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Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 Effects of extended-release eprinomectin on productivity measures in cow–calf sys- tems and subsequent feedlot performance and carcass characteristics of calves † ‡ ,1,2 Claire E. Andresen,* Dan D. Loy,* Troy A. Brick, Lee L. Schulz, and Patrick J. Gunn* *Department of Animal Science, Iowa State University, Ames, IA 50011; Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA 50011; and Department of Economics, Iowa State University, Ames, IA 50011 ABSTRACT: The objective of this study was to ADG did not differ between treatments (P ≥ 0.34). estimate the impact of a single injection of extend- Incidence of pinkeye tended to be less (P = 0.06) ed-release eprinomectin on economically relevant for cows treated with EPR but was not different production variables in beef cows and calves as well for calves (P = 0.43). Conception to AI, overall as subsequent feedlot health, performance, and car- pregnancy rates, and calving interval were not dif- cass traits of calves compared with a traditional, ferent between treatments (P ≥ 0.45). A subset of short duration anthelmintic. Animals from 13 calves from each herd was sent to Tri-County Steer cooperator herds across seven states were stratified Carcass Futurity (TCSCF) feedlot for the finishing within herd and assigned to one of two treatments; phase. Calf BW did not differ at initiation of feeding injectable doramectin (DOR; Dectomax; n = 828) (P = 0.20). While EPR calves tended to be heavier or injectable eprinomection (EPR; Longrange; at reimplantation (P = 0.07), final BW and overall n = 832). Fecal samples were randomly collected ADG were not different between treatments (P ≥ from a subset of cows at both treatment and the 0.13). Health records indicated lower morbidity for end of grazing to evaluate fecal egg count (FEC). EPR calves (P = 0.05). Carcass performance includ- Continuous and categorical data were analyzed ing HCW, dressing percent, backfat, KPH, REA, using the MIXED and GLIMMIX procedures YG, were not different between treatment groups of SAS, respectively. Cow treatment body weight (P ≥ 0.12). However, EPR calves had a greater mar- (BW) and final BW were not different (P ≥ 0.40) bling score, greater average quality grade (P < 0.01), between treatments. There were no differences (P and higher proportion of calves that graded average ≥ 0.12) between treatments in cow ADG, change choice or greater (P = 0.03). Results of this study in BW, or body condition scores during the graz- indicate no difference in cow or preweaning calf ing season. While FEC at treatment did not differ performance, however, carcass quality in the feed- (P = 0.18), cows treated with EPR had lower final lot phase was improved. Thus, economic analysis FEC at the end of the grazing season (P = 0.02) and indicates opportunities for return on investment if a greater reduction of FEC over the grazing season animals treated with EPR have improved health sta- (P = 0.01). Calf treatment BW, weaning BW, and tus and/or carcass quality during the feeding phase. Key words: anthelmintic, deworm, economics, fecal egg count, feedlot, pregnancy Published by Oxford University Press on behalf of the American Society of Animal Science 2018. This work is written by (a) US Government employee(s) and is in the public domain in the US. This Open Access article contains public sector information licensed under the Open Government Licence v2.0 (http://www.nationalarchives.gov.uk/doc/open-government-licence/version/2/). Transl. Anim. Sci. 2018.XX:XX–XX doi: 10.1093/tas/txy115 Corresponding author: firstname.lastname@example.org Current address: Purina Animal Nutrition, LLC; INTRODUCTION email@example.com It has been well documented that gastrointes- Received May 29, 2018. Accepted November 1, 2018. tinal parasites can be detrimental to cattle health 1 Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 2 Andresen et al. and performance. Production parameters impacted health and performance, Tri-County Steer Carcass by parasitic infection include weight gain, repro- Futurity (TCSCF) cooperators were identified as ductive efficiency, health, feedlot performance, and cooperators for this study because of the retained carcass quality (Hawkins, 1993). Since the 1960’s, ownership platform (Reinhardt et al., 2009). anthelmintic treatment has been a staple in ruminant In May 2015, a Qualtrics survey (Qualtrics, production systems to mitigate production losses Provo, UT) was administered by TCSCF and Iowa caused by helminth infection. In cow–calf produc- State University to screen potential cooperator tion, anthelmintic treatment has been shown to herds. Survey questions were aimed at identifying improve cow BW and body condition scores (BCS), management styles, record keeping, and herd health increase overall breeding season pregnancy rates, protocols. Questions inquired about current para- and improve calf performance (Stuedemann et al., site control programs including if a parasite con- 1989; Wohlgemuth et al., 1990; Stromberg et al., trol program was in place, what type of dewormer 1997; Hersom et al., 2011). The effects of anthel- was used (i.e., pour-on or injectable), which classes mintic treatment during the feeding phase have been of cattle were commonly dewormed in the opera- shown to improve ADG, feed to gain (F:G), daily tion (i.e., cows, calves, or both), and postweaning dry matter intake, and final BW (Smith et al., 2000). parasite management of calves. Other questions Furthermore, studies have linked calfhood deworm- identified common production practices such as if ing treatment to improved lifetime performance and when body weights were typically recorded, if including growth, reproduction, and health (Mejia and when BCS were recorded, when calving sea- et al., 1999; Stacey et al., 1999; Clark et al., 2015). son typically began and ended, if calving data were In 2012, Merial, Inc. released an extended-re- recorded, and if pregnancy checks were conducted. lease version of the anthelmintic drug, eprinomec- In order to qualify for participation in the study, tin. This product label claims 100–150 d of parasite producers must have had a parasite control program protection with one injection. Evaluation of concen- in place as part of a herd health protocol and be tration of eprinomectin shows effective plasma con- able to provide accurate visual ID records for both centrations up to 150 d postadministration (Solls cows and calves. Birth records, including birth date, et al., 2013). Studies with stocker cattle have proven sex, and birth weight, for both the year of initial that extended-release eprinomectin effectively treatment (2016) and the subsequent calving season reduces worm burdens and improves weight gains (2017) must have been available. Producers must in this class of cattle (Rehbein et al., 2013a, 2013b, have had the ability to collect timely and accur- Clark et al., 2014). However, to date, little research ate measurements including cow and calf BW and has been published regarding the effects of extend- cow BCS at the time of treatment and at weaning. ed-release eprinomectin on cow–calf performance. Necessary reproduction data included pregnancy Therefore, the objective of this study was to assess checks for both spring- and fall-calving herds with economically relevant performance parameters in fetal aging if possible, AI dates (if applicable) as cow herds following administration of extended-re- well as length of bull exposure. Producers that lease eprinomectin at the start of the grazing sea- met minimum requirements were then selected for son and to assess subsequent feedlot performance participation in the study. It is important to note of progeny. We hypothesized that treatment of that producers participating in this study were not cows and calves with extended-release eprinomectin required to have any history of parasitic infection would improve cow performance and reproductive within their herd nor were they required to identify success and positively impact progeny performance the level of parasitic infection prior to the initiation compared to a short duration anthelmintic. of the study. Experimental Design MATERIALS AND METHODS Twelve cooperator herds located in seven states All procedures and protocols were approved (Iowa, Missouri, Indiana, Kentucky, Tennessee, by the Iowa State University Institutional Animal Ohio, and Georgia) participated in the study. The Care and Use Committee (3-16-8209-B). total number of animals enrolled in the trial was 1,768 cow–calf pairs and included both spring- and Survey fall-calving herds. Animals were stratified within Because one of the study goals was to fol- herd by cow age, calf birth date, calf birth BW, and low progeny through the feedlot phase to assess calf sex and assigned to one of two treatments; Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 Extended-release eprinomectin in beef cows 3 injectable doramectin (DOR; Dectomax, Zoetis, calves only received a single dose of their respective Animal Health, Parsippany, NJ; n = 879) or inject- anthelmentic throughout the duration trial. The able eprinomection (EPR; LongRange, Merial, two-tier design implemented in this study allowed Duluth, GA; n = 889) at a rate of 1 mL/50 kg. for unique evaluation of both parasite burden and Treatments were administered in the spring of 2016 performance response. In order to maintain sep- during pasture turnout (Table 1). Average pasture arate parasite burdens relative to treatment, tier turn-out date for participating herds was 16 May one was implemented. This design prevents EPR 2016. On average, treatments were administered on cows from potentially diminishing parasite loads 9 May 2016 with a treatment range of March 23rd that DOR may otherwise have been exposed to. to June 15th. Individual and overall herd charac- However, because reproductive variables were of teristics at the time of treatment are presented in interest in this study, tier two was implemented Table 1. Overall, at treatment administration, cows in order to evenly apply variables, such as natural averaged 5 ± 3.0 yr of age, weighed 568 ± 92 kg service sires, between treatment groups. Although with an average BCS of 5.4 ± 0.9, and were 69 ± 33 forage data including quality and type were not d postpartum (DPP). One hundred and eight pairs collected, tier two allowed for mitigation of for- (n = 51 DOR; n = 57 EPR) were removed from the age type and quality variables that often confound trial due to nontreatment-related issues including results in replicated grazing studies. It is impor- mortality, morbidity, or culling during the grazing tant to note that previous studies have successfully season. detected performance and parasite load differences The study consisted of two different treatment between anthelmintic treatments that were comin- tiers. In tier one, only cows were treated. Following gled in a grazing environment (Clark et al., 2013; treatment, EPR cows were managed on similar but Watson, 2016). separate pastures from DOR cows and treatments were not comingled at any time between treatment Production Measures and weaning. Moreover, cows were not grazed in Performance. Cow body weights (BW) and pastures where the opposite treatment had grazed body condition scores (BCS; 1–9; Wagner et al., previously during the grazing season. In tier two, 1988) were taken at the time of treatment and again EPR cows and DOR cows were comingled from at the end of the trial. The end of the trial was dif- the start of the trial. At approximately 90 d of age, ferentially determined based on calving season. For per label instructions, calves were treated with the spring-calving cows, end of trial was considered identical product as their dams. Both dams and Table 1. Age, calving date, birth weight, treatment date, days postpartum, BW, and BCS of cows from cooperating herds enrolled in the study Julian calving Calf birth Dam treatment 2 3 4 Mean age, years date, mean and weight, mean date , mean and Days postpartum , Mean BW, kg Mean BCS , Herd n (range) range and range range mean and range (range) (range) 1 75 5.4 (2–13) 56 (16–97) 36 (25–49) 160 (160–161) 104 (63–144) 576 (431–750) 5.5 (4.0–9.0) 2 51 4.8 (2–11) 58 (23–101) --- 124 (121–128) 69 (27–105) 582 (452–716) 6.0 (4.0–8.0) 3 40 5.1 (3–10) 90 (12–201) --- 91 (---) 0.6 (−110–79) 591 (448–740) 6.2 (4.0–8.0 4 164 4.9 (2–13) 23 (−2–57) 33 (21–49) 89 (81–104) 67 (26–93) 541 (350–769) 5.8 (4.0–8.0) 5 194 4.8 (2–12) 18 (−18–109) --- 139 (122–153) 120 (44–166) 621 (376–858) 4.3 (3.0–6.0) 6 67 4.2 (2.0–11) 72 (125–136) --- 128 (125–136) 56 (19–91) 658 (372–803) 4.3 (3.0–6.0) 7 402 5.7 (2–14) 127 (16–290) 37 (18–52) 150 (116–166) 69 (31–143) 522 (306–796) 5.7 (3.3–8.0) 8 129 5.2 (2–15) 142 (19–291) 39 (23–56) 140 (126–147) 60 (14–128) 621 (495–782) 5.4 (4.0–7.3) 9 188 6.2 (2–14) 109 (51–268) 37 (27–45) 131 (130–133) 49 (7–79) 602 (413–759) 5.4 (4.3–7.3) 10 118 4.3 (2–16) 85 (45–148) 34 (20–49) 127 (126–132) 43 (−22–87) 566 (395–744) 5.5 (4.0–7.5) 11 90 3.9 (2–10) 81 (57–112) 33 (21–43) 126 (---) 45 (14–69) 537 (372–779) 5.7 (4.0–8.0) 12 248 5.8 (2–15) 110 (79–167) 35 (16–51) --- --- --- --- Overall 1,766 5.3 (2–16) 89 (−19–291) 36 (16–56) 133 (81–166) 70 (−110–166) 568 (306–858) 5.4 (2.0–9.0) Herds were located in seven different states. Julian date of treatment within a herd. Days postpartum at anthelmintic administration. Body condition score on 1 to 9 scale (1 = emaciated and 9 = obese; Wagner et al., 1988). Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 4 Andresen et al. as time of weaning. For fall-calving herds, end of n = 134 EPR) were taken of the side used in the live the trial was considered when pairs were removed analysis for fly count confirmation. from pasture. Calves that were in tier two of the Reproduction end points. For all herds, overall trial were weighed at the time of treatment (n = 543 breeding season pregnancy rates were collected for DOR; n=543). All calves in the study were weighed both spring and fall herds (n = 828 DOR; n = 832 at the time of weaning (n = 828 DOR; n = 832 EPR). Of participating herds, six producers imple- EPR). Birth weights of fall calves (n = 79 DOR; mented AI protocol. Where applicable, conception 73 EPR) were evaluated as a response variable to rates to AI were analyzed (n = 334 DOR; n = 327 anthelmintic treatment. It is well established that EPR). Calving distribution for the 2017 calving nutritional status during gestation plays a crucial season was evaluated as well as calving interval role in fetal development and postnatal progeny between 2016 and 2017 calving for all spring-calv- performance. Undernutrition, such as often seen ing herds (n = 610 DOR; n = 611 EPR). during a parasitic infection, can be detrimental to development and lifetime performance of an ani- Feedlot and carcass data. After weaning, calves mal by decreasing birth weight, impacting devel- were managed at individual cooperating locations opment during gestation, and ultimately altering per the standard operating procedure of each farm. postnatal metabolism and performance (Funston Although postweaning management of calves was et al., 2009; Canton and Hess, 2010). Forty-four not controlled as part of the study, requirements calves were removed from final analysis due to established by TCSCF for calves entering the pro- administration of the incorrect anthelmintic treat- gram ensured comparable health management ment (n = 21 DOR; n = 23 EPR). between producers. To qualify for TCSCF, calves must be weaned for a minimum of 30 d, be castrated Fecal samples. Fecal samples were taken from a and dehorned, and treated for internal and external subset of five herds. Approximately 15 cows per parasites. Calves must also have been administered treatment were randomly selected at each location two doses of the following vaccinations: infectious and were sampled at the start (n = 75 DOR; n = 69 Bovine rhinotracheitis (IBR), Bovine viral diar- EPR) and end (n = 70 DOR; n = 65 EPR) of the rhea virus (two types; BVD), parainfluenza (PI3), trial to measure initial and final fecal egg counts Bovine respiratory syncytial virus (BRSV), and sev- (FEC). Samples collected included both spring- en-way blackleg. and fall-calving herds as well as herds from both A subset of calves from each herd at the discre- experimental tiers. All fecal samples were shipped tion of the cooperator was then sent to a TCSCF to Texas A&M Diagnostic Lab for analysis of FEC feedlot for the finishing phase. Calves arrived at as well as coproculture if warranted. the feedlot between 16 October and 22 December Health outcomes. Available herd health records 2016 (n = 238 DOR; n = 259 EPR). Upon arrival, were used to analyze incidence of pinkeye over the calves were vaccinated with a five-way and sev- course of the grazing season. Health records were en-way. Calves were also administered a dewormer, submitted from two herds and both indicated treat- implanted, tagged, and weighed. Cattle were tran- ment records for pinkeye for cows (n = 323 DOR; sitioned to an 80% concentrate diet over a 28-d n = 325 EPR) and calves (n = 312 DOR; n = 308 period. While at TCSCF, feedlot performance EPR). In July, fly counts were conducted on a subset and health were monitored. Finished cattle were of five herds to evaluate fly burden. Herds included harvested between 21 March and 6 July 2017. in the analysis consisted of both experimental tiers Following slaughter, carcass data were collected. as well as both spring- and fall-calving herds. Live Thus, feedlot performance, morbidity, and carcass fly counts were evaluated in the pastures (n = 151 parameters were analyzed. DOR; 150 EPR) in mid-July. Within a pasture, animals were selected at random and fly burdens Economic Analysis were estimated from a single side of the animal and Extended-release eprinomectin (EPR) is mar- included face, shoulders, back, and legs. Flies were keted as offering novel performance response and counted individually until the number exceeded 25, has a label-claim for lengthened protection. However, and then counted in groups of 5 (Steelman et al., the cost of this product is in an added out-of-pocket 1997). Estimations from a single side were then dou- expense to producers compared to conventional bled to obtain a full body estimate of fly burden. At parasite control products. Therefore, an economic the time of live evaluation, pictures (n = 133 DOR; Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 Extended-release eprinomectin in beef cows 5 analysis evaluating production responses to anthel- RESULTS AND DISCUSSION mintic treatment and thus, economic impact on pro- The objective of this study was to measure a ducers, was conducted. The goal of this analysis was multitude of standard, economically relevant pro- to evaluate the initial cost of treatment and the dif- duction variables of beef cows and calves as well ferential performance needed for producers to make as subsequent feedlot health, performance, and up the increased cost of EPR compared to a con- carcass traits of those calves from herds that were ventional parasite control product like DOR. administered extended-release eprinomectin com- The economic model used for the cow–calf pared to dectomax 1% injectable at the labeled enterprise analysis was a partial budget (Texas dose rate. Cooperative Extension, 2002). For this analysis, a treatment herd was standardized to 100 cow–calf Cow Performance pairs. Margin over cost was set at 0% to determine breakeven prices and labor was considered equal Cow performance data are presented in Table 2. between the two treatment groups. A standard Initial and final BW did not differ due to treatment weaned calf percentage of 90% was used for both (P ≥ 0.32). In addition, change in BW over the treatments. An average weaning weight of 238 kg course of the trial was not different and there was was used for both the treatments. In addition to the no difference in change in BW as a percent of initial baseline analysis, alternative scenarios were ana- BW which correlated into no differences in ADG lyzed by increasing or decreasing calf prices by 20% (P ≥ 0.12). Subsequently, there were no differences while holding all other variables constant. in either initial or final BCS (P ≥ 0.23) as a result An enterprise budget was used for the analysis of treatment. While previous literature has found of the feedlot data (Ag Decision Maker, 2017). weight differences (Ciordia et al. 1982; Stuedemann Budgets for each treatment group were created et al. 1989), comparisons have predominately been using actual records and prices reported by TCSCF. made between dewormed groups and nontreated controls. However, the present study compares dif- Statistical Analysis ferences between two groups treated with anthel- mintics that differ in duration of efficacy. Results Cow–calf analysis. Performance data and calv- from a similar study (Backes et al., 2016) have ing interval were analyzed using the MIXED reached comparable conclusions showing no over- procedure of SAS 9.4. Conception to AI, overall all weight difference between groups treated with breeding season pregnancy rates, calving distribu- a conventional short duration oral oxfendazole or tion, and health outcomes were analyzed using the extended-release eprinomectin. However, Myers GLIMMIX procedure of SAS 9.4. Cow, or calf (1988) has suggested that increased performance in when appropriate, was the experimental unit for the the form of improved milk production or reproduc- analysis. The model included fixed effects of treat- tive success following anthelmintic treatment may ment, season, tier, calf sex when appropriate, and confound cow weights so that weights may not be included the random effect of pasture nested within a meaningful production parameter when studying location to account for variation within and across parasite control in cow–calf production. herds relative to management and weather. Feedlot performance and carcass quality ana- Health Outcomes lysis. Feedlot and carcass performance were ana- lyzed using the MIXED procedure of SAS 9.4. Previous studies have indicated some level of fly Quality grade distribution and morbidity were control associated with treatment with extended-re- analyzed using the GLIMMIX procedure of SAS lease eprinomectin in grazing environments (Vesco 9.4. Calf was the experimental unit for the analysis. et al., 2015; Trehal et al., 2017). Anecdotal evidence The model included fixed effect of treatment, tier, has found reduced fly burdens with lower incidence season, a covariate of calf sex, and included the of pinkeye in grazing cattle that were treated with random effect of pasture nested within producer to extended-release eprinomectin. While extended-re- account for variation in management. lease eprinomectin is not labeled for fly control, Tier and season were tested as main effects and one of the objectives of the current study was to for interaction and removed if no interaction was evaluate claims of reduced fly burden and inci- detected. Significance was declared at P ≤ 0.05 and dence of pinkeye. An evaluation of fly burden in tendencies 0.05 ˂ P ≤ 0.10. the current study indicated no differences between Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 6 Andresen et al. EPR and DOR treated cows (P ≥ 0.62; Table 3). (DOR = 8.4%; EPR = 4.6%; P = 0.06), however, These results are similar to those reported by this reduction is not explained by differences in fly Watson (2016), where there were no differences in burden. When evaluating incidence of pinkeye in fly counts between control, combination treatment calves, there was no difference in pinkeye treatment of oxfendazole and moxidectin, or extended-re- between treatment groups (P = 0.43). lease eprinomectin-treated calves comingled during There has been speculation that the fly con- a 100-d stocker period. Interestingly, EPR cows trol associated with extended-release eprinomectin in the current study tended to have a lower inci- is correlated with the reduction in pinkeye within dence of pinkeye as reported by treatment records treated herds. Fly control following treatment with extended-release eprinomectin is believed Table 2. Performance of cows treated with different to be a result of residue in manure pats that dis- anthelmintic treatments during the grazing season rupt egg and larval development of fly species that use the manure to procreate, in a manner similar Treatment to an insect-growth regulator (IGR). While treat- Item DOR EPR SEM P-value ment with extended-release eprinomectin has been BW, kg shown to reduce horn fly burdens in grazing stocker Treatment 577 578 11.4 0.85 cattle (Trehal et al., 2017), there is no data on its Weaning 587 590 10.8 0.40 effectiveness on face flies, the main transmitters of Change in , kg 9 12 4.7 0.13 4 pinkeye within a grazing herd. Furthermore, face Change in , % 1.95 2.67 0.81 0.12 flies can travel long distances and spend minimal Performance ADG , kg 0.05 0.08 0.04 0.23 time on an animal, making control of these pests BCS difficult with products such as IGR (Antonelli and Treatment 5.57 5.57 0.07 0.99 Ramsay, 2014). Therefore, it is hard to identify a Weaning 5.58 5.60 0.09 0.59 causal relationship between fly control and pinkeye Change in 0.00 0.02 0.08 0.67 with this product. More research is necessary to 1 verify and determine the relationship, if one exists, Treatment: DOR = doramectin (Dectomax; Zoetis Animal Health, Parsippany); EPR = eprinomectin (LongRange; Merial, Duluth, GA). between these two variables. Larger SEM presented (n = 828 DOR; n = 832 EPR). P-value: Significant P ≤ 0.05; Tendency 0.05 < P ≤ 0.10. Reproduction Calculations based on weight changes from treatment to weaning/ end of grazing season. Marked improvement in reproductive success of both mature cow herds and developing heifers Table 3. Health and reproductive success of cows have been noted following administration of anthel- treated with different anthelmintic treatments dur- mintic treatment when compared to nontreated ing the grazing season controls (Stuedemann et al., 1989; Larson et al., Treatment 1995; Stromberg et al., 1997; Loyacano et al., 2002; Item DOR EPR SEM P-Value Andresen et al., 2017). Improved conception rates FEC that have been previously reported have frequently Initial 2.07 2.97 0.49 0.18 been in conjunction with increases in BW and BCS Final 1.76 0.71 0.34 0.02 indicating an improvement in the nutritional status Change in −0.30 −2.12 0.60 0.01 of the animal. Given the low priority of function Health of reproductive processes such as cyclicity and ini- Cow Pinkeye, % 8.4 4.6 --- 0.06 tiation of pregnancy (Short and Adams, 1988), it Live Fly Counts 62 60 11.3 0.62 is plausible that the improved nutritional status Picture Fly Counts 50 58 11.8 0.69 often associated with anthelmintic treatment could Reproduction, % (no./no.) improve reproductive function, especially dur- Conception to AI 47 (157/334) 50 (164/327) --- 0.51 ing early lactation when nutritional demands are Pregnancy Rate 88 (729/828) 88 (733/832) --- 0.45 increased. The extended days of parasite protection Calving Interval , days 371 370 2.1 0.72 claimed by extended-release eprinomectin allows Treatment: DOR = doramectin (Dectomax; Zoetis Animal Health, the possibility to improve nutritional status for a Parsippany); EPR = eprinomectin (LongRange; Merial, Duluth, GA). longer period before reinfection with GIN during Larger SEM presented (n = 828 DOR; n = 832 EPR). 3 a critical time when a cow is nursing and trying to P-value: Significant P ≤ 0.05; Tendency 0.05 < P ≤ 0.10. conceive. When evaluating reproductive success of Pregnancy rate for 2016. Calving interval from 2016 to 2017 calving. cow herds in the current study (Table 3), there were Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 Extended-release eprinomectin in beef cows 7 no differences in conception to AI (DOR = 47%; overall reduction in FEC compared to DOR cows EPR = 50%; P = 0.51) or overall breeding sea- (P = 0.01). However, FEC of both treatments at son pregnancy rates (DOR = 88%; EPR = 88%; both treatment and at final performance meas- P = 0.45). Contrarily, Backes (2016) reported dams urement were far below a threshold that would treated with oral oxfendazole tended to have higher be indicative of clinical parasitism (Bagley et al., overall conception rates when compared to cows 1998). We believe that a lack of parasitic infection treated with EPR. However, neither the current during the grazing season may have resulted in a study nor Backes (2016) reported differences in lack of performance differences in this study. Low ADG or BW over the course of the grazing sea- FEC may be a reflection of the types of herds that son, indicating nutritional status was not greatly were selected to participate in this study. Because improved between the short duration group and of the stringent requirements to qualify for partici- the extended protection groups in these studies. pation, herds selected were uncommonly well-man- Evaluation of calving distribution in the calving aged which likely contributed to low overall FEC. season following treatment indicated no differences In similar studies, consisting of treatments that in the number of calves born in the first 21 d as a included positive control groups and comingled result of treatment (P = 0.98). Analysis of subse- treatments, both Pfeifer et al. (1999) and Ward quent 21-d intervals showed no differences between et al. (1991) saw similar FEC during the course of treatment in the number of calves born in each the respective trials and reported no performance interval (P ≥ 0.33). As expected, with no differences differences following anthelmintic treatment. This in calving distribution, there was also no difference indicates, in agreeance with previous work, the in calving interval between the 2016 and 2017 calv- level of parasitic infection in the current study may ing season (DOR = 371 d; EPR = 370 d; P = 0.72). not have been high enough to elicit a production response. However, it should be noted that Clark et al. (2013) was able to detect significant differences Fecal Egg Counts in performance between commingled ivermectin and extended-release eprinomectin-treated stocker Fecal samples were collected from a subset of calved that had FEC of 5.14 and 0.90, respectively. five cooperator herds at the start and end of the grazing season for evaluation of FEC as well as coproculture if warranted. Of the five herds sam- Calf Performance pled, three DOR and four EPR groups warranted Results for calf growth and performance are coprocultures from samples collected at the start reported in Table 4. There were no differences in of the grazing season, which identified the percent birth BW for calves regardless of tier or calving of each roundworm species found in the fecal sam- season (P = 0.57). Because fall-calving herds were ple. Species identified in DOR groups were pre- treated in the spring while cows were pregnant, birth dominantly comprised of Cooperia (100%, 81%, weights of fall calves were analyzed as possible fetal and 76%) and Haemonchus (0%, 19%, and 24%). programing response to treatment. However, ana- Similarly, EPR groups consisted primarily of lysis of birth weights of fall calves indicated no Cooperia (100%, 100%, 82%, and 55%) followed by difference between treatments (P = 0.43; data not Haemonchus (0%, 0%, 18%, and 12%). Other species shown). Calf BW at the time of treatment for calves detected in the EPR group were Oesophagostomum in tier two was not different (P = 0.50). Likewise, (0%, 0%, 0%, and 12%) and 18% of larvae cultured weaning weights were not different between the two were too damaged to identify. No coprocultures treatment groups regardless of tier or calving season were warranted for fecal samples taken at the end (P = 0.75), although as expected there was a sea- of the grazing season. son effect (P ≤ 0.01) where fall calves were lighter Fecal egg count data are reported in Table 3. at weaning than spring calves. Subsequently, ADG Efficacy is most commonly measured using fecal between time of treatment and weaning was not dif- egg reduction tests (FECRT), which compares ferent (P = 0.28), and overall preweaning ADG did FEC before and after treatment with an anthelmin- not differ due to treatment (P = 0.57). While little tic to measure the reduction in or elimination of comparable literature exists for evaluation of a short fecal egg shedding (Taylor et al., 2002; Coles et al., duration and extended-release anthelmintic, Backes 2006). While initial FEC were not different between (2016) found increased weaning weight for calves treatment groups in this study (P = 0.89), final FEC from dams treated with oral oxfendazole compared were lower (P = 0.02) in EPR cows compared to with calves from dams treated with extended-release DOR cows. Subsequently, EPR cows had a greater Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 8 Andresen et al. Table 4. Performance and health of calves who Table 5. Feedlot and carcass characteristics of were treated with different anthelmintic treatments calves that were treated with different, preweaning during the grazing season anthelmintic treatments 1 1 Treatment Treatment 2 3 Item DOR EPR SEM P-Value Item DOR EPR SEM P-value BW, kg BW, kg Birth 35 35 0.6 0.57 Initial 347 354 9.1 0.23 Treatment 142 141 7.4 0.50 Reimplant 432 443 7.6 0.08 Weaning 231 232 5.5 0.75 Final 545 550 6.8 0.27 Performance, kg Performance, kg Treatment ADG 1.02 1.04 0.04 0.34 ADG 1.53 1.53 0.15 0.91 Weaning ADG 1.05 1.05 0.02 0.66 Health Health, % Treated, % 22.4 13.6 --- 0.06 Pinkeye 18.6 21.1 --- 0.43 Carcass Quality HCW , kg 341 343 4.4 0.43 Treatment: DOR = doramectin (Dectomax; Zoetis Animal Health, Dress , % 61.5 61.8 0.00 0.20 Parsippany); EPR = eprinomectin (LongRange; Merial, Duluth, GA). Backfat, cm. 1.37 1.35 0.05 0.72 Larger SEM presented (n = 807 DOR; n = 809 EPR). KPH , % 2.29 2.22 0.05 0.06 P-value: Tendency 0.05 < P ≤ 0.10. 8 2 Ribeye area , cm. 81.76 82.15 0.94 0.58 Actual weaning weight. Yield grade 2.49 2.55 0.08 0.35 Calculation based on weight change from time of anthelmintic Marbling score 1083 1097 9.23 0.13 treatment to weaning. Quality grade 12.30 12.52 0.10 0.03 Calculation based on weight change from birth to weaning. % QG Distribution eprinomectin. While milk production has been pre- Avg choice or Higher 40.38 51.43 --- 0.03 Low choice 47.31 41.43 --- 0.63 viously implicated in improved performance of Select and lower 12.31 7.14 --- 0.37 preweaned calves (Frechette and Lamothe, 1981; Ciordia et al., 1982; Stromberg et al., 1997), a lack Treatment: DOR = doramectin (Dectomax; Zoetis Animal Health, of performance differences in calves makes it an Parsippany); EPR = eprinomectin (LongRange; Merial, Duluth, GA). unlikely mechanism in the present study. Likewise, Larger SEM presented (n = 238 DOR; n = 259 EPR). low FEC found in cows suggest low worm burdens, P-value: Significant P ≤ 0.05; Tendency 0.05 < P ≤ 0.10. Hot carcass weight. possibly a result of well managed pastures, which Dressing percent. may have correlated to low levels of parasitic infec- Kidney, pelvic, heart fat. tion in calves. However, preweaning anthelmintic 7 0 0 0 Marbling score: small: 1,000 , modest: 1,100 , moderate: 1,200 , etc. treatment may have implications for improved per- 8 - 0 + USDA quality grade: 12: Choice , 13: Choice , 14: Choice , etc. formance later in both stocker and feedlot phases. Percentage of steers in each treatment by quality grade, within Stacey et al. (1999) found that preweaning treatment treatment total is 100%. with a sustained-release ivermectin bolus improved reimplantation approximately 50 d after initiation of stocker weight gains compared to calves treated feeding showed a tendency for EPR treated calves to with a conventional ivermectin pour-on. Clark weigh more (P = 0.07). While not statistically differ- et al. (2015) found that calves entering the feedlot ent (P = 0.13), EPR-treated calves did finish with a with a higher worm burden had reduced growth, slight weight advantage compared with DOR calves. compromised immunocompetency, and altered car- Although EPR calves finished with slightly heavier cass composition compared to steers with low FEC weights throughout the feeding period, this did not even though both groups were treated upon feedlot correlate into differences in ADG (P ≥ 0.31) between arrival. Furthermore, Clark et al. (2015) suggest that treatments. However, when evaluating health of not only do calves with a lesser parasite burden have calves in the feedlot, EPR calves were treated for var- improved preweaning performance, but that early ious health issues fewer times compared with DOR parasite protection may improve lifetime production. calves (P = 0.05) indicating improved health status. While all essential components of the immune system Feedlot Performance and Carcass Characteristics are present at birth, full functionality of immunity is not possibly until 2–4 wk of age and may continue to Feedlot performance and carcass measurements develop through puberty (Wilson et al., 1996; Chase are presented in Table 5. There was no difference in et al., 2008). Because DOR calves were protected from BW between DOR and EPR calves at initiation of the parasitic infection for a shorter period of the grazing feeding period (P = 0.20). Subsequent BW taken at Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 Extended-release eprinomectin in beef cows 9 season, as were their dams, exposure to parasites analysis include cow BW, overall breeding season may have occurred. Because parasites can impair or pregnancy rates, calving interval, calving distribution, even inhibit immune response (Gomez-Munoz et al., and calf weaning BW. As seen by production meas- 2004), an infection during this critical stage of devel- urements presented in Tables 1 and 2, little variation opment may have resulted in impaired development exists between treatment groups. Overall breeding of the immune system thus impacting lifetime immu- season pregnancy rates were not different indicating nocompetency. Although FEC in this study were low, a lack of evidence for increased return on investment calves are more susceptible to parasites, and although through increased calf crop. Likewise, calving inter- immediate performance was not impacted, disrup- val and calving distribution were not different, and tion of immune development may have been occurred there were no differences in calf performance. resulting in higher feedlot morbidity. A lack of differences in the current study pro- Subsequent carcass measurements showed no vides little opportunity for EPR cows to recoup the differences due to treatment including hot carcass increased cost of treatment during the preweaning weight (HCW), backfat (BF; P ≥ 0.22). Likewise, phase. Therefore, the cow–calf analysis sought to ribeye area (REA) and yield grade (YG) were simi- determine increased production, in kilograms of calf lar (P ≥ 0.60) between treatments. Calves treated with weaned, necessary for the respective treatments to be EPR tended to have a lower kidney, pelvic, and heart indifferent. Because treating with DOR is considered fat (KPH; P = 0.06). While there was no difference a conventional practice, the improved performance (P = 0.13) in marbling score, there was a difference needed by EPR calves in order to negate the cost dif- in quality grade distribution where EPR calves had a ference between treatments was also evaluated. greater percentage of carcasses grade average choice The partial budget for this analysis is organized or higher compared to DOR (38.4% DOR; 49.7% into two categories—expenses and income associ- EPR; P = 0.03). However, there were no differences ated with the change. In the present study, this con- in the number of carcasses that graded low choice siders a change from DOR to EPR treatment. or select and lower (P ≥ 0.37). Gardner et al. (1999) Expenses. Because expenses such as forage, feed, reported that feedlot morbidity results in a reduc- labor, and reproduction were the same irrespective tion in quality grade, with a higher percentage of of treatment, only costs associated with differences steers identified as sick grading Standard. Therefore, in anthelmintic treatment were considered. Based reduced morbidity and improved quality grade create on drug prices at the time of treatment, DOR potential for a greater return on initial anthelmintic costs $0.32/cc and EPR costs $1.38/cc. The aver- treatment. The results of this study are in agreeance age amount of medicine administered for cows and with those of Gardner et al. (1999) where DOR calves was 12cc and 3cc, respectively, for both the calves had a higher incidence of morbidity, resulting treatments. This resulted in a cost of $5.01 per cow– in an increased health cost, and had a lower average calf pair treated with DOR and a cost of $21.39 per quality grade as well as fewer calves grading average cow–calf pair treated with EPR. Cost difference choice or higher compared with healthier EPR calves. between EPR and DOR treatments was $16.38/pair. These results are in line with the previous stud- ies. Clark et al. (2013) found that calves treated Income. Income was determined by evaluating with extended-release eprinomectin did not have pounds of calf weaned at the market price on the improved feedlot performance or carcass character- average date of weaning for cooperating herds. istics. Likewise, Backes (2016) saw no difference in A market price of $3.40/kg (Iowa auction average HCW, marbling score, backfat, KPH, YG, or qual- for Sept. 2016) was used (USDA-AMS, 2016). ity grade distribution between calves treated with Results from the economic analysis are reported extended-release eprinomectin or oral oxfendazole in Table 6. This analysis indicates that EPR cows at weaning. Again, low FEC at initiation of the would need to wean calves with a 4.8 kg weight present study may have resulted in a lack of perfor- advantage over DOR calves in order to eliminate mance throughout all phases of production. the difference in cost between treatments. For pro- ducers to recoup the cost of the specific anthelmin- Economic Impact, Herd Level tic in cow–calf production, DOR and EPR calves Cow–calf. Performance responses were evaluated would need to add 1.5 and 6.3 kg by weaning, for differences in economic value between treatment respectively. The sensitivity of kilograms of weaned groups (Beef Cattle Decision Aids, 2002). Variables calf required to pay for the cost of anthelmintic considered as economically relevant in the cow–calf treatment at alternative calf prices are reported Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 10 Andresen et al. Table 6. Economic analysis and breakeven weight cows had the potential to have an increased return for calves and cull cows treated with different of $9.23/head (Table 6). It is also important to anthelmintic treatments during preweaning note the reduction in incidence of pinkeye in EPR cows. This also provides an opportunity, through Treatment reduced health and labor costs, to increase returns DOR EPR Difference on the initial cost of anthelmintic treatment. Thus, Herd size 100 100 --- improved performance in the form of added weight Cost of Treatment $5.01 $21.39 $16.38 for either weaned calves or cull cows and improved Average WW, kg 238 238 --- herd health have the potential to improve return on Breakeven weight needed , kg investment for preweaning anthelmintic treatment $2.73/kg 1.8 7.9 6.0 for the cow–calf enterprise. $3.40/kg 1.5 6.3 4.8 $4.06/kg 1.2 5.3 4.0 While not evident in the current study, per- Average cull cow weight, kg. 577 571 6 formance increases necessary to offset cost of Cull cow value , $/hd $902.41 $893.78 $9.23 treatment during the preweaning phase may be possible in alternative environments such as those Treatment: DOR = doramectin (Dectomax; Zoetis Animal Health, with higher levels of parasitic infections. Data eval- Parsippany); EPR = eprinomectin (LongRange; Merial, Duluth, GA). uating the use of extended-release eprinomectin Cost difference that must be made up by EPR calves in order to breakeven with a conventional treatment. compared to a conventional ivermectin injectable in Budget utilized from Beef Cattle Decision Aids (2002). fall-calving beef herds has shown improvements in Added weaning weight necessary above the average for treatments conception to AI as well as overall breeding season to breakeven at various market prices. pregnancy rates (Andresen et al., 2018). Therefore, Weighted average market price of medium to large, frame 1, 227– improvements in reproductive efficiency manifested 249 kg fed calves for Iowa auctions on September 2016. as greater overall season pregnancy rates following Value calculated based on October 2016 Boning cow 544–907 kg prices reported from Sioux Falls, SD. anthelmintic treatment may provide opportunities for a greater return on investment. in Table 6. Results of the sensitivity analysis indi- The same study also found reduced calving cate, as expected, that the added weight necessary interval and a shift in calving distribution in the for a producer to recoup the cost of anthelmintic calving season following initial anthelmintic treat- treatment was highly variable depending on the ment for cows treated with EPR, as well as increased market price. weaning weights for their calves. Thus, a reduced While it may not be efficient to retain open calving interval and a shift in calving distribution females in a herd, attention to management and following anthelmintic administration may improve marketing of cull cows can impact profitability. the probability of weaning heavier calves. Data Cull cows can represent up to 10–20% of total from Funston et al. (2010) show that steers and revenue within the cow–calf enterprise (Peel and heifers born in the first 21-day calving period per - Doye, 2008). While marketing is important, man- form better than cohorts born in later calving peri- agement strategies alone can increase cull cow ods. Shifting calving distribution may also improve value by 25–45% (Peel and Doye, 2008). Increasing cow pregnancy rates by increasing the postpartum pounds of animal sold can result in increased rev- recovery time. This may result in a larger calf crop enue at comparable prices. Therefore, the use of as well as increased pounds of calf weaned per cow. a specific anthelmintic could improve cow–calf These data indicate alternative conditions to the returns through increased cull cow values. While ones in the current study have the potential to gen- there were no differences in cow BW at weaning, erate a greater return on investment following treat- evaluation of BW differences between open cows ment with EPR. However, it is important to note in each treatment group were analyzed for oppor- that improvements in returns based on improved tunities for increased cull cow value. Analysis performance will be highly dependent on the eco- shows a slight weight advantage for open DOR nomic conditions at the time calves are marketed. cows compared to open EPR cows (577 kg DOR; It is also important to note that estimates from 571 kg EPR; data not shown) (Table 4). This this analysis are likely conservative. The compari- slight weight advantages creates an opportunity son in the current study was made between extend- for producers to realize a greater return, on aver- ed-release eprinomectin and a single treatment of age, from cull animals treated with DOR. With an a short duration anthelmintic. Because the goal of average cull cow price of $1.56/kg from October this study was not to compare the effectiveness of 2016 (Sioux Fall, SD) (USDA-AMS, 2016), DOR deworming, no comparison was made using a short Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 Extended-release eprinomectin in beef cows 11 duration anthelmintic multiple times throughout an opportunity for slightly higher profits ($200.11 the grazing season to create an equal number of DOR; $227.22 EPR) per animal. protected days as EPR, which would have increased initial treatment costs for DOR. The goal of the Retained Ownership current study was to evaluate extended-release As seen by slightly higher returns for EPR calves eprinomectin compared to conventional deworm- in the feedlot, administering EPR preweaning may ers in common production settings where deworm- be able to make up the cost difference between the ing typically occurs once during the grazing season two anthelmintic treatments. which was also the basis of the economic analysis For producers operating on a retained owner- conducted. ship platform, like cooperating herds in this study, Feedlot. The enterprise budget for this analysis opportunities to capitalize on a higher calfhood used actual income and expense records for each deworming investment are much greater. While a treatment group and prices reported by TCSCF. lack of differences in the cow–calf portion of this study indicated little potential for improved returns Expense. Costs including feed, interest, death loss, for cow–calf production alone, improved immu- and yardage were assumed equal between treat- nocompetency and higher final BW of EPR calves ment groups as these costs were accrued regardless may allow producers to realize a return on invest- of anthelmintic treatment. Because there were no ment of the original treatment given preweaning. differences in weaning weight, placement cost at While, on average, participating cooperator the time of delivery was the same for each group herds anecdotally noted returns on the added cost ($2.60/kg) based off reported market price at the of extended-release eprinomectin, variability in time of delivery by TCSCF. Records obtained market conditions over time will greatly impact through TCSCF allowed for individual animal economic outcomes for environments outside of health records including how many times a calf was the current study. Returns realized by implement- treated and the cost of health treatments through- ing a value-added practice will be highly impacted out the feeding period. Calves treated with DOR by differences in cattle prices at key marketing times preweaning had a greater number of health issues including weaning, backgrounding, or finishing. (Table 5) throughout the feedlot phase resulting in While retained ownership may increase price risk higher health costs of $6.00 per animal. due to delayed marketing and potentially added price volatility, cow–calf producers have oppor- Income. Fed cattle prices used were the average price tunities to mitigate some production risk through received by producers in this study as reported by value added practices such as preventative health TCSCF. Average final BW was used to determine the protocols that reduce performance variability live value of animals within each treatment group. (White et al., 2007). This price accounted for premiums and discounts that were paid for various quality, yield, and weight characteristics. Although quality grade distribution Table 7. Economic analysis and breakeven prices presented in Table 5 indicates a larger number of for feedlot animals treated with different anthel- carcasses grading average choice or greater for EPR- mintic treatments preweaning treated calves, premiums for YG, CAB, and prime Treatment were consistent between the two treatment groups. 2 2 $/steer DOR EPR Difference This may have been a result of variability in market- Total costs $1,375.49 $1,369.18 $6.31 ing time as market dates for finished cattle ranged Income $1,576 $1,596 $21 from 21 March 2017 to 18 July 2017. While fed cat- Profit $200.11 $227.19 $27.08 tle price was not different between treatment groups Breakeven selling price, ($/kg) ($2.87/kg), EPR calves did finish the feedlot phase For variable costs $2.43 $2.38 $0.05 with a slight weight advantage over DOR calves For all costs $2.49 $2.45 $0.04 (550 kg DOR; 557 kg EPR) resulting in a slight Treatment: DOR = doramectin (Dectomax; Zoetis Animal Health, increase in income on a live weight basis. Parsippany); EPR = eprinomectin (LongRange; Merial, Duluth, GA). Results of the feedlot budget analysis are Budget utilized from Iowa State University Extension and Outreach reported in Table 7. The culminating effect of both (Ag Decision Maker, B1-21). All market prices were average of actual healthier and heavier EPR calves resulted in a lower market values obtained through Tri-County Steer Carcass Futurity (TCSCF) records. breakeven price ($1.10 DOR vs. $1.08 EPR) and Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy115/5184427 by Ed 'DeepDyve' Gillespie user on 20 November 2018 12 Andresen et al. Beef Cattle Decision Aids. 2002. Economic Analysis of Select CONCLUSION Health and Production Management Practices. Texas To our knowledge, this is one of the two studies Cooperative Extension, Texas A&M Agrilife Extension. https://a grilife.or g/coastalbend/pr o gr am-ar eas/ published to date that evaluates the effect of extend- agricultural-economics-for-the-texas-coastal-bend/ ed-release eprinomectin on cow–calf production and budgets-and-tools/cow-calf-decision-support-aids/ feedlot performance of progeny compared to a con- financial-planning-budgets-and-investment-analysis/. ventional, short duration anthelmintic. The results Canton, J. S. and B. W. Hess. 2010. Maternal plane of nutri- of this study show no difference in cow performance tion: Impacts on fetal outcomes and postnatal offspring responses. In: B. W. Hess, T. DelCurto, J. G. P. Bowman, or reproductive success over the course of the graz- and R. C. Waterman editors. 4th Grazing Livestock ing season. Likewise, there were no improvements Nutrition Conference. Champaign (IL): West. Sect. Am. in calf preweaning performance or feedlot perfor- Soc. Anim. Sci.; p. 104–122. mance. While carcass characteristics were largely Chase, C. C., D. J. Hurley, and A. J. Reber. 2008. Neonatal unchanged due to treatment, there was an improve- immune development in the calf and its impact on vac- ment in quality grade for EPR-treated calves. cine response. Vet. Clin. North Am. Food Anim. Pract. 24:87–104. doi:10.1016/j.cvfa.2007.11.001 Improved immunocompetency via extended parasite Ciordia, H., G. V. Calvert, and H. C. McCampbell. 1982. Effect protection during the preweaning phase may have of an anthelmintic program with morantel tartrate on the had long-term impacts on feedlot morbidity result- performance of beef cattle. J. Anim. Sci. 54:1111–1114. ing in improved quality grade measurements. This doi:10.2527/jas1982.5461111x was evident by a lower percent of illness during the Clark, C. A., W. D. Busby, and P. J. Gunn. 2015. Effects of internal infection at feedlot arrival on performance and feeding phase, increased marbling score, a higher carcass characteristics of beef steers. Prof. Anim. Sci. average quality grade, and a higher percent of EPR 31:412–416. doi:10.15232/pas.2014-01381 calves grading average choice or higher, presenting Clark, C. A., P. J. Gunn, J. Dedrickson and J. Sorenson. 2013. a chance to increased returns to producers by have Comparison of ivermectin and extended-release eprinomec- more animals qualify for value-added programs. tin deworming treatment on stocker and subsequent feedlot It is important to note that FEC counts were performance and carcass characteristics of fall-born heifers. Iowa State Research Farm Progress Report. Paper 2103. very low in this study and may have provided very https://lib.dr.iastate.edu/farms_armstrong/ little opportunity for performance improvement Clark, C. A., P. J. Gunn, J. Dedrickson, and J. Sorenson. following anthelmintic treatment in both treatment 2014. Comparison of ivermectin and extended-release groups. Thus, more research is needed in popula- eprinomectin deworming treatment on stocker and sub- tions carrying greater parasitic burdens to evalu- sequent feedlot performance and carcass characteristics of fall-born Angus heifers. Paper 2103 in Iowa State ate the effect of extended-release eprinomectin on Research Farm Progress Reports. Ames, Iowa. cow–calf production. Coles, G. C., F. Jackson, W. E. Pomroy, R. K. Prichard, G. von Samson-Himmelstjerna, A. Silvestre, M. A. Conflict of interest statement. The authors Taylor, and J. Vercruysse. 2006. The detection of declare no conflict of interest. anthelmintic resistance in nematodes of veterinary importance. Vet. Parasitol. 136:167–185. doi:10.1016/j. LITERATURE CITED vetpar.2005.11.019 Fréchette, J. L., and P. Lamothe. 1981. Milk production effect Ag Decision Maker. 2017. 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Translational Animal Science – Oxford University Press
Published: Nov 15, 2018
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