USA ABSTRACT: Weaning is one of the most stressful d of age). The A  and D calves were more active events a calf experiences in our current beef pro- than N calves in the first 2 to 3 d after weaning duction system. Its effects may include reduced but settled down to similar activity levels to N by feed intake, increased activity, slower growth, and the day 4. The A and D groups were more vocal increased susceptibility to disease. This study was than N during the same time frame. Cortisol and designed to evaluate weaning after a 7-d place- haptoglobin remained within normal reference ment of nose flaps at 7 mo (N , n = 40) and delay- ranges. Average daily body weight gain (ADG) ing weaning by 49 d relative to 7-mo weaning (D, was greater for D than A, who in turn had greater n  =  39) as alternatives to the industry standard; ADG than N during the first 42 d after A and N abrupt weaning at 7 mo of age (A, n  =  39). The calves were weaned (0.69, 0.54, and 0.37 kg/d for 4-yr trial utilized Angus and Angus X Senepol D, A, and N, respectively; P  <  0.01). All treat- steer calves. Calves were randomly assigned to ment groups graded Low Choice at harvest and weaning strategy after being stratified by dam exhibited similar efficiency of gain during growth parity (heifer/cow), hair coat phenotype (normal/ and finishing (P > 0.2). Based on ADG during slick), and body weight. Behavioral observations the 42 d after weaning, we recommend delaying were made on five steers per strategy group per weaning when available pasture and cow body year over the weeks surrounding weaning. Activity condition support this strategy. When conditions levels were determined by accelerometers worn on do not permit delayed weaning, abrupt weaning neck collars. Blood samples were obtained from may be the next viable option based on animal the observed cattle during the last 2 yr to deter- welfare concerns and increased handling to place mine haptoglobin and cortisol concentration. and remove the flaps. Nose flaps reduced vocaliza- Once weaned, the steers were followed through tion at weaning but resulted in less postweaning finishing and carcass characteristics obtained at ADG. Based on our data, we suggest that abrupt harvest. Twelve of 38 steers in the N group had weaning under the conditions of this study, is less sores in their nostrils from the nose flaps when the stressful than we perceive it to be, based on calf flaps were removed at weaning of A/N (237  ± 3 behavior. Key words: activity, behavior, carcass characteristics, hormones, weaning strategy © The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science. This is an Open Access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Transl. Anim. Sci. 2021.5:1-16 doi: 10.1093/tas/txaa231 Corresponding author: sfreeman@ncsu.edu Received June 23, 2020. Accepted December 18, 2020. 1 Freeman et al. INTRODUCTION In current U.S.  beef production systems, weaning (the separation of a calf from its dam) is perhaps the most stressful experience a calf will face. According to USDA-NAHMS (2010), 49.8% of calves are removed from the presence of their dams abruptly and relocated away from their farms of origin. Rarely is this traumatic event an iso- lated source of stress, since weaning is also often used as a convenient time to vaccinate, deworm, dehorn, and/ or castrate. Because all these routine husbandry practices can be stressful, their combin- ation into a single event can have deleterious effects on calves’ wellbeing (Weary et al., 2008). The behavioral response to weaning in calves is multi-faceted. Feed intake is often reduced as a result of several factors, including more time spent walking/seeking, exposure to novel feeds, and changes in social structure in the herd (Veissier and Neindre, 1989; Price et al., 2003). Reduction in feed intake leads to weight loss or slower body weight gain (Price et al., 2003). Weaning may result in de- Figure 1. Nose flap before (a) and after (b) insertion into the nose pression and/or aggression (Veissier and Neindre, of a calf to prevent suckling. 1989). In addition to behavioral changes, stress at weaning has been shown to alter the concentrations were, therefore, to 1)  characterize calf behavior in of a variety of humoral compounds as the weaned the weeks surrounding weaning; 2)  assess calf ac- animal copes with the stressor (Arthington et  al., tivity levels with the use of accelerometers during 2005). Among these are cortisol and haptoglobin. the same time period; 3) monitor changes in hapto- The stress caused by weaning can increase the globin and cortisol levels during weaning; 4) quan- susceptibility of calves to disease, especially bo- tify growth efficiency during preconditioning; and vine respiratory disease (Yates, 1982), which is ex- 5)  document any impacts of weaning strategy on tremely costly to the beef industry in the United feedlot performance and carcass merit. States. According to USDA-NASS, about 2 million head of cattle are placed in feedlots each month MATERIALS AND METHODS (USDA-NASS, 2018). An estimated 16.2% of these are treated for respiratory disease after their arrival The 4-yr trial (2013–2016) was conducted at (USDA–APHIS, 2013) at a direct cost of $23.60 Cherry Research Farm (CRF; Goldsboro, NC) per head or about $91.7 million per year. This does and Butner Beef Cattle Field Laboratory (BBCFL; not account for production losses or mortality; Butner, NC) with approval from the Institutional however, it demonstrates the impact stress-related Animal Care and Use Committee at North Carolina disease has on the industry. State University (protocols #13-081-A, #13-124-A, Strategies purported to reduce stress at weaning, and #16–152). such as nose flaps designed to prevent suckling while allowing physical contact with the dam (Figure  1) Animal Husbandry Birth Through Preconditioning, and delaying weaning to more closely adhere to a Including Treatment Assignment natural weaning time, are available; however, there has been little research to quantify the impact of Calves were born in winter to early spring these strategies on animal behavior, humoral re- (December–March), castrated at birth, and reared sponse, and performance beyond the precondi- on pasture at CRF at their dams’ side for an average tioning phase, including impacts on carcass merit. of 237  ± 3 d.  They received minimal concentrate Hypothesizing these strategies could result in meas- prior to weaning and had free-choice access to a urable reductions in stress-related behaviors and complete mineral supplement (supplied 16% Ca, increases in performance, the goals of this study 1.9% P, 11.4% Mg, 0.1% K, 1,002 ppm Cu, 35 ppm Translate basic science to industry innovation Comparison of three weaning strategies Se, and 113,500 USP IU vitamin A; Renaissance per treatment) received accelerometers (Actical®, Nutrition, Inc., Roaring Springs, PA) and water. Philips Respironics, Bend, OR), attached via neck Steer body weight (BW) was recorded and steers collars, as they passed through the handling facility. were vaccinated according to normal farm protocol The OBS steers were sorted out of the main herd (2  mL/steer SC, Vision 7 Somnus with SPUR®, and put in a 3.4 ha pasture with their dams, sep- Merck Animal Health, Omaha, NE; 5  mL/head arated from the remainder of the herd to facilitate SC, Bovi-Shield Gold®, Zoetis, Inc., Parsippany, observation. The D steers, including D OBS, and NJ) and dewormed (5 mg/kg body weight fendben- their dams were maintained with the main herd dazole, Safeguard, Merck animal Health, Omaha, until 7 d prior to their weaning day. Forage in both NE) 28 d prior to weaning (see Figure 2 for a time pastures was similar and consisted primarily of line of the trial). Thirty steers per year in years-1 to bermudagrass (Cynodon dactilon (L.) Pers.), crab- -3 and 28 steers in year-4 were selected and strat- grass (Digitaria siderograpta Chiov.), and dallis- ified by hair coat phenotype (assessed at birth to grass (Paspalum dilatatum Poir.). Mixed grass hay be slick or normal), dam parity (first calf heifer or or small grain baleage was offered to both animal cow), and BW (mean  =  254  ± 6.7  kg). They were groups when pasture became limiting. randomly assigned to one of three weaning strategy After 7 d, both OBS and non-OBS steers from groups. Strategies were traditional, abrupt weaning all three treatment groups had BW recorded (A (A, n = 39); weaning after placement of a nose flap and N 7 d preweaning), nose flaps were placed in for 7 d (N, n  =  40); or weaning delayed by 49 d N steers (both OBS and non-OBS), and steers and from the date A  and N were weaned (D, n  =  39). dams were returned to their respective pastures. Treatments A and N ran concurrently. At the end of another 7 d, all steers (OBS and The steers and their dams were maintained as a non-OBS, all treatments) had BW recorded, nose single herd until 14 d prior to weaning. At this time, flaps were removed from N, and A  and N calves because there were only 10 accelerometers available were placed into corrals (A/N OBS steers, alone, in and to create greater uniformity among the steers a small corral [14.6  × 17.7 m] and A/N non-OBS used to determine activity levels and behavior, the steers in a large corral [18.9 × 67.1 m] with weaned heaviest five calves from mature cows in each treat- heifers). Weaning was delayed by 8 d for A and N ment group, balanced for hair coat phenotype, in yr 4 as the result of flooding from Hurricane were selected for behavior observation (OBS) and Matthew. Some non-OBS N steers lost their nose activity level determination. Using similarly sized flaps prematurely each year (2, 1, 2, and 7 for steers also protected the smaller steers from poten- 2013, 2014, 2015, and 2016; respectively). All OBS tial, postweaning aggression by larger steers while steers kept their nose flaps for the duration of the they would be housed, postweaning, in a corral. observation period. All three groups of steers had BW recorded 14 d Weaned calves had ad libitum access to hay, before weaning of A  and N.  This was considered water, and trace mineralized salt. Grain (80.2% the actual start of the experiment and the day ground corn, 17.3% soybean meal, and 2.5% when steers designated for A  and N OBS (n  =  5 limestone; as fed) was offered each morning at Figure 2. Time line of the experiment for each year. Translate basic science to industry innovation Freeman et al. approximately 0750  h, increasing from 1.4 to disturbance to the cattle and to reduce variation 2.3  kg per head per day over the 3 d immediately created by multiple observers. Observations were after weaning. Grain offered was held at 2.3 kg per made on four consecutive days (Tuesday through animal throughout the remainder of the precondi- Friday). The observer watched for predesignated tioning period. Weaned, OBS steers remained in the behaviors that were considered key indicators of smaller corral for 7 d, after which the accelerom- stress or absence thereof. Categories were grazing, eters were removed and they were then turned in eating hay, standing still or walking slowly, suckling with the larger group of weaned cattle. All weaned or attempting to suckle, ruminating, lying down, cattle had BW recorded 7 d after weaning. and other behaviors (included drinking, groom- Dams of the A and N cattle were sent to a pas- ing, eating minerals, scratching, playing, aggres- ture out of sight of their offspring to accomplish sion, etc.). Individual vocalizations were counted. weaning of A and N treatment groups. The D steers Observations of each individual steer were made at and their dams were placed in a separate pasture least three times during each 10-min interval and an to await delayed weaning. Dam body condition for effort was made to make the observations without all three treatment groups was assessed on a scale disturbing the animals. of 1–9 (1 being emaciated and 9, obese) at weaning The second observation period for A  and N of A and N in 2013–2015. Flooding prevented safe began 6 d before weaning, and was as described assessment in 2016. previously, lasting 4 d. During this period, A steers At 42 d after the weaning of A and N groups, had accelerometers, only, and N steers had both ac- steers in all three treatment groups had BW recorded, celerometers and nose flaps, allowing us to watch D OBS received accelerometers (7 d preweaning), for behavior changes in both groups caused by the and were returned to pasture for preweaning obser- placement of the nose flaps relative to base week. vation. All 10 D steers (OBS and non-OBS) were This period was not present during the observation housed together to facilitate care, both on pasture, of D, since no animals wore nose flaps. before weaning, and in the smaller corral, after The final observation period for all treatment weaning. The delay period between weaning of groups began the day after weaning day. It also pro- A and N and weaning of D remained consistent to ceeded as described earlier with the exception that protocol (49 d) in 2016. Delayed weaning and re- new behavior categories were tracked. Categories cording of weaning BW for D took place 7 d after after weaning included eating hay, eating concen- the placement of the collars (49 d after weaning of trate, standing still or walking slowly, pacing, lying A  and N) and final BW for D steers in this phase down, rumination, and all other behaviors. Again, of the experiment were collected 7 d after weaning, individual vocalizations were counted. Concentrate when accelerometers were removed. was offered after 20  min of observation had been Following the weaning of D steers, the weaned completed (at approximately 0750 h). Observations cattle were preconditioned for 45  ± 7 d at CRF were made for four consecutive days as previously prior to being shipped to BBCFL for growing described. and finishing. During the preconditioning period, After all observations had been completed, calves were housed on pasture, received 2.3 kg grain individual steer behavioral observations were tal- mix (80.2% ground corn, 17.3% soybean meal, and lied by category within 10-min periods and then 2.5% limestone; as fed) per head per day and had totaled for each day of observation by animal. access to ad libitum hay, trace mineralized salt, and The total number of observations was calculated water. for each steer by totaling all observed behaviors for each day. Rumination was considered a simul- taneous behavior and not tallied in the total. (e.g., Accelerometry and Behavior Observations A calf noted as standing or lying could also be ru- Behavioral observations began the day after ap- minating. Only the standing or lying was tallied in plication of the accelerometers (13 d before weaning the hourly total). The “other behaviors” category for A and N, 6 d before weaning for D). The obser- was also not included in the tally because many vations made during the first observation period were very short duration and were for observation served as a baseline week since none of the steers purposes, only. Percentage of total observations were subjected to treatment. Observations were for individual categories, including rumination, collected over 10-min intervals for 1 h, three times was then calculated (e.g., Observations tallied per day at approximately 0730, 1130, and 1530  h. as “standing” in day/total observations in day × A  single person made observations to minimize 100 = % standing). Translate basic science to industry innovation Comparison of three weaning strategies Accelerometers were preprogrammed to begin (2016). Intra- and inter-assay CV for haptoglobin measuring activity at 0800 h on the day they were (respectively) were 2.17 and 3.43% in year 3 and placed on the steers (at least 1 h prior to the place- 3.18 and 4.38% in year 4. Cortisol was determined ment of the first collar in its host animal). The ac- as a single assay with intra-assay CV of 5.30 and celerometers were programmed to collect data once 4.98% in years 3 and 4, respectively. per minute (the longest interval available) to ensure battery life throughout the collection period. None Husbandry at the Growing/Finishing Facility of the collars/accelerometers became displaced prior to the end of the data collection period. Steer BW was recorded upon arrival at BBCFL. Once removed from the calves 7 d after weaning, Steers were quarantined on pasture for 28 d and accelerometry data were downloaded using asso- adapted to a corn silage-based, growing total mixed ciated software (Actical 3.10; Respironics, Inc., ration (TMR, see Table  1 for ingredient compos- Murrysville, PA). One device malfunctioned in ition and Table  2 for nutrient content). Following year-2 and its data was not included in the analysis. quarantine, steer BW was again recorded and the Animal activity output was expressed as “relative steers stratified by hair coat phenotype, weaning activity units” (RAU). Relative activity data was to- treatment, and BW for assignment to 3 pens (2.7 × taled for each day of observation. 9.4 m). Pens were equipped with Calan gate feeders (American Calan, Northwood, NH) which allowed only one steer access and so permitted determin- Blood Collection for Humoral Analysis ation of individual feed intake. Steers received the Addition of new faculty between years 2 and growing TMR ad libitum and had access to free- 3 facilitated the analysis of blood for cortisol and choice water. Daily feed was weighed into each haptoglobin. As a result, during year-3 and -4, steer’s feeder in the morning and residual feed blood samples were collected via jugular venipunc- assessed visually at the next morning’s feeding. ture using 3.8  cm × 18-gauge needles into 10  mL Feed offered was adjusted up or down to achieve Vacutainer® tubes (Beckton Dickinson, Franklin maximum residuals of approximately 5% of feed Lakes, NJ) containing Lithium Heparin. Two tubes offered. Residual feed was removed and weight per steer were collected on day –14, –7, –5, 0, +2, recorded at 2-week intervals unless excessive re- and +7 relative to weaning for A and N and at day sidual was present, risking spoilage and contamin- –7, 0, +2, and +7 for D.  Blood tubes were imme- ation of the fresh feed. In this case, residual was diately placed on ice and stored until processing. removed more frequently and feed offered adjusted Plasma was separated by centrifugation at 2.316 × g downward. for 30 min. Plasma was pipetted into plastic storage Once the steers had learned how to operate the vials, frozen, and stored at –10°C. Once all samples gates, steer BW was recorded on two consecutive for the year had been collected, they were shipped days to obtain start weight for the growing phase. on dry ice to the University of Florida, Range Steer BW was recorded every 28 d until day 84, Cattle Research and Education Center, Ona, for when 2-d consecutive BW was recorded in prep- determination of plasma cortisol and haptoglobin aration for the transition to the finishing phase. according to procedures described in Moriel et al. To accomplish transition without digestive upset, Table 1. Diet composition of feedlot total mixed rations (TMR) with standard deviations (SD) fed to steers weaned at 237 d age either abruptly or after 7 d nose flap placement or after a 49 d delay at 286 d or age Component, % of DM (unless otherwise indicated) Growing TMR Finishing TMR Basal concentrate mixtures Corn 34.2 81.2 Soybean meal 60.4 13.0 Limestone 3.6 1.6 TM salt 1.3 0.3 Rumensin 90, kg/tonne 0.5 0.2 Vitamin A, D, E; kg/tonne 1.4 0.4 Total mixed rations (SD) Corn silage, % as fed 86.6 (3.47) 13.4 (0.32) Basal concentrate, % as fed 33.5 (3.47) 66.5 (0.32) Translate basic science to industry innovation Freeman et al. Table 2. Nutrient composition of feedlot total mixed rations (TMR) with standard deviations (SD) fed to steers weaned at 237 d age either abruptly or after 7 d nose flap placement or after a 49 d delay at 286 d or age Component, % of DM (unless otherwise indicated) Growing TMR (SD) Finishing TMR (SD) Dry matter, % 39.4 (4.17) 71.2 (3.19) Crude protein 12.5 (2.48) 12.5 (1.19) ADF 19.3 (3.01) 8.1 (0.68) NDF 31.4 (4.09) 16.5 (1.46) Ash 4.7 (1.25) 3.4 (0.95) Ca 0.5 (0.16) 0.3 (0.05) P 0.3 (0.05) 0.3 (0.01) Mg 0.2 (0.04) 0.2 (0.01) K 1.1 (0.22) 0.7 (0.03) Na 0.1 (0.08) 0.1 (0.05) Fe (ppm) 259 (76.7) 178 (35.7) Mn (ppm) 52 (5.8) 29 (4.2) Zn (ppm) 66 (24.3) 53 (24.3) Cu (ppm) 26 (11.4) 16.7 (3.2) TDN 74.6 (2.44) 82.8 (1.12) NE lact 0.78 (0.03) 0.87 (0.01) TMR was shifted over 10 d to the finishing for - made. Marbling scores were assigned and final mulation (Tables  1 and 2), after which the cattle yield grades (YG) calculated [YG  =  PYG + (re- received the finishing diet ad libitum until the ma- quired REA – actual REA) * 0.3  + (%  KPH – jority of the group had deposited at least 1.25 cm 3.5) * 0.2]. of backfat. Steer BW was recorded on day 140 and day 141 and as they were loaded for shipping to Cargill Meat Solutions (Wyalusing, PA) for har- Statistical Analysis vest 8.5 ± 6.8 d later. Shipping weights were used Design for this experiment was a randomized, to determine dressing percentage and adjusted end complete block replicated over 4 yr. Data were weights. analyzed using Proc Mixed of SAS (SAS v.  9.4; Samples of TMR and feed ingredients were SAS, Inc.; Cary, NC). For all models, year was the collected twice each week and stored at –10°C random term and where appropriate, calf was used until after the cattle had been harvested. Samples as a repeated measure. Class variables included year, of feed refusals were taken each time refusals were dam parity, hair coat phenotype, whether the steer removed from feeders. They were also stored at was OBS or not, status of the nose flap at removal –10°C. All samples were composited into monthly (missing or present), OBS period, day of OBS, and samples and dry matter (DM) content determined treatment group. Steers from N whose flaps were (Shreve et  al., 2006; NFTA method 2.2.2.5). lost prior to weaning were not included in the ana- Daily feed dry matter intake (DDMI) was calcu- lysis. One OBS steer lost its flap prior to scheduled lated from total feed DM offered and total refusal removal date; however, not during observation, so DM removed: (Feed DM offered–Refused DM)/ his data was included. Two calves had inexplicably number of days. high (10 times higher than average) haptoglobin levels at one collection day each (one at weaning in Carcass Measurements year 3 and the other 2 d after weaning in year 4). Hot carcass weights were recorded at har- These data points fell outside the 99th percentile as vest and dressing percentage calculated. Trained determined by Proc Univariate of SAS, so they were graders from USDA assigned quality and pre- not included in the analysis. Any main effect which liminary yield grades to the carcasses based on returned a P-value greater than 0.2 was eliminated visual appraisal. After carcasses had chilled for from the model as was interactions that returned P at least 24  h, measurements of back fat (FAT); > 0.2. Final models included treatment, hair coat kidney, pelvic, and heart fat (KPH); and rib eye phenotype, OBS period, day of OBS, and the inter- area (REA, between the 12th and 13th rib) were action of period and day, where it was significant. Translate basic science to industry innovation Comparison of three weaning strategies Significance was defined as P ≤ 0.05 and a trend was small and would not have impacted the outcome of defined as 0.05 < P ≤ 0.10. While hair coat pheno- the trial. type did return significant differences for some Body weight among treatment groups did parameters, there were no significant interactions not differ at the trial’s initiation (Table  3) and between hair coat phenotype and weaning strategy. the treatment groups remained similar in BW Differences for hair coat phenotype will not be dis- through preconditioning and at shipment to the cussed in this paper. finishing facility. We also found few differences in ADG by the steers. We had hypothesized that N calves, deprived of suckling, would gain less RESULTS AND DISCUSSION BW than A  calves that had accessed to milk as a supplement to pasture and hay. Boland et  al. Birth Through Preconditioning (2008) and Enríquez et al. (2010) reported signifi- Cow body condition.  Cow body condition cantly greater ADG by control calves, destined scores at the weaning of A  and N were 5.5, 5.4, for abrupt weaning, than by calves wearing nose and 5.9 (SEM = 0.16) for 2013, 2014, and 2015; flaps in the period prior to weaning. Haley et  al. respectively, well within the 5.0–7.0 range recom- (2005) reported greater gain in control calves than mended for breeding beef cattle (Eversole et al., calves wearing nose flaps in one trial, but not in 2005). Adequate condition at this stage indicated another, similar to our findings. There was no de- that no harm would come to the cows by allowing layed weaning treatment group in any of these steers in the D group to continue to suckle be- trials. There is no clear explanation for variation yond the traditional weaning date used for A and in the ADG results in these experiments. It is pos- N.  Cows who reared A  calves had lower BCS sible that day-to-day variation in BW negated than cows who reared N calves (5.4 and 5.8, re- small treatment differences. Possible contributing spectively; SEM = 0.11, P = 0.01) and cows who factors to the differences in results between experi- reared D calves were intermediary (BCS  =  5.6). ments are management differences such as penning There is no clear explanation for these find- cattle as compared to leaving them on pasture or ings. Since all the cows remained within the re- moving them from one location to another at the commended range and differences were small, onset of the trial. however, the differences are not likely of any bio- During the 7 d following weaning of the A and logical significance. N groups, the D steers gained more than their Steer growth.  Steers were 209  ± 3 d of age at weaned peers (Table  3, P  <  0.01) while A  and N treatment assignment and did not differ by treat- gained at similar rates. This is not surprising since ment (P  =  0.72). Observed calves were older than the D steers were able to supplement forage with those not observed (212 vs. 206 d, P < 0.01). Since milk and they remained with their dams. Boland the heaviest calves were selected for observation, et  al. (2008) and Enríquez et  al. (2010) reported it is logical that they were also the older animals. greater ADG for abruptly weaned cattle as com- The difference, while statistically significant, was pared to those that had worn nose flaps. Haley et al. Table 3. Growth parameters among steer calves weaned abruptly (A, 237 d age), after 7 d nose flap (N, 237 d age) application, or after a time delay of 49 d (D, 286 d age) from birth until shipment to a finishing fa- cility with standard errors (SEM) Parameter A N D SEM BW* 14 d before weaning A and N, kg 260.4 263.8 263.2 5.5 BW 7 d before weaning A and N, kg 266.6 268.4 262.7 5.3 BW at weaning A and N, kg 275.7 278.1 273.3 4.7 BW 7 d after weaning A and N, kg 280.1 279.8 286.4 5.0 BW 42 d after weaning A and N, kg 302.5 285.2 293.1 4.8 BW at shipment to finishing facility, kg 321.4 317.3 314.1 4.8 ADG*: birth to weaning of A and N, kg/d 1.01 1.02 1.00 0.02 ADG: 7 d preweaning of A and N, kg/d 1.33 1.13 1.71 0.59 a a b ADG: 7 d postweaning of A and N, kg/d 0.61 0.31 1.86 0.26 b a c ADG: 42 d after weaning A and N, kg/d 0.54 0.37 0.69 0.04 a,b,c Values without common superscripts differ (P ≤ 0.05). * BW: body weight; ADG: average daily gain. Translate basic science to industry innovation Freeman et al. (2005) reported inconsistent results after weaning for cattle reported in the literature are variable but and suggested plain of nutrition being better in 1 yr fall within the range of 0.3 μg/dL (Hopster et  al., than the others which could have caused the differ- 1999) to 5.5 μg/dL (Doornenbal et  al., 1988). All ence in results. cortisol concentrations in the present study were At 42 d after weaning A and N, BW of all three within the normal range (Table 4). Mean cortisol in treatment groups remained similar; however, ADG D was greater (P < 0.01) than in A and N steers and varied (Table  3, P  <  0.01). The D group gained was greatest when baseline concentration was de- faster than A, which gained faster than N.  Haley termined, prior to weaning and observation. There et al. (2005) reported that in the period of 7–21 d is no clear explanation why this treatment group postweaning, calves that had worn nose flaps and would have elevated cortisol as compared to their abruptly weaned cattle gained similarly. Enríquez A and N peers. Doornenbal et al. (1988) reported et  al. (2010) reported similar gains for abruptly that serum cortisol increased from 3.85 to 5.49 μg/ weaned and calves that had worn nose flaps over dL as steers aged from 7.5 to 12.5 mo; however, there the 44-d postweaning period. Management differ- was only a 7-week age difference between the D and ences could possibly explain the difference between A/N calves so age difference may only account for a our results and those reported elsewhere. The small portion of our observed treatment variation. calves in both other trials mentioned were pastured Cortisol remained consistent within D steers over and received no supplementation while the weaned time; however, the A and N steers had variations in calves in our trial were housed in a drylot where cortisol over the course of the experiment. Cortisol they received hay and concentrate. While our calves was elevated in A at nose flap insertion and in both had been exposed to the hay previously, they had A and N 2 d after nose flap insertion as compared not been completely reliant on it and their experi- to baseline levels. Since the response was seen in ence with supplemental concentrate was minimal. both groups and concentrations were back to base- Additionally, 12 of 38 steers that had worn nose line levels at weaning, increased handling or the flaps had bloody sores inside their nostrils. It is pos- presence of the observer may have had an influence sible that soreness reduced feed intake. Incidence on cortisol in these calves, which as the trial pro- of nasal sores from the use of nose flaps has not gressed, had time to adapt to both handling and the been described in the literature so its frequency is observer. The D calves were handled at the same unknown. times as the A/N calves which could explain their Humoral indicators of stress.  Plasma cortisol lack of response over the baseline week. and haptoglobin are low in healthy, unstressed Haptoglobin is often undetectable in healthy cattle. Baseline cortisol reference concentrations cattle; however, research indicates reference Table 4. Concentrations of humoral stress indicators in steers weaned abruptly (A, 237 d age), after 7-d placement of a nose flap prior to weaning (N, 237 d age), or after a delay of 49 d (D, 286 d age) with standard errors (SEM) Humoral factor A N D SEM a a b Cortisol, μg/dL 1.90 1.58 2.37 0.14 a;x ab;xy b Baseline 1.70 2.07 2.70 0.28 yz yz Nose clip insertion 2.43 2.25 n/a 0.21 z z Nose clip + 2 d 2.56 2.41 n/a 0.21 xy xy Weaning day 1.84 1.54 1.93 0.28 ab;xyz a;x b Weaning + 2 d 1.90 1.30 2.43 0.28 ab;xyz a;x b Weaning + 7 d 2.17 1.43 2.44 0.28 b b a Haptoglobin, mg/dL 4.26 5.59 0.29 0.88 b;z b;z a;y Baseline 8.73 9.21 3.57 1.73 z y,z Nose clip insertion 7.89 7.53 n/a 1.73 y,z y,z Noseclip + 2 d 5.32 6.61 n/a 1.73 x,y x x,y Weaning day 1.80 1.21 ND* 1.83 b;x,y b;y,z a;x Weaning + 2 d 4.88 7.04 ND 1.83 a,x b;x,y a;x,y Weaning + 7 d 1.61 4.81 0.92 1.73 a,b Values without common superscripts differ between treatments within time (P < 0.05). x,y,z Values without common superscripts differ between times within treatments (P < 0.05). *ND: not detectable. Translate basic science to industry innovation Comparison of three weaning strategies concentrations of 0–20  mg/dL (Gånheim et  al., more consistent over the course of the experiment. 2003; Chan et al., 2004; Seppä-Lassila et al., 2013) Because we saw no consistent patterns of change for for healthy cattle. Haptoglobin has been shown to cortisol and haptoglobin and because of our small increase above baseline with the challenge of re- sample size, it is difficult to determine whether there spiratory disease (Godson et  al., 1996) with con- was a humoral stress response or not. centrations peaking (110 mg/dL) 8 d after infection. Steer relative activity and behavior.  The ac- At weaning, Arthington et al. (2003 and 2005) re- celerometer output is reported as RAU, which ported peak concentrations (2.4–14.9  mg/dL) 3–4 are an omnidirectional reflection the subject’s ac- d after weaning. While within the reference range tivity and energy expenditure. Robért et al. (2009) found within the literature, they considered the demonstrated accelerometers can successfully be increase they observed a response to the stress of used to accurately detect such activities as lying, weaning. Haptoglobin concentrations in our steers standing, and walking and that they are useful in remained within the reference range throughout monitoring circadian activity patterns of feedlot the trial (Table 4). For all treatment groups, hapto- steers (Robért et  al., 2011). Treatment and treat- globin concentrations tended to decline between ment by period and treatment by period by day baseline sampling and weaning. Only those in N interactions were detected (P  <  0.01). Calves as- had elevated haptoglobin at 2 d after weaning as signed to the D group had fewer RAU during the compared to concentrations on weaning day; how- week for determining baseline activity levels than ever, this may not have been the optimum time to calves assigned to either the A  or N treatments detect changes in this protein and it is possible (10,545 vs. 21,969 and 22,172 RAU, respectively; that had we been able to sample in the 3–4 d after P  <  0.01). The most obvious explanation for the weaning time period, elevations would have been difference is that by the time the accelerometers detected. were placed on the D calves (42 d after A  and Across all sampling times, the steers in the N were weaned), pasture was scarce and so they A  and N treatment groups had greater average spent more time at a hay feeder, where they were haptoglobin concentrations than D. The difference relatively still, than did the A and N calves, which was driven largely by the greater concentrations spent more time grazing and only relied on hay found in A and N at baseline and preweaning sam- when pasture diminished. This assumption is sup- ples since levels were similar among treatments at ported by a decline in RAU for the A and N calves weaning. One possible explanation is the greater over the course of observation periods 1 (Figure 3, time interval from preweaning vaccinations for baseline) and 2 (nose flaps placed). Day to day the D steers (70 d) as compared to A  and N (14 variation was likely influenced by weather. All the d); however, Arthington et al. (2013) and Rodrigues cattle were stationary during windy periods of et  al. (2015) found haptoglobin levels returned to heavy precipitation and such weather existed more prevaccination levels 3–6 d after vaccination. Based in some years than others and could have resulted on these findings, haptoglobin in our A  and N in less RAU for certain days. calves should have been at normal levels before the The greatest difference in activity levels were trial began. There is therefore no clear explanation seen over the first 4 d after weaning. Both the for the difference and the concentrations reported A  and D calves had significantly more RAU than for A and N were still within the range for healthy N (Figure  3, P = 0.03) on day 2. On day 3 and 4, cattle. Having a larger number of cattle could have D calves continued to have more RAU than N possibly given us additional insight. (P  =  0.02 and 0.06 for day 3 and 4, respectively) Haptoglobin levels responded to time within while A calves were intermediary in RAU and did each treatment (Table  4). For A  and N, levels de- not differ from either D or N (P > 0.15). By the clined from collection of baseline samples to fourth observation day after weaning, all treatment weaning, rose slightly by 2 d after weaning, and groups exhibited similar RAU. Weaned calves were then declined again to preweaning levels by 7 d housed in a corral and so had limited space for postweaning. Thompson et al. (2011) reported ele- movement. Had they been weaned in a pasture set- vated haptoglobin 10 d after weaning in calves that ting, RAU counts and treatment differences might had worn nose flaps for 7 d and in control calves as have been even greater; however, they probably well. This time frame was beyond that in our study would have followed a similar pattern over time. and beyond what was described in other research, Price et  al. (2003) reported calves weaned on pas- previously mentioned. Delay weaned steers’ hapto- ture increased their walking by 2.5 times over calves globin was undetectable by weaning and remained weaned to a drylot. Translate basic science to industry innovation Freeman et al. Figure 3. Relative activity of steers weaned abruptly (237 d age), after 7-d placement of a nose flap prior to weaning (237 d age), or after a delay of 49 d (286 d age). We are not aware of other published research N during the baseline week since calves were of where 3-dimensional accelerometers were used to similar age and all had similar access to suckling. record activity levels specifically associated with This pattern continued during the week of nose weaning; however, Haley et  al. (2005) placed flap placement, with A  suckling more frequently pedometers, which measure 2-dimensionally, on than N attempted to suckle (7.2 vs. 4.7%, respect- a subset of their experimental cattle and noted ively; P  <  0.01). Over this observation period, that the number of steps per day did not differ both groups suckled or attempted to suckle more between control and nose flap calves during the frequently than during the baseline week. The ob- baseline period. Once nose flaps were placed, the server reported several A  calves nursing from N nose flap cattle took about 2,000 more steps per dams during the nose flap period when N calves day than the control group. They reported on could not access milk and N calves persistently the day following weaning, the abruptly weaned trying to suckle. The increase in suckling and/or at- calves took over 17,500 steps more than the tempting to suckle by A calves could have been due calves that had been fitted with nose flaps. Both to the opportunity to obtain milk from multiple treatment groups returned to baseline levels of dams but this cannot be affirmed based on study steps per day by day 4 after weaning. Over the design. Suckling attempts by N calves tended to de- 8-d period surrounding weaning, their nose flap cline over the 4-d observation to 2.5% of observa- calves averaged 4,084 fewer steps than the con- tions (day 1 vs. day 4, P = 0.07). This is similar in trols. These results show similar activity patterns time frame to data reported in Hötzel et al. (2012) to those in our study. who saw suckling attempts decline 4–5  days after The objective of placing nose flaps is to prevent nose flap placement. suckling while allowing physical contact with the Walking or pacing the fenceline is a commonly dam. During the baseline period, A calves were ob- observed behavior in calves recently separated from served suckling and/or attempting to suckle more their dams. The calves in the present study exhib- than either N or D calves (Table 5, P < 0.01). Since ited this seeking behavior although it declined in older calves (D) would be expected to be closer to A and D over the course of the observation period natural weaning, the difference between A and D is (Table  5, P  =  0.07). On the first observation day, not surprising; however, there seems to be no ob- the A  steers paced more than the N steers and vious explanation for the difference between A and the D steers were intermediary, in agreement with Translate basic science to industry innovation Comparison of three weaning strategies Table 5. Behavior of steers weaned abruptly (A, 237 d age), after placement of a nose flap for 7 d (N, 237 d age), or after a 49-d delay (D, 286 d age) presented by treatment least square mean (LSM) or daily observa- tions with standard errors (SEM) Treatment Behavior (units) Observation period LSM or day no. A N D SEM b,x a,x a Suckling or attempt (% of observations) Baseline week LSM 4.8 2.8 2.3 0.7 b,y a,y Nose flap in LSM 7.4 4.7 N/A 0.7 b,y a,y Noseflap day 1 9.0 6.0 N/A 1.4 x xy Noseflap day 2 4.6 5.4 N/A xy xy Noseflap day 3 6.7 4.9 N/A b,y a,x Noseflap day 4 9.2 2.5 N/A Pacing (% of observations) Postweaning LSM 6.6 3.2 4.1 1.6 b,z a ab,y Postweaning day 1 18.8 2.8 11.7 3.5 y xy Postweaning day 2 7.2 2.1 4.2 x x Postweaning day 3 0 5.4 0.8 x x Postweaning day 4 1.1 2.4 0 x x x Vocalizations (count per hour) Baseline week LSM 3.3 2.0 1.0 1.5 x x Nose flap in LSM 2.9 3.5 N/A 1.3 c,y a,y b,y Postweaning LSM 20.6 7.3 14.4 1.5 c,y a,y b,y Postweaning day 1 46.5 12.8 39.3 3.0 c,y a,x b,y Postweaning day 2 26.8 6.8 13.9 x x x Postweaning day 3 6.1 5.5 3.4 x x x Postweaning day 4 3.1 4.1 0.9 y y y Eating forage (% of observations) Baseline week LSM 45.0 45.0 46.3 2.1 y y Nose flap in LSM 44.0 46.0 N/A 2.1 a,x b,x b,x Postweaning LSM 13.1 22.3 25.9 2.1 a,x b b Postweaning day 1 8.7 23.8 31.4 4.1 Postweaning day 2 12.8 21.1 23.2 Postweaning day 3 20.1 25.5 28.7 Postweaning day 4 10.9 18.6 20.1 b,x b,xy a Lying down (% of observations) Baseline week LSM 22.6 21.8 14.3 2.2 x,y x Nose flap in LSM 25.2 20.6 N/A 2.2 b,y b,y a Postweaning LSM 30.9 30.1 14.9 2.2 a,b Values without common superscripts differ between treatments within period (P < 0.05). x,y,z Values without common superscripts differ between periods or days within treatment (P < 0.05). pedometer measurements by Haley et  al. (2005). to weaning (Table  5, P  =  0.02). Nose flaps re- Pacing declined for A  and D over the first 2  days duced vocalizations compared to both A  and D after weaning. On day 3 after weaning, pacing ac- (P  <  0.01). All the calves had returned to pre- tivity was similar across treatments (P = 0.17). The weaning levels of vocalization by the third day observed pacing helps explain the pattern of the of observation, with N calves achieving prewean- RAU. We detected no overall treatment differences ing levels a day earlier than A  or D, suggesting for pacing behavior. they may have dealt with weaning anxiety more Vocalization in cattle is also often associated quickly. Haley et  al. (2005) also reported greater with seeking behavior when herd members are sep- vocalization counts on the second and third days arated from one another and with stressors, such after weaning from abruptly weaned calves as as hunger (Weary et al., 2008). Prior to weaning, compared to calves weaned following placement vocalization counts were similar among treatment of a nose flap. Vocalization counts for the control groups and low (Table 5; P > 0.15). Vocalizations calves were similar in magnitude to those in our were attributed, by the observer, to movement of study. Price et  al. (2003) used fenceline weaning feed or animals within sight of preweaning pas- instead of placing nose flaps. With this alternate, tures. Following weaning, vocalization counts in- 2-step weaning process, vocalizations were also creased dramatically. All three treatment groups reduced as compared to abrupt weaning. Again, had greater vocalization counts on the first day counts per animal per hour were similar in magni- of observation after weaning than they had prior tude to those in this study. Translate basic science to industry innovation Freeman et al. Cattle in the A and N treatment groups spent accepted it (P > 0.36). Time spent eating concen- more time grazing during the baseline week than trate was determined by pecking order within each those in D (33, 27, and 2% of observations, re- group rather than by treatment. Concentrate was spectively; P  <  0.01). As mentioned earlier, this cleaned up within 30 min. is likely due to changes in pasture forage avail- Calves from all three-treatment groups spent ability than to applied treatments. Conversely, D similar amounts of time lying down prior to cattle spent more time eating hay during the base- weaning (Table  5, P > 0.61). During the observa- line week than A  or N (44, 12, and 18% of ob- tion period after weaning, the D calves spent less servations, respectively; P  <  0.01). When grazing time lying down than either A or N calves, with the and hay observations were combined into “eating exception of the fourth day after weaning, when forage,” treatment differences before weaning dis- all spent similar amounts of time lying down. We appeared and all the cattle spent about 45% of had anticipated that A calves would spend less time their time eating forage (Table  5). This is similar lying down than N calves, after weaning, and that in magnitude to behavior reported by Price et al. D and N calves would follow similar patterns for (2003) prior to weaning. lying down. One possible explanation for what we Following weaning, the calves’ only forage observed is that the N calves, who paced less than source was hay. All treatment groups spent less A and seemed more at ease in the absence of their time eating forage postweaning than prewean- dams, may have been prone to lying down and that ing (Table  5; 18% vs. 45%, respectively; P  <  0.01). their behavior influenced their A  peers, since all Calves in the A  group tended to spend less time were housed together. These two treatment groups eating forage than either N or D (13% vs. 22 and ran concurrently and had been housed together to 26%, respectively; P = 0.06); however, the majority facilitate observation by a single observer from the of this difference was the result of the earliest part initiation of the trial and so they remained together of the observation period, since by the third day after weaning. Delayed wean calves were housed in of observation after weaning, there were no signifi- absence of other weaning strategy groups. Haley cant differences (Table  5). Haley et al. (2005) also et  al. (2005) reported that abruptly weaned calves reported less time spent eating among abruptly spent less time lying down than those weaned with weaned calves as compared to calves weaned after nose flaps, in contrast to our observations. Their nose flap placement. Boland et al. (2008) reported cattle were maintained on pasture rather than being that calves with nose flaps in place spent less time housed in a corral and this difference may have in- eating (grazing) than either control or calves sep- fluenced behavior. arated from their dams by a fenceline prior to re- We postulated that another possible influence mote separation from the dams. Following remote on lying down could have been environmental tem- separation of the dams, Boland et  al. (2008) re- perature. The Thermal Heat Index (THI) devel- ported that there was no further reduction in eating oped by Thom in 1959 is the basis for the Livestock time among calves that had worn nose flaps, while Weather Safety Index (WSI; LCI, 1970) which div- abruptly weaned controls and fenceline calves ex- ides heat stress risks into classes. Based on the WSI, perienced reductions in eating to levels below those THI between 23 and 26°C can reduce productivity of calves that had worn nose flaps, although the and THI between 26 and 29°C can pose danger to fenceline group spent more time eating than the animal wellbeing. Hahn (1999) states that ambient control group. Price et  al. (2003) also found that temperatures above 15°C can induce nominal per- fenceline separation prior to weaning reduced the formance losses in feeder calves gaining 0.8  kg/d. decline in eating time after remote separation. The Dry bulb temperatures during the 1130 and 1530 h results of Boland et  al. (2008) suggest that two- observation sessions after weaning were 22.3 and stage weaning with a fenceline separation may be 23.7°C for the A  and N calves, respectively, and a better alternative than nose flaps, since it reduced 13.1 and 14.3°C for the D calves (P  <  0.01). The the decline in time spent eating. A and N calves were also subjected to heat indices Upon weaning, it is common for producers of 25.5°C or greater on 3 of 4 observation days at to offer concentrate to calves to replace the nutri- both the mid-day and afternoon periods in each tion that had previously come from milk. We ini- year of the trial. The D calves, on the other hand, tially offered 1.4 kg per steer per d of a corn-based had less than 1 instance per year of heat index ex- concentrate and increased this to 2.3  kg per steer ceeding 25°C after weaning. Elevated temperatures per d over 3 d. There were no treatment differences and HI during the postweaning period for A and N in concentrate consumption and all calves readily may have caused these steers to rest more in shaded Translate basic science to industry innovation Comparison of three weaning strategies areas of the corral and to lie down in these areas three treatment groups was similar (Table  6, where the soil may have been cooler. The D steers P = 0.21). Weights of the three treatment groups would not have experienced the same need to cool remained similar through shipment to the harvest themselves. Mattachini et al. (2011) reported a nega- facility (P = 0.36) as did ADG (P = 0.78). Daily tive correlation between lying behavior in lactating DMI was also not affected by weaning strategy dairy cows and temperature-humidity index and (P  =  0.91). As a result, there were no differ- Heinicke et  al. (2019) reported increased activity ences in feed efficiency between the three treat- with decreased lying time. Cattle in these trials had ment groups (P  =  0.65). With the exception of access to shaded, free-stall housing; however, so ob- studies with early weaning, we are not aware of served behaviors may not be comparable to those other studies that have followed groups of calves of cattle provided with minimal shade. A clear ex- of similar age weaned by different weaning strat- planation for our observations is not apparent. egies through harvest. Thompson et  al. (2011) Observed rumination frequency was similar took ultrasound carcass measurements; however, (P  =  0.37) across treatments prior to and dur- they do not report feedlot gain or feed consump- ing nose flap placement. Calves were ruminating tion. Our data suggest that weaning strategy did at about 15% (SEM  =  3.4%) of observations. not impact growth beyond the backgrounding Following weaning, all treatment groups seemed period (42 d after weaning A and N) when calves to ruminate more with some days having observa- are of similar age. tion frequencies of approximately 20%; however, there were no overall treatment differences in ru- mination behavior with frequency means of 19.0, Carcass Characteristics 17.8, and 14.4% for A, N, and D, respectively, after Weaning strategy had minimal impact on car- weaning. Enriquez et al. (2010) reported treatment cass characteristics (Table  7). Carcass weight, x day interactions for rumination where rumination back fat thickness, and KPH fat percentage were increased for control calves on day 2 following not different among treatments. The D steers weaning before returning to preweaning levels on had slightly smaller ribeye area than A  steers day 4. Fenceline weaned calves had greater rumin- (P  =  0.04) with N steers being intermediary for ation frequency on the day after weaning and re- this characteristic. All three-treatment groups turned to preweaning frequency on day 4 after had ribeye area that was similar to current in- weaning. dustry average of 89.7  cm and fell within the optimal range for the food service sector for Growing and Finishing cooking time and tenderness (77.4–96.6  cm ) re- Following their quarantine, the steers began ported by Dunn et  al. (2000). These results are the growing phase of the trial and BW of the in agreement with those of Myers et  al. (1999) Table 6. Growth and finishing characteristics of steers weaned abruptly (A, 237 d age), after 7-d placement of a nose flap prior to weaning (N, 237 d age), or after a delay of 49 d (D, 286 d age) with standard errors (SEM) Parameter (units) A (SEM) N (SEM) D (SEM) BW* at start growing phase, kg 353 (4.2) 349 (5.1) 343 (3.9) BW at end growing phase, kg 505 (5.4) 507 (9.4) 494 (5.0) BW at end finishing phase, kg 610 (7.2) 594 (7.0) 601 (8.9) BW at harvest, kg 629 (7.4) 622 (9.3) 615 (7.3) ADG* growing phase, kg/d 1.8 (0.05) 1.8 (0.08) 1.8 (0.04) ADG finishing phase, kg/d 1.4 (0.05) 1.5 (0.09) 1.4 (0.05) ADG overall, kg/d 1.6 (0.03) 1.6 (0.04) 1.6 (0.03) DMI* growing phase, kg/d 10.7 (0.18) 10.5 (0.23) 10.5 (0.17) DMI finishing phase, kg/d 10.4 (0.29) 10.7 (0.33) 10.5 (0.28) DMI overall, kg/d 10.5 (0.18) 10.6 (0.23) 10.5 (0.18) Gain:feed, growing phase 0.17 (0.003) 0.17 (0.006) 0.17 (0.003) Gain:feed, finishing phase 0.14 (0.004) 0.14 (0.006) 0.14 (0.003) Gain:feed, overall 0.15 (0.002) 0.16 (0.003) 0.16 (0.002) *BW: body weight; ADG: average daily gain; DMI: dry matter intake. Translate basic science to industry innovation Freeman et al. Table 7. Carcass characteristics of steers weaned abruptly (A, 237 d age), after 7-d placement of a nose flap prior to weaning (N, 237 d age), or after a delay of 49 d (D, 286 d age) with standard errors (SEM) Parameter A (SEM) N (SEM) D (SEM) Dressing percentage, % 60.0 (0.30) 60.1 (0.37) 60.5 (0.29) Adjusted end weight, kg 636.6 (8.3) 626.8 (10.3) 618.8 (8.1) Back fat, cm 1.37 (0.03) 1.58 (0.04) 1.49 (0.03) Kidney, pelvic, heart fat, % 2.03 (0.09) 2.06 (0.13) 2.08 (0.09) 2 b a,b a Ribeye area, cm 92.7 (1.42) 90.2 (1.88) 87.0 (1.40) a a,b b Yield grade 2.90 (0.09) 3.19 (0.12) 3.22 (0.09) Marbling score 5.44 (0.17) 5.55 (0.23) 5.83 (0.17) Quality grade 17.00 (0.21) 16.91 (0.27) 17.31 (0.20) a,b Values without common superscripts differ (P < 0.05). *Adjusted end weight = hot carcass weight/mean dressing percentage. Marbling score: 5 = small amount, 6 = modest amount. Quality score 16 = select, 17 = low choice, 18 = average choice. and Meyer et  al. (2005) who showed that early weaning, especially when it is accomplished in the weaned calves that had been exposed to concen- absence of other stressors such as co-mingling and trate feeding for longer periods of time had an ad- transport, is not as stressful as people perceive it vantage at harvest over steers weaned at an older to be based on animal behavior, particularly when age. This principle could also apply to the com- the cattle are being managed in a rotational grazing parison of normal-aged and delay weaned cattle. system where they receive human contact multiple Thompson et al. (2011) reported no difference be- times per week. tween A and N steers in REA, backfat thickness, or marbling score their study. Delayed weaned ACKNOWLEDGMENTS steers had poorer yield grade than A  (P  =  0.02) The author wishes to acknowledge Mark in the present study, due to their smaller REA; Clements and all the staff at Cherry Research however, based on current grid marketing stand- Farm (Goldsboro, NC) and at Butner Beef ards, no Yield Grade discounts across treatments Cattle Field Laboratory (Bahama, NC) for their would be expected. The steers received an average assistance with this project. Without their con- quality grade of Low Choice. tinued support and hard work, completion of this study would not have been possible. We are grateful for consistent funding from the North IMPLICATIONS Carolina Cattle Industry Assessment for the dur- Results of this study imply that when steers ation of the project. Lastly, we are also grateful are followed to harvest, weaning strategy has little to Dr Philipe Moriel (Range Cattle Research and impact on the efficiency of production or on end Education Center, University of Florida, Ona, product quality. The presence of nasal lesions in 12 FL) for his assistance with analysis of blood sam- of 38 steers which received nose flaps suggests fur - ples for hormones. ther research into the animal welfare implications Conflict of interest statement. None declared. of this strategy may be warranted. This study also suggests that the producer who sells his/her cattle LITERATURE CITED after a brief preconditioning period should con- Arthington,  J.D., R.F.  Cooke, T.D.  Maddock, D.B.  Araujo, sider the weaning strategy chosen. Our data indi- P.  Moriel, N.  Dilorenzo, and G.C.  Lamb. 2013. 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Journal

Translational Animal ScienceOxford University Press

Published: Dec 24, 2020

Keywords: activity; behavior; carcass characteristics; hormones; weaning strategy

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