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Impact of corn silage moisture at harvest on performance of growing steers with supplemental rumen undegradable protein, finishing steer performance, and nutrient digestibility by lambs

Impact of corn silage moisture at harvest on performance of growing steers with supplemental... Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Impact of corn silage moisture at harvest on performance of growing steers with supplemental rumen undegradable protein, finishing steer performance, and nutrient digestibility by lambs F. Henry Hilscher, Dirk B. Burken, Curt J. Bittner, Jana L. Gramkow, Robert G. Bondurant, Melissa L. Jolly-Breithaupt, Andrea K. Watson, Jim C. MacDonald, Terry J. Klopfenstein, and Galen E. Erickson Department of Animal Science, University of Nebraska, Lincoln, NE 68583 ABSTRACT:  Three experiments evaluated delay- to 43%, no differences (P ≥ 0.30) in dry matter intake ing corn silage harvest, silage concentration, and (DMI), ADG, G:F, or HCW were observed. In source of supplemental protein on performance and experiment 2, as DM of corn silage increased from nutrient digestibility in growing and finishing diets. 37% to 43%, ADG and G:F decreased (P ≤ 0.04). Experiment 1 used 180 crossbred yearling steers Increasing supplemental RUP in the diet increased (body weight [BW]  =  428; SD  =  39  kg) to evalu- (P ≤ 0.05) ending BW, DMI, ADG, and G:F linearly ate corn silage dry matter (DM) (37% or 43%) and as supplemental RUP increased from 0.5% to 4.2%. replacing corn with silage (15% or 45% of diet DM) In experiment 3, there were no differences (P ≥ 0.56) in finishing diets containing 40% modified distillers in DM digestibility and organic matter digestibility grains with solubles. Experiment 2 used 60 cross- between silage harvest DM and intake level. Neutral bred steers (BW = 271; SD = 32 kg) to evaluate corn detergent fiber (NDF) intake was reduced (P  < 0.01) silage harvest DM (37% or 43%) and response to for lambs fed the delayed harvest corn silage com- rumen undegradable protein (RUP) supplementa- pared to earlier corn silage harvest. As silage harvest tion (0.5%, 1.4%, 2.4%, 3.3%, or 4.2% of diet DM) in was delayed from 37% to 43% DM, NDF digesti- silage growing diets. Experiment 3 used 9 crossbred bility decreased (P < 0.01) from 64.39% to 53.41%. lambs (BW = 30.1; SD = 4.1 kg) to evaluate nutrient Although increasing corn silage concentration in digestibility of 37% or 43% DM corn silage in silage place of corn in finishing diets reduced ADG and growing diets fed ad libitum or restricted to 1.5% G:F, delayed silage harvest did not affect perfor- of BW. In experiment 1, as corn silage concentra- mance of finishing cattle. Delayed silage harvest in tion increased from 15% to 45%, average daily gain growing cattle resulted in lower ADG and G:F, pos- (ADG) and gain-to-feed ratio (G:F) decreased (P sibly due to increased starch or maturity leading to ≤ 0.04). Carcass-adjusted final BW and hot carcass decreased NDF digestibility. The addition of RUP weight (HCW) were lower (P ≤ 0.04) for steers fed to silage-based, growing diets improves performance 45% corn silage compared to 15% when fed for equal by supplying more metabolizable protein and sug- days. As DM of corn silage was increased from 37% gests RUP of corn silage is limiting. Key words: corn silage, distillers grains, dry matter, finishing cattle, growing cattle, rumen unde- gradable protein © The Author(s) 2019. 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 Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-com- mercial 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. 2019.XX:0-0 doi: 10.1093/tas/txz011 1 2 A contribution of the University of Nebraska Agricul- Corresponding author: gerickson4@unl.edu. tural Research Division supported in part by funds provided Received October 2, 2018. through the Hatch Act. Accepted February 2, 2019. 1 Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 2 Hilscher et al. INTRODUCTION have not been evaluated with distillers grains and additional RUP supplementation. Feeding corn silage allows cattle feeders to The objectives of the following studies were to take advantage of the entire corn plant at a time 1) evaluate harvest time and concentration of silage of maximum quality and tonnage as well as secure in finishing cattle diets containing distillers grains, substantial quantities of roughage and grain inven- 2) determine the effects of delaying corn silage har- tory (Burken et al., 2017b). Corn silage is a moder- vest on growing steer performance with additional ately high energy, low protein feed that allows for RUP, and 3) determine nutrient digestibility of 37% flexibility in growing and finishing cattle feeding or 43% dry matter (DM) corn silage at two intakes. programs (Allen et al., 2003). Corn silage typically contains 6.5% to 8.5% crude protein (CP), most of MATERIALS AND METHODS which is in the form of rumen degradable protein (RDP) and is used for microbial protein synthe- All animal use procedures were reviewed and sis. The NASEM (2016) lists the RUP content for approved by the University of Nebraska-Lincoln corn silage as 25.38% (% of CP). When evaluating Institutional Animal Care and Use Committee. the RUP value of forages, Kononoff et al. (2007) estimated RUP of corn silage to be 19.25% of CP, Corn Cultivation, Harvest, and Chemical but of that, intestinal RUP digestibility was only Composition 19.9%. An inadequate supply of metabolizable protein (MP) requires supplemental RUP to meet A single corn hybrid (P1498AM; Du Pont requirements (NASEM, 2016). Thus, source and Pioneer, Johnston, IA) was planted in a single irri- amount of supplemental protein are important gated field at the Eastern Nebraska Research and factors affecting growth because supplemental Extension Center (ENREC) located near Ithaca, protein provides a significant amount of the total NE in 2014. Target planting density was 84,015 dietary protein (Felix et  al., 2014). When corn seeds/ha. The field was managed in a corn and soy- silage replaces corn in finishing diets, gain-to- bean rotation every year for the previous 6 y. Corn feed ratio (G:F) decreases as corn silage increases silage was harvested using a self-propelled forage in the diet (Goodrich et  al., 1974; Burken et  al., harvester (JD 5400; John Deere, Moline, IL) set for 2017a). Management decisions, such as silage har- a 1.27-cm theoretical length of chop, without a ker- vest maturity, can affect the quality and yield of nel processing unit. corn silage and impact performance in growing Harvest DM was targeted to mimic traditional and finishing cattle (Chamberlain et  al., 1971). corn silage harvest at 37% DM or a delayed har- Hunt et  al. (1989) reported that as silage harvest vest at 43% DM. Harvest for 37% DM corn silage is delayed whole-plant yield and total digestible was harvested all on September 4, 2014, when the nutrients (TDN) in Mg/ha were increased. Allen corn was at approximately ¾ milk line and whole- et  al. (2003) summarized these changes as grain plant corn silage samples were greater than 35% development occurring largely at the expense of DM as determined by a moisture tester (Koster stover quality. The total amount of starch increases Crop Tester, Inc., Brunswick, OH) before harvest. as the plant matures (Andrae et al., 2001). Because Silage harvest for 43% DM corn silage occurred starch provides more than 50% of the energy in 2 wk later on September 16, 2014, and all occurred corn silage (Owens, 2008), this increase in starch on 1 d.  This coincided with black layer formation content represents a large increase in total energy and moisture tester samples were greater than 42% yield by harvesting corn silage with more matu- DM before harvest. Corn silage was harvested in rity. However, as corn silage is harvested later in four replications of 0.72 ha each, and within rep- the harvest season with advanced maturity, whole- lication, the total weight of silage harvested was plant neutral detergent fiber (NDF) decreases recorded for silage yield determination. In addi- as well as NDF digestibility (Andrae et  al, 2001; tion, high moisture corn (kernel DM 68%) and dry Owens, 2008). Although incorporating distillers corn (kernel DM 15%) yield strips were harvested grains and corn silage at greater concentrations within the same field on September 18, 2014 and in growing and finishing diets has been shown to November 4, 2014, respectively. Both 37% DM improve animal performance compared to corn and 43% DM silages were stored in separate side- silage alone (Felix et al., 2014; Burken et al., 2017a, by-side 3-m diameter by 61-m long plastic silos 2017b), optimum harvest time to maximize yield (AgBag, St. Nazianz, WI) and allowed to ferment and quality and the effects on animal performance for 28 d before commencing the feeding trials. Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 3 Corn silage was sampled weekly during the MI), Histophilus somnus bacterin (Zoetis Inc.), feeding trial for DM determination in a 60  °C and an injectable anthelmintic (Dectomax; Zoetis forced air oven for 48  h (Table 1). Weekly sam- Inc.). All steers were revaccinated approximately 14 ples (n  =  19) within a month were composited to 28 d after initial processing with a modified live (n  =  4) and analyzed by a commercial laboratory viral vaccine for infectious bovine rhinotracheitis, (Dairyland Laoratories, Inc., Arcadia, WI) for fer- bovine viral diarrhea types I and II, parainfluenza mentation analysis, starch, and water-soluble car- 3 virus, bovine respiratory syncytial virus (Bovi- bohydrates. Silage samples were analyzed for CP, Shield Gold 5; Zoetis Inc.), and a killed viral vac- NDF, and acid detergent fiber (ADF) by monthly cine for clostridial infections (Ultrabac 7, Zoetis composites (n  =  4) at a commercial laboratory Inc.). Before the start of the experiment, steers (Ward Laboratories, Inc., Kearney, NE). were limit-fed (Watson et al., 2013) a diet contain- Harvest data were analyzed using the ing 50% wet corn gluten feed (Sweet Bran; Cargill GLIMMIX procedure of SAS (SAS Inst. Inc., Cary, Inc., Blair, NE) and 50% alfalfa hay (DM basis) at NC). Silage harvest data were analyzed as a com- 2.0% of projected BW for 5 d to equalize gastro-in- pletely randomized design with silage strips serving testinal fill before weighing on d 0 and d 1 for initial as the experimental unit. There were 4 replications BW determination (Stock et al., 1983). Treatments per silage DM harvested, as well as 4 replications (Table 2) were designed as a 2 × 2 factorial arrange- per dry-rolled corn (DRC) and high moisture corn ment that consisted of harvested corn silage DM (HMC) yield. Significance was declared at P ≤ 0.05. (37% DM or 43% DM) and concentration of corn silage in the finishing diet (15% or 45% DM basis). Corn silage replaced HMC on a dry basis. All steers Experiment 1—Cattle Finishing Experiment were fed a supplement formulated for 33  mg/kg Crossbred yearling steers (n = 180; initial body monensin (Elanco Animal Health, Greenfield, IN) weight [BW]  =  428; SD  =  39  kg) were sorted into and a targeted intake of 90 mg/steer daily of tylosin three BW blocks and assigned randomly to 1 of 20 (Elanco Animal Health). Pens were fed once daily pens (9 steers/pen; 1 replication in heavy BW block, at approximately 0830  h. Steers were implanted 3 replications in middle BW block, and 1 replica- with 200 mg of trenbolone acetate and 20 mg estra- tion in light BW block). Before the initiation of the diol (Revalor-200; Merck Animal Health, Summit, experiment, all steers were individually identified NJ) on d 1.  Feed bunks were managed to achieve and processed at arrival at the research feedlot with: ad libitum intake, bunks were assessed at approx- a modified live viral vaccine for infectious bovine imately 0530  h with the goal of trace amounts of rhinotracheitis, bovine viral diarrhea types I  and feed at the time of feeding. All diets were fed once II, parainfluenza 3 virus, bovine respiratory syncy- daily; and feed refusals were removed from feed tial virus, Mannheimia haemolytica toxoid (Bovi- bunks when needed, weighed, and subsampled. All Shield Gold One Shot; Zoetis Inc., Kalamazoo, feed refusals were subsampled and dried for 48 h in Table 1. Nutrient and fermentation analysis of 37 and 43% DM silage (DM basis) 37% DM 43% DM a b b Item Mean C.V. Mean C.V. DM, % 37.3 3.2 42.7 3.9 CP, % of DM 7.51 3.6 7.50 1.2 NDF, % of DM 31.6 17.5 28.9 5.7 ADF, % of DM 21.4 15.8 18.6 17.9 Starch, % of DM 35.4 16.7 40.8 5.0 Sugar, % of DM 2.6 19.6 2.5 8.7 pH 3.88 1.3 3.85 1.5 Lactic acid, % of DM 3.11 26.9 4.14 28.1 Acetic acid, % of DM 3.98 21.5 2.81 27.1 Propionic acid, % of DM 0.51 26.8 0.28 54.3 Butyric acid, % of DM <0.01 0.0 <0.01 0.0 Total acids, % of DM 7.61 10.5 7.22 3.3 DM was calculated using weekly samples and oven dried for 48 h at 60 °C. All other samples are based on monthly composites (n = 4) of weekly (n = 19) samples taken during the finishing trial, and analyzed at Dairyland Laboratories (St. Cloud, MN) and Ward Laboratories (Kearney, NE). C.V. = coefficient of variation and is calculated by dividing the standard deviation by the mean and is expressed as a percentage. Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 4 Hilscher et al. Table 2. Diet composition (% DM basis) for cattle finishing experiment (experiment 1) Treatment 15% Corn silage 45% Corn silage 37% DM 43% DM 37% DM 43% DM High moisture corn 41.0 41.0 11.0 11.0 Modified distillers grains plus solubles 40.0 40.0 40.0 40.0 37% DM corn silage 15.0 — 45.0 — 43% DM corn silage — 15.0 — 45.0 Supplement 4.0 4.0 4.0 4.0 Fine ground corn 1.8048 1.8048 1.8048 1.8048 Limestone 1.7050 1.7050 1.7050 1.7050 Tallow 0.1000 0.1000 0.1000 0.1000 Salt 0.3000 0.3000 0.3000 0.3000 Trace Mineral premix 0.0500 0.0500 0.0500 0.0500 Vitamin A-D-E premix 0.0150 0.0150 0.0150 0.0150 Monensin 0.0165 0.0165 0.0165 0.0165 Tylosin 0.0087 0.0087 0.0087 0.0087 Treatments: 15% silage 37 % DM = 15% concentration of 37% DM silage, 15% silage 43% DM = 15 % concentration of 43% DM silage, 45% silage 37% DM = 45% concentration of 37% DM silage, 45% silage 43% DM = 45% concentration of 43% DM silage; all diets contained 40% MDGS. Supplement was formulated to be fed at 4% of diet DM. Trace mineral premix contained 6% Zn, 5.0% Fe, 4.0% Mn, 2.00% Cu, 0.29% Mg, 0.2% I, and 0.05% Co. Vitamin A-D-E premix contained 30,000 IU of Vitamin A, 6,000 IU of Vitamin D, 7.5 IU of Vitamin E per gram. Monensin (Rumensin-90; Elanco Animal Health, Indianapolis, IN) premix contained 198 g/kg monensin. Tylosin (Tylan-40; Elanco Animal Health, Indianapolis, IN) premix contained 88 g/kg tylosin. a 60  ºC forced-air oven for determination of DM by using pen data in the Galyean (2009) Net energy and calculation of refusal DM weight (AOAC, 1999 calculator based on NRC (1996) net energy equa- method 4.1.03). Dietary ingredients were sampled tions. The calculator uses initial BW, final BW, dry weekly for determination of DM content. Dietary matter intake (DMI), average daily gain (ADG), as-fed ingredient proportions were adjusted weekly. and a target endpoint (assuming choice quality Steers were on feed for an average of 108 d (97 d grade). block 1, 111 d block 2 and 3)  and were harvested Performance and carcass data were analyzed at a commercial abattoir (Greater Omaha Packing, using the GLIMMIX procedure of SAS (SAS Inst. Omaha, NE). On the day of shipping to the com- Inc.) with pen serving as the experimental unit mercial abattoir, pens of steers were fed 50% of the (n  =  5 per treatment) and block (n  =  3) as a fixed previous day’s DM offering at regular feeding time. effect. Data were analyzed as a randomized block Pens of steers were weighed on a platform scale design with BW sort as block. Initial BW was sig- at 1500  h before being loaded for shipping. A  4% nificantly different between silage DM treatments pencil shrink was applied to this BW for final live (1.7 kg) and included as a covariate in the model if BW and calculation of dressing percentage dressing significant. Inclusion of initial BW was not a signif- percentage, calculated as hot carcass weight (HCW) icant covariate for any variables and was removed divided by shrunk live final BW. HCW and liver from the model as a covariate. Significance of abscess scores were obtained the day of harvest. effects was determined at P ≤ 0.05. Liver abscesses were categorized as 0 (no abscesses), A–, A, or A+ (severely abscessed) according to the Experiment 2—Cattle Growing Experiment procedures outlined by Brink et  al. (1990). Liver An 83-d growing study was conducted at the abscess categories were combined to calculate the ENREC near Mead, NE using 60 crossbred steers proportion of steers with abscessed livers in each (BW = 271; SD = 32 kg). Steers were individually pen. Carcass-adjusted final BW, used in the calcula- fed using Calan gate feeders (American Calan Inc., tion of ADG and G:F, was calculated from HCW Northwood, NH). On arrival and before initiation and a 63% common dressing percentage. Marbling of the experiment, steers were identified and pro- score, 12th rib fat thickness, and longissimus mus- cessed as described previously. Cattle were limit-fed cle (LM) area were recorded after a 48  h carcass a diet of 50% Sweet Bran and 50% alfalfa hay at chill. The energy value of the diets was calculated Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 5 2.0% of projected BW for 5 d before trial initia- gluten meal. SoyPass is an enzymatically browned tion to equalize gut fill (Watson et al., 2013). Steers soybean meal and Empyreal is a concentrated corn were weighed 3 consecutive days, with the average gluten meal. Steers were stratified by day –1 and of the 3 d used as initial BW (Stock et  al., 1983). day 0 BW, and assigned randomly to 1 of 10 treat- A randomized block experimental design was used ments arranged in a 2  × 5 factorial arrangement. with treatments arranged in an unbalanced 2  × 5 Steers per level of RUP supplementation included factorial arrangement. The first factor was the base n = 8 for 0.5% RUP; n = 5 for 1.4% and 2.4 % RUP; corn silage growing diet fed at 88% of the diet DM, n  =  6 for 3.3% and 4.2% RUP treatments. With a which consisted of corn silage harvested at either limited number of bunks, a greater number of ani- 37% or 43% DM (Table 3). The second factor was mals were fed at 0.5% RUP concentration (0% RUP response to RUP supplementation at 0.5%, 1.4%, supplement, 100% RDP supplement) to better 2.4%, 3.3%, or 4.2% of the diet DM. The RUP sup- compare the response curve to RUP supplementa- plementation consisted of top dressing a blend of tion. In addition, a greater number of animals were 0/100, 25/75, 50/50, 75/25, or 100/0 combination of fed at 3.3% and 4.2% RUP concentration as it was an RDP and RUP supplement (Table 3). The sup- hypothesized the steers MP needs would be met at plement included RUP source, urea, minerals, vita- greater levels of RUP concentration. When evalu- mins A-D-E, and soybean hulls. Soybean hulls were ating response curves to increasing supplementa- the carrier that along with urea was replaced with tion of RUP, the curves are greatly influenced by the RUP sources. The supplement also included the response on either end of the curve. Therefore, monensin (Elanco Animal Health) and was formu- to ensure accuracy of estimate, steers were not lated to provide 200 mg/steer daily. The RUP sup- equally distributed across supplementation con- plement consisted of 52% SoyPass (50% CP; 75% centrations. However, blocks were balanced within RUP as % CP; Borregaard Lignotech, Rothschild, each supplementation treatment and across the two WI) and 34.7% Empyreal (75% CP; 65% RUP silage harvest treatments. The hypothesis is that a as % of CP; Cargill Inc.) and provided RUP in a nonlinear breakpoint analysis will establish the die- blend of amino acids from soybean meal and corn tary requirement for RUP supplementation, thus Table 3. Diet composition (% DM basis) for cattle growing experiment (experiment 2) Treatment 37% DM 43% Corn silage Ingredient 0.5% 1.4% 2.4% 3.3% 4.2% 0.5% 1.4% 2.4% 3.3% 4.2% 37% DM corn silage 88.0 88.0 88.0 88.0 88.0 — — — — — 43% DM corn silage — — — — — 88.0 88.0 88.0 88.0 88.0 Rumen degradable protein supplement 12.0 9.0 6.0 3.0 0.0 12.0 9.0 6.0 3.0 0.0 Rumen undegradable protein supplement 0.0 3.0 6.0 9.0 12.0 0.0 3.0 6.0 9.0 12.0 Soybean hulls 9.3552 7.1225 4.8897 2.6570 0.4242 9.3552 7.1225 4.8897 2.6570 0.4242 Limestone 0.2120 0.2583 0.3045 0.3508 0.3970 0.2120 0.2583 0.3045 0.3508 0.3970 Salt 0.4000 0.3750 0.3500 0.3250 0.3000 0.4000 0.3750 0.3500 0.3250 0.3000 Urea 1.2000 0.9750 0.7500 0.5250 0.3000 1.2000 0.9750 0.7500 0.5250 0.3000 Tallow 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 Dicalcium phosphate 0.4540 0.3905 0.3270 0.2635 0.2000 0.4540 0.3905 0.3270 0.2635 0.2000 Trace mineral premix 0.0500 0.1625 0.2750 0.3875 0.5000 0.0500 0.1625 0.2750 0.3875 0.5000 Vitamin A-D-E premix 0.0150 0.0488 0.0825 0.1163 0.1500 0.0150 0.0488 0.0825 0.1163 0.1500 Monensin 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 Bypass soy — 1.5000 3.0000 4.5000 6.0000 — 1.5000 3.0000 4.5000 6.0000 Concentrated corn gluten meal — 1.0000 2.0000 3.0000 4.0000 — 1.0000 2.0000 3.0000 4.0000 Treatments: Diets contained 88% of either 37% or 43% DM corn silage and formulated to contain 0.5%, 1.4%, 2.4%, 3.3%, or 4.2% RUP as a % of total diet. RDP and RUP supplement were formulated for a target concentration of 12%. Combinations of both were used to achieve desired RUP % of the diet DM. Trace mineral premix contained 6% Zn, 5.0% Fe, 4.0% Mn, 2.00% Cu, 0.29% Mg, 0.2% I, and 0.05% Co. Vitamin A-D-E premix contained 30,000 IU of Vitamin A, 6,000 IU of Vitamin D, 7.5 IU of Vitamin E per gram. Monensin (Rumensin-90; Elanco Animal Health, Indianapolis, IN) premix contained 198 g/kg monensin. Enzymatically browned soybean meal 50% CP; 75% RUP as % CP (SoyPass; Borregaard Lignotech, Rothschild, WI) Concentrated corn gluten meal 75% CP; 65% RUP as % of CP (Cargill Inc., Blair, NE). Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 6 Hilscher et al. increased replications were used to establish the Table 4. Diet composition (% DM basis) for lamb baseline (0.5% RUP) and the maximum response digestion experiment (experiment 3) line (3.3% and 4.2% RUP). Steers were treated for Treatment external parasites (StandGuard; Elanco Animal Ingredient 37% DM 43% Corn silage Health) and were implanted with 36  mg zeranol 37% DM corn silage 92.140 — (Ralgro; Merck) on d 1. Feed bunks were assessed 43% DM corn silage — 92.140 at approximately 0600 h and managed to allow for Bypass soy 3.000 3.000 ad libitum intake. Steers were fed ad libitum once c Concentrated corn gluten meal 2.000 2.000 daily at 0800 h. Feed refusals were collected weekly, Urea 0.750 0.750 weighed, and then dried in a 60 °C forced-air oven Limestone 0.100 0.100 for 48 h to calculate an accurate DMI for individual Trace mineral premix 2.000 2.000 Vitamin A-D-E premix 0.015 0.015 steers. Feed ingredients were sampled weekly and analyzed in the same manner for DM, with as-fed Treatments: Diets contained 92.14% of either 37% or 43% DM ingredient proportions adjusted weekly. At the con- corn silage and fed at ad libitum or restricted at 1.5% of BW. clusion of the study, steers were again limit-fed for Enzymatically browned soybean meal 50% CP; 75% RUP as % CP (SoyPass; Borregaard Lignotech, Rothschild, WI). 5 d as described earlier and weighed 3 consecutive Concentrated corn gluten meal 75% CP; 65% RUP as % of CP days to determine ending BW. The energy value of (Cargill Inc., Blair, NE). the diets was calculated by using pen data in the Trace mineral premix contained 6% Zn, 5.0% Fe, 4.0% Mn, 0.29% Galyean (2009) Net energy calculator based on Mg, 0.2% I, and 0.05% Co. NRC (1996) net energy equations. The calculator e Vitamin A-D-E premix contained 30,000 IU of Vitamin A, 6,000 uses initial BW, final BW, DMI, ADG, and target IU of Vitamin D, 7.5 IU of Vitamin E per gram. endpoint (assuming choice quality grade). Intake restriction to 1.5% of BW began on d 8 of Data were analyzed using the MIXED proce- the period 3 d before collection. BW was deter- dure of SAS (SAS Inst. Inc.) as a randomized block mined by weighing 2 consecutive days at the end design in a 2 × 5 factorial arrangement testing for of a period for subsequent restriction calculations linear and quadratic interactions between silage in the next period. During the adaptation period, DM and RUP level with steer serving as the exper- lambs were housed in individual pens with grated imental unit and weight block (n  =  5) as a fixed oors fl , individual feed bunks, and automatic water - effect. If no interactions were detected, the main ers. Feeding occurred twice daily at approximately effects of silage DM and RUP concentration were 0800 and 1500 h, and orts were collected, weighed, evaluated. To evaluate RUP level, linear and quad- and fed back during the adaptation period. ratic contrasts were developed to evaluate the effect At the end of adaptation, lambs were placed in of increasing RUP level. Significance was declared individual metabolism crates and fitted with har - at P ≤ 0.05. nesses and fecal collection bags on the evening of d 10. Total fecal output was collected twice daily Experiment 3—Lamb Digestion Experiment beginning on d 10 at 0800 and 1600 h, weighed, and An 85-d metabolism study using 9 crossbred retained individually in a cooler until the end of the wether lambs (BW  =  30.1; SD  =  4.1  kg) was con- period. Orts were collected at feeding, weighed, and ducted to determine the extent of nutrient digest- retained individually until the end of the period. At ibility in corn silage at two different levels of DM the end of each period, feces and orts were indi- and intake. Lambs were blocked into two blocks vidually composited and mixed on an as-is basis. based on BW and arranged in a 4 × 5 Latin rectan- Three 100 g subsamples were taken and dried in a gle. The metabolism study was five periods in length 60 °C forced-air oven for 48 h for orts and 72 h for with one of four treatments assigned randomly to feces. Dried samples were ground through a 1-mm lambs within each period, allowing each lamb to screen of a Wiley mill. Samples of individual feed- receive each treatment at least once. Treatments stuffs were taken on d 10 and d 14 and dried to were arranged in a 2  × 2 factorial arrangement. correct for DM of each period. Feedstuff samples Factors included corn silage harvested at either 37% were ground first through a 2-mm screen of a Wiley or 43% DM and intake of corn silage ad libitum or mill, composited by period, and a subset of period restricted to 1.5% of BW. The basel diet consisted of composites were ground through a 1-mm screen of 92% corn silage and 8% supplement (Table 4). a Wiley mill. Diet and fecal samples were analyzed The periods were 17 d in length allowing for 10 for DM, organic matter (OM), and NDF. Ground d of adaptation and 7 d for total fecal collection. feed and fecal samples were dried in a 100 °C oven Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 7 for 24 h to determine laboratory-adjusted DM and harvested. Burken et  al. (2017a) harvested corn then incinerated in a muffle furnace at 600  °C for plants at three different time points coinciding with 6 h to determine the ash content to calculate OM. traditional silage harvest with a whole-plant DM of Neutral detergent fiber was determined by refluxing 35.8%, physiological maturity with a whole-plant samples in beakers for 1 h (Van Soest and Marcus, DM of 42.4%, and corn grain harvest. In year 1 of 1964; Van Soest et al., 1991). Total tract apparent the experiment, stover yield and whole-plant yields digestibility was calculated using DM, OM, and responded in a quadratic fashion with both stover NDF disappearance. and whole-plant yields maximized at physiological Total tract digestibility data were analyzed maturity and decreased at corn grain harvest. The using the MIXED procedure of SAS (SAS Inst. authors suggested that this could be due to senes- Inc.) with period and block as fixed effects. Lamb cence and abscission as the stover portion of the was included as a random effect. Lamb served as plant became dry and brittle after physiological the experimental unit, and the model included maturity. In year 2 of the experiment, Burken et al. corn silage DM, intake, and corn silage DM by (2017a) noted linear increases in whole-plant and intake interaction. Significance was declared at stover yields as harvest was delayed from traditional P ≤ 0.05. silage harvest to corn grain harvest. Year-to-year variation will occur in corn silage yield because of RESULTS AND DISCUSSION management and environmental factors; however, Burken et al. (2017a) reported greater whole-plant yield at physiological maturity compared to tradi- Corn Silage and Grain Harvest tional corn silage harvest in both years. Filya (2004) There was an increase (P < 0.01) in yield of DM also reported DM yield in megagrams per hectare megagrams per hectare comparing 37% DM to 43% was maximized at black layer formation that coin- DM corn silage with yields of 21.41 and 22.58 Mg/ cided with 42% whole-plant DM. In addition, Hunt ha (DM), respectively (Table 5). There was no dif- et  al. (1989) reported that as harvest was delayed, ference (P = 0.64) in yield between HMC and dry whole-plant yield and TDN in megagrams per hec- corn grain with 13.72 and 13.80 Mg/ha DM yields, tare increased. These data suggest that grain yield respectively (data not presented). The increase in was maximized when delaying corn silage harvest DM yield is the result of increased grain develop- until black layer formation. In addition, high-mois- ment, as the plant matures, the grain fraction of ture corn was harvested 3 d after the 43% DM the plant is increased as more nutrients are shut- silage was harvested further suggesting grain yield tled into the corn kernels for them to fully develop. was maximized. No further yield increase for grain Suazo et  al. (1991) reported that across multiple was observed between this time point and dry grain hybrids, whole-plant DM yield in this study was harvest. maximized at black layer formation and grain yield in megagrams per hectare did not differ from black layer to corn grain harvest. Darby and Lauer (2002) Experiment 1—Cattle Finishing Experiment reported that whole-plant DM yield increased as There were no interactions between corn silage the growing season was lengthened and more grow- DM and corn silage concentration (P ≥ 0.47) for ing degree days occurred. Maximum DM yield was feedlot performance or carcass characteristics achieved when whole-plant DM reached 42% DM, (Table 6). As concentration of corn silage in the which occurred at the latest date the researchers Table 5. Delayed corn silage dry matter and yield Treatments Early harvest Late hrvest SEM P value Item Mean SD Mean SD Silage DM , % 37.3 1.2 42.7 1.7 Silage yield, DM Mg/ha 21.41 0.52 22.58 0.13 0.19 <0.01 Early harvest corn silage harvested at whole-plant DM = 37.3% DM and kernel milk = ¾ harvested on September, 4, 2014. Late harvest corn silage harvested at whole-plant DM = 42.7% DM and kernel black layer formation harvested on September 16, 2014. DM was calculated using weekly (n = 19) samples and oven dried for 48 h at 60 °C. Coefficient of variation was 3.2 for early harvest and 3.9 for late harvest based on weekly DM samples. Silage yield = total DM Mg/ha at 100% DM. Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 8 Hilscher et al. Table 6. The effects of delayed corn silage harvest and increased concentrations of corn silage on feedlot performance and carcass characteristics of cross bred yearling steers (experiment 1) Treatments 15% Corn silage 45% Corn silage P value b c d Variable 37% DM 43% DM 37% DM 43% DM sem Int. Concentration DM Feedlot performance Initial BW, kg 426 427 426 427 0.5 0.77 0.87 <0.01 Final BW , kg 621 626 608 608 7.0 0.71 0.04 0.68 Live final BW, kg 638 649 635 640 9.7 0.76 0.54 0.44 DMI, kg/d 13.0 13.2 13.3 13.5 0.2 0.82 0.15 0.30 ADG, kg 1.85 1.87 1.72 1.71 0.07 0.79 0.04 0.90 G:F 0.142 0.142 0.129 0.126 0.003 0.79 <0.01 0.64 NE , Mcal/kg DM 1.81 1.80 1.68 1.66 0.03 0.88 <0.01 0.62 NE , Mcal/kg DM 1.17 1.16 1.06 1.04 0.02 0.83 <0.01 0.53 Carcass characteristics Hot carcass weight, kg 391 394 383 383 4.4 0.71 0.04 0.68 Dressing percentage, % 61.1 60.8 60.2 59.8 0.56 0.93 0.05 0.68 Longissimus area, cm 84.38 82.63 84.78 83.36 0.89 0.85 0.52 0.08 12th-rib fat, cm 1.28 1.40 1.26 1.28 0.08 0.47 0.26 0.27 Marbling score 514 498 489 493 14.0 0.48 0.29 0.67 Treatments: 15% silage 37% DM = 15% concentration of 37% DM silage, 15% silage 43% DM = 15% concentration of 43% DM silage, 45% silage 37% DM = 45 % concentration of 37% DM silage, 45% silage 43% DM = 45 % concentration of 43% DM silage; all diets contained 40% MDGS. Silage concentration × silage DM interaction. Fixed effect of silage concentration. Fixed effect of silage DM. Final BW, were calculated based on HCW/common dressing percent of 63%. NE and NE were calculated using methodology of NRC (1996) using a tool developed by Galyean (2009) assuming a 625 kg target endpoint. m g Marbling score 400 = small00, 500 = modest00. finishing diet increased from 15% to 45%, ADG As corn silage concentration increased from 15% decreased (P  =  0.04) whereas DMI did not differ to 45%, DMI, ADG, and G:F decreased linearly, (P = 0.15), and this, in turn, led to a decrease in but when comparing diets with 45% corn silage, the G:F (P < 0.01). Goodrich et al. (1974) reported lin- diet with 40% MDGS had greater ADG and G:F ear decreases in ADG and G:F as corn silage was compared to 45% silage with 0% MDGS. Although increased in the finishing diet. Similarly, Gill et al. performance was reduced when feeding greater (1976) observed decreased G:F as corn silage was concentrations of corn silage and distillers grains increased in the finishing diet. Brennan et al. (1987) plus solubles (DGS), the decrease in performance is reported no difference in DMI, ADG, or G:F less with DGS in the diet compared to in previous between cattle fed 41% and 23% corn silage in fin- studies without DGS. ishing diets. Erickson (2001) evaluated corn silage in Calculated net energy for maintenance (NE ) finishing diets at 15%, 30%, or 45% of diet on a DM and net energy for gain (NE ) values were decreased basis. In two trials with yearling cattle, DMI was not (P  <  0.01) as corn silage concentration increased affected by treatment, but ADG and G:F decreased from 15% to 45% of the diet DM. Preston (1975) as corn silage concentration increased from 15% to summarized experiments where corn silage replaced 45% of the diet. In a trial with calf feds, Erickson corn grain up to 64% of the diet and reported linear (2001) reported that DMI increased as corn silage decreases in NE and NE values as concentration m g concentration increased; however, ADG and G:F of corn silage increased. Similarly, Burken et  al. both linearly decreased with increased corn silage. (2017a) reported linear decreases in NE by 4% At present, Burken et al. (2017a) fed increased con- (2.00 to 1.92) and NE by 4.5% (1.34 to 1.28) values centrations of corn silage at 15%, 30%, 45%, and as corn silage concentration increased from 15% to 55% with modified distillers grains plus solubles 55% of the diet DM. Although performance was (MDGS) concentration of 40% (DM basis) and an reduced when feeding high levels of corn silage and additional diet of 45% corn silage and no distillers DGS, the decrease in performance is less with DGS in finishing diets to evaluate animal performance. in the diet compared to previous studies without Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 9 DGS. Burken et  al. (2017a) fed 40% MDGS in increase in DMI. There was no difference in ADG the diet and increased the amount of corn silage between steers fed 28% and 42% DM silage; how- in the diet from 15% to 45%, which resulted in a ever, there was a numerical increase in ADG and 5% reduction in G:F. However, without DGS in G:F for steers fed 42% DM silage. Browne et  al. the diet, both Goodrich et al. (1974) and Erickson (2004) compared silages harvested at 29.1%, 33.9%, (2001) reported a 15% reduction in G:F when and 39.3% whole-plant DM in European style fin- increasing silage concentration from 15% to 45%. ishing systems with 89% corn silage included in the As corn silage concentration increased from 15% to finishing diet. The authors found that as harvest 45%, ADG and G:F decreased due to the decrease was delayed, DMI increased and G:F decreased; in dietary energy content as corn silage is lower in however, final BW, HCW, and ADG were not differ - net energy compared to the corn gain it replaced in ent. These data tend to support a lack of difference the finishing diet. in finishing diets with 15% to 45% silage, or rela- Carcass-adjusted final BW and HCW were tively low inclusions when corn silage is harvested reduced (P ≤ 0.04) for steers fed 45% corn silage between 25% and 44% DM. It is unclear if the lack compared to 15%. Burken et al. (2017a) reported a of differences due to harvest DM is due to low linear decrease in final BW and HCW as corn silage inclusions and masking any difference in silage or was increased in finishing diets. In two additional if just no difference exists between harvest DM of studies by Burken et al. (2017b), they reported that silage when fed in finishing diets. Similar to ADG final BW and HCW tended to decrease in the first and G:F in this study, no differences (P ≥ 0.27) in experiment and significantly decreased in final BW dressing percent, 12th rib fat, or marbling scores and HCW in the second experiment as concentra- were observed as DM of corn silage was increased. tion of corn silage increased from 15% to 45% of In finishing diets, increasing silage inclusion the diet. Dressing percentage decreased (P  =  0.05) from 15% to 45% of diet DM decreases ADG as concentration of corn silage was increased from and G:F that agrees with previous work, but the 15% to 45% in the finishing diet. When cattle are decreases are less than some previous studies, par- fed elevated concentrations of corn silage, dress- ticularly those without distillers grains. Whether ing percentage decreases due to increased gut fill. silage was harvested at a DM of 37% or 43% DM Peterson et  al. (1973) reported that as corn silage did not affect ADG or G:F in finishing cattle. concentration increased, dressing percentage lin- early decreased. Similarly, Brennan et  al. (1987) Experiment 2—Cattle Growing Experiment reported cattle fed increased concentrations of corn There were no linear (P ≥ 0.33) or quadratic (P silage had decreased dressing percentages. Burken ≥ 0.36) interactions between corn silage DM and et al. (2017a) reported a linear decrease in dressing level of RUP supplementation for growing perfor- percentage as corn silage concentration increased. mance. As DM of corn silage increased from 37% There were no differences (P ≥ 0.31) in LM area, to 43%, there was a significant decrease (P = 0.04) 12th rib fat, and marbling score as concentration in ending BW (Table 7). There was no difference of corn silage concentration increased. Burken (P = 0.93) in DMI between 37% and 43% DM corn et al. (2017b) also reported no differences in carcass silage, and ADG was reduced (P = 0.01) as DM of characteristics when silage was fed at 15% or 45% silage increased, which led to a significant decrease of the diet. (P < 0.01) in G:F. Worley et al. (1986) fed silage har- As DM of corn silage increased from 37% to vested at 31% or 44% whole-plant DM to growing 43% due to delaying harvest, there were no differ- heifers. The authors reported decreased ADG and ences (P ≥ 0.30) in DMI, ADG, or G:F. In addition, G:F in the first 28 DOF when feeding drier silage, there were no differences (P = 0.68) in carcass-ad- similar to this study. Although overall performance justed final BW or HCW as corn silage DM was from d 0 to d 70 was not statistically different, the increased. Chamberlain et  al. (1971) compared 44% DM silage had numerically lower ADG and corn silage in finishing diets (27% of diet DM) G:F. Chamberlain et  al. (1971) compared corn harvested from 25% to 44% whole-plant DM, and silage in growing diets (70% of diet DM) harvested as harvest maturity increased, there were no dif- from 25% to 44% whole-plant DM. There were no ferences in final BW, DMI, ADG, or G:F in the differences in ADG between the first three stages finishing period across all corn silages. Buchanan- of maturity harvested at 25%, 30%, and 36.5% Smith (1982) compared corn silage harvested at DM, but the latest maturity harvested at 44% DM 28% or 42% whole-plant DM in finishing steers and had the lowest ADG. Intake was lowest for latest reported that steers fed 42% DM silage had a 5% Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 10 Hilscher et al. harvested corn silage and G:F decreased as harvest (Table 8). There was a linear increase (P = 0.05) in was delayed. When evaluating corn silage harvested DMI as RUP concentration increased in the grow- at ½ milk line (28.4% DM) or black layer (42.5% ing diet. Daily gain improved as RUP concentration DM), Andrae et  al. (2001) reported decreases in increased in the growing diet, with ADG increasing total tract starch, NDF digestibility (NDFD), and (P < 0.01) linearly from 0.5% to 4.2% RUP concen- ADF digestibility (ADFD) by 6.5, 5.9, and 7.5 per- tration. With a greater increase in ADG compared centage units, respectively. The authors concluded to the increase in DMI, G:F increased (P  <  0.01) that NDFD and ADFD decreased due to increased linearly as RUP concentration increased. Steers fed lignification, and also the increased starch content the 4.2% supplemental RUP treatment were 19.9%, from the more mature corn silage caused an unfa- 14.5%, 5.9%, and 2.7% more efficient than steers vorable rumen environment with lower pH that supplemented with 0.5%, 1.4%, 2.4%, or 3.3% RUP, hindered fiber digestion. Calculated NE and NE respectively. m g values were significantly lower (P = 0.03) for 43% Ingredients can vary in RUP content as well DM compared to 37% DM corn silage. These stud- as RUP digestibility. Corn grain is the most com- ies suggest some consensus that dryer silage fed to monly fed grain in the United States, and dry corn growing steers reduces ADG and G:F and is likely grain has a RUP value of approximately 65.3% due to either decreases in fiber digestion due to (NASEM, 2016). Corn processing method impacts more mature plants or more starch concentration RUP %. Work by Benton et al. (2005) showed that that decreases fiber digestion in the rumen. when grain is harvested as HMC, the RUP content As supplemental RUP in the growing diet of corn grain decreases, and it becomes more rumen increased from 0.5% to 4.2% of total diet, end- degradable as the moisture content and length of ing BW increased linearly (P  <  0.01) with steers ensiling period increases. The corn grain in silage receiving 4.2% RUP as a % of total diet having is harvested earlier than HMC and wetter, suggest- the heaviest ending BW and steers receiving 0.5% ing a further increase in RDP content of the corn supplemental RUP having the lowest ending BW grain in corn silage. The NASEM (2016) lists the Table 7. Effects of delayed corn silage harvest on growing steer performance (experiment 2) Treatments Item 37% DM 43% DM SEM P value Initial BW, kg 271 271 1.8 0.92 Ending BW, kg 384 375 3.0 0.04 DMI, kg/d 8.2 8.1 0.1 0.93 ADG, kg 1.45 1.33 0.03 0.01 G:F 0.177 0.164 0.001 <0.01 NE , Mcal/kg DM 1.73 1.65 0.02 <0.01 NE , Mcal/kg DM 1.11 1.04 0.02 <0.01 Treatments: steers were fed 88% of either 37% or 43% DM corn silage. NE and NE were calculated using methodology of NRC (1996) using a tool developed by Galyean (2009) assuming a 625 kg target endpoint. m g Table 8. The effects of increased concentration of RUP in silage based growing diets on performance of cross bred steers (experiment 2) Treatments Variable 0.5% 1.4% 2.4% 3.3% 4.2% SEM Lin. Quad. Initial BW, kg 270 271 271 270 272 2.4 0.98 0.60 Ending BW, kg 359 374 388 382 394 4.1 <0.01 0.88 DMI, kg/d 7.7 8.3 8.6 7.9 8.3 0.2 0.05 0.84 ADG, kg 1.14 1.32 1.50 1.43 1.56 0.04 <0.01 0.82 G:F 0.149 0.159 0.175 0.181 0.186 0.002 <0.01 0.57 NE , Mcal/kg DM 1.58 1.63 1.71 1.77 1.79 0.04 <0.01 0.57 NE , Mcal/kg DM 0.97 1.02 1.09 1.14 1.16 0.03 <0.01 0.57 Treatments: Diets contained 88% of either 37% or 43% DM corn silage and formulated to contain 0.5%, 1.4%, 2.4%, 3.3%, or 4.2% RUP % of total diet. NE and NE were calculated using methodology of NRC (1996) using a tool developed by Galyean (2009) assuming a 625 kg target endpoint. m g Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 11 RUP content for corn silage as 25.38% (% of CP). was different. The DDGS and SBM supplemented When evaluating the RUP value of forages, work treatments had greater final BW, DMI, ADG, and by Kononoff et  al. (2007) found that the digesti- G:F. As corn silage is lacking in the protein neces- bility of forage RUP is much lower than the 80% sary to meet MP requirements in growing calves, suggested by the NRC (1996). Specifically looking supplementing with protein such as DDGS or SBM at corn silage, Kononoff et  al. (2007) estimated that has more RUP than urea benefited these grow- RUP (% of CP) to be 19.25%, but with an intesti- ing calves compared to increased RDP in the urea nal RUP digestibility of only 19.9%. Much of the treatment. All these studies, along with results from protein in silage is fermented to soluble protein in experiment 2, suggest the MP requirement is larger the bunker and to ammonia in the rumen. Such than previously thought or corn silage is provid- degradation reduces the amount of intact pro- ing less digestible RUP than previously thought. tein and amino acids available in the small intes- More research is needed on RUP concentration tine as RUP (Owens et  al., 2018). The level and and digestibility to accurately model MP supply degradability in the rumen of protein can have a compared to requirements for the growing calves in large impact on growing steer performance. Byers experiment 2. and Moxon (1980) fed corn silage-based growing diets (55% of diet DM) and three levels of pro- Experiment 3—Lamb Digestion Experiment tein, 11.6%, 14.1%, or 16.5%, to growing steers There was no interaction between corn silage (average initial BW  =  233  kg). The additional CP DM and intake level for DM and OM intake and in these supplements came from increased soybean digestibility, and the main effects will be presented. meal (44% RUP; NASEM, 2016) and linseed meal Owing to intake restriction between ad libitum and (32% RUP; NASEM, 2016). As CP increased from lambs held at 1.5% of BW, there was a significant 11.6 to 16.5, DMI, ADG, and G:F significantly (P  <  0.01) decrease in DMI and OM intake for increased. This indicated that calves fed 11.6% CP restricted lambs as designed (Table 9). There were were not meeting their MP requirements, therefore no differences (P  =  0.56) in DM digestibility and limiting growth. Perry et al. (1983) fed corn silage OM digestibility between silage harvest and intake (92% of diet DM) to growing steers (average ini- level. Worley et  al. (1986) fed silage harvested at tial BW = 213 kg) with supplemental soybean meal 31% or 44% whole-plant DM either ad libitum or to achieve CP levels of 9%, 11%, or 13% of DM. restricted to growing lambs. The authors reported Increasing the level of CP in the diet increased greater DMI for 44% DM corn silage when fed ad DMI, ADG, and G:F of these growing calves. libitum, but there were no differences in DM digest- Although Byers and Moxon (1980) and Perry et al. ibility between silage DM when fed ad libitum or (1983) concluded that increased dietary protein in restricted. Johnson and McClure (1968) reported silage based growing diets improves performance, it greater DMI as whole-plant DM increased to is actually RUP of supplemental CP that had a sig- 33.9% DM and remained constant up to 46% nificant impact on performance because the addi- when fed to growing lambs. The authors reported tion of urea (100% RDP) does not have the same DM digestibility and OM digestibility were signif- magnitude of increase as the RUP supplements that icantly affected by harvest DM over a broad range were used in those trials. Felix et  al. (2014) com- of harvest DM. Between 33.9% and 42.6% DM, pared corn silage-based (90% of DM) diets with DM digestibility changes were minimal: 68.2% vs. increased levels of CP at 11%, 12%, and 13%, and 68.9% for 33.9 and 42.6% DM silages, respectively. only urea was used to increase CP. When increasing When feeding beef steers, Joanning et  al. (1981) the CP through increased urea in silage diets fed to reported no difference in DM digestibility between growing calves (initial BW  =  198  kg), the authors corn silage harvested at 22% or 35% DM. Similarly, reported a linear decrease in ending BW, ADG, and McGeough et al. (2010) reported no differences in G:F and increasing the amount of RDP did not DMI or DM digestibility between silage harvested increase the microbial crude protein supply enough at four different maturities. to maximize growth. Felix et  al. (2014) compared There was an intake × harvest time interaction silage-based (79% on DM basis) growing diets with for NDF intake and therefore the simple effects will sources of supplemental protein on animal perfor- be discussed. Concentration of NDF was lower in mance. The authors compared silage growing diets 43% DM silage so lambs restricted to 1.5% BW for and formulated diets to be iso-nitrogenous with a intake had lower NDF intake than 37% DM. The CP of 10.8%; however, the source of supplemen- interaction was observed because the magnitude of tal protein, urea, DDGS, or soybean meal (SBM), Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 12 Hilscher et al. Table 9. Effect of delayed corn silage harvest and intake restriction on digestibility in lambs (experiment 3) Treatments Ad libitum Limited P value b c d Item 37% DM 43% DM 37% DM 43% DM SEM Int. Intake DM DM Intake, kg/d 2.14 1.99 1.16 1.15 0.08 0.28 <0.01 0.23 Digestibility, % 70.8 71.5 71.9 71.1 1.3 0.56 0.76 0.97 OM Intake, kg/d 2.01 1.89 1.09 1.09 0.08 0.33 <0.01 0.39 Digestibility, % 72.6 73.3 73.7 73.1 1.3 0.56 0.67 0.99 NDF Intake, kg/d 1.07 0.77 0.58 0.45 0.03 <0.01 <0.01 <0.01 Digestibility, % 63.4 53.3 65.4 53.5 0.02 0.67 0.60 <0.01 Treatments: Diets contained 92.14% of either 37% or 43% DM corn silage and fed at ad libitum or restricted at 1.5% of BW. Silage intake × silage DM interaction. Fixed effect of silage intake. Fixed effect of silage DM. difference in NDF intake was even greater when delayed in growing lambs (Johnson and McClure, lambs were fed ad libitum, which was due to lower 1968). Joanning et al. (1981) reported that as silage NDF concentration and numerically lower DMI DM increased from 22% to 35% DM, there was a for 43% DM silage compared to 37% DM silage. decrease in NDFD of 14.6 percentage units in a 90% In general, intake of NDF was reduced (P < 0.01) silage diet. Jensen et  al. (2005) reported decreased when intake was restricted as expected but also NDFD as harvest DM increased from 35% to 40% reduced (P  <  0.01) for lambs fed 43% DM corn DM. Similar to decreased NDF digestion by lambs silage compared to 37% DM corn silage. The NDF in experiment 3, all studies show decreased fiber concentration of the silage was decreased and starch digestibility as silage harvest is delayed (i.e., DM concentration increased as corn silage harvest was increased in silage). Delaying silage harvest allows delayed. As silage harvest was delayed from 37% to for increased grain yield as a percentage of whole- 43% DM, there was a significant decrease (P < 0.01) plant yield, with no impact on OM digestion, but in NDFD from 64.39% to 53.41%. Worley et  al. delaying silage harvest decreases NDF content in (1986) reported greater NDF intake in 44% DM this study and many others. corn silage compared to 31% DM but reported no Delaying corn silage harvest increased corn difference in NDFD when lambs were fed ab libi- silage yield and maximized grain yield. Although tum or had intake restricted. The corn silage used increasing corn silage concentration from 15% to by Worley et al. (1986) increased in NDF concen- 45% in place of corn in finishing diets reduced ADG tration as corn silage harvest was delayed, this is and G:F, there were no differences in performance not in agreement with previous work that shows when corn silage harvest was delayed from 37% to NDF concentration decreases as corn silage har- 43% DM in these finishing diets. However, delayed vest is delayed, and could explain why these authors corn silage harvest in growing diets indicates that reported increased NDF intake. Jensen et al. (2005) 37% DM silage would result in greater ADG and reported NDF intake decreased as whole-plant DM G:F compared to feeding 43% corn silage. As corn increased from 35% to 40% DM. As corn silage is silage harvest is delayed, plant NDF decreases at harvested later in the harvest season with advanced the expense of corn grain being maximized and maturity, whole-plant NDF decreases (Bal et  al., NDF intake and digestibility decrease. Increasing 1997; Di Marco et al., 2002; Ferraretto and Shaver, the amount of RUP in silage growing diets resulted 2012). Andrae et  al. (2001) reported that as the in linear increases in DMI, ADG, and G:F. These corn plant matures, the NDF content of the corn results indicate that the addition of RUP into silage plant decreased from 43.67% to 38.43% NDF growing diets will improve performance by supply- when harvested at 28.4% and 42.4% DM, respec- ing more MP. tively. These authors also reported digestibility of Although increasing the concentration of corn the NDF decreased from 39.11% to 33.21% when silage in the finishing diet resulted in decreased per - corn silage harvest was delayed. Fiber digestibility formance compared to lower concentrations, the significantly decreased as corn silage harvest was potential for increasing net farm income may be Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 13 Byers,  F.M., and A.L.  Moxon. 1980. Protein and selenium increased. Economic analysis was not performed, levels for growing and finishing beef cattle. J. Anim. Sci. but by reducing cost of gain during the finishing 50:1136–1144. doi:10.2527/jas1980.5061136x. period and recycling of nutrients from feedlot Chamberlain, C.C., H.A. Fribourg, K.M. Barth, J.H. Felts, and manure to farm fields, an opportunity may exist to J.M. Anderson. 1971. Effect of maturity of corn silage at increase farm profits. harvest on the performance of feeder heifers. J. Anim. Sci. 33:161–166. doi:10.2527/jas1971.331161x. 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The effects of corn silage dry mat- rations containing varying proportions of com grain ter content and sodium bicarbonate addition on nutrient and com silage. J. Anim. Sci. 41:622–624. doi:10.2527/ digestion and growth by lambs and calves. J. Anim. Sci. jas1975.412622x. 63:1728–1736. doi:10.2527/jas1986.6361728x. Translate basic science to industry innovation http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Translational Animal Science Oxford University Press

Impact of corn silage moisture at harvest on performance of growing steers with supplemental rumen undegradable protein, finishing steer performance, and nutrient digestibility by lambs

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Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Impact of corn silage moisture at harvest on performance of growing steers with supplemental rumen undegradable protein, finishing steer performance, and nutrient digestibility by lambs F. Henry Hilscher, Dirk B. Burken, Curt J. Bittner, Jana L. Gramkow, Robert G. Bondurant, Melissa L. Jolly-Breithaupt, Andrea K. Watson, Jim C. MacDonald, Terry J. Klopfenstein, and Galen E. Erickson Department of Animal Science, University of Nebraska, Lincoln, NE 68583 ABSTRACT:  Three experiments evaluated delay- to 43%, no differences (P ≥ 0.30) in dry matter intake ing corn silage harvest, silage concentration, and (DMI), ADG, G:F, or HCW were observed. In source of supplemental protein on performance and experiment 2, as DM of corn silage increased from nutrient digestibility in growing and finishing diets. 37% to 43%, ADG and G:F decreased (P ≤ 0.04). Experiment 1 used 180 crossbred yearling steers Increasing supplemental RUP in the diet increased (body weight [BW]  =  428; SD  =  39  kg) to evalu- (P ≤ 0.05) ending BW, DMI, ADG, and G:F linearly ate corn silage dry matter (DM) (37% or 43%) and as supplemental RUP increased from 0.5% to 4.2%. replacing corn with silage (15% or 45% of diet DM) In experiment 3, there were no differences (P ≥ 0.56) in finishing diets containing 40% modified distillers in DM digestibility and organic matter digestibility grains with solubles. Experiment 2 used 60 cross- between silage harvest DM and intake level. Neutral bred steers (BW = 271; SD = 32 kg) to evaluate corn detergent fiber (NDF) intake was reduced (P  < 0.01) silage harvest DM (37% or 43%) and response to for lambs fed the delayed harvest corn silage com- rumen undegradable protein (RUP) supplementa- pared to earlier corn silage harvest. As silage harvest tion (0.5%, 1.4%, 2.4%, 3.3%, or 4.2% of diet DM) in was delayed from 37% to 43% DM, NDF digesti- silage growing diets. Experiment 3 used 9 crossbred bility decreased (P < 0.01) from 64.39% to 53.41%. lambs (BW = 30.1; SD = 4.1 kg) to evaluate nutrient Although increasing corn silage concentration in digestibility of 37% or 43% DM corn silage in silage place of corn in finishing diets reduced ADG and growing diets fed ad libitum or restricted to 1.5% G:F, delayed silage harvest did not affect perfor- of BW. In experiment 1, as corn silage concentra- mance of finishing cattle. Delayed silage harvest in tion increased from 15% to 45%, average daily gain growing cattle resulted in lower ADG and G:F, pos- (ADG) and gain-to-feed ratio (G:F) decreased (P sibly due to increased starch or maturity leading to ≤ 0.04). Carcass-adjusted final BW and hot carcass decreased NDF digestibility. The addition of RUP weight (HCW) were lower (P ≤ 0.04) for steers fed to silage-based, growing diets improves performance 45% corn silage compared to 15% when fed for equal by supplying more metabolizable protein and sug- days. As DM of corn silage was increased from 37% gests RUP of corn silage is limiting. Key words: corn silage, distillers grains, dry matter, finishing cattle, growing cattle, rumen unde- gradable protein © The Author(s) 2019. 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 Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-com- mercial 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. 2019.XX:0-0 doi: 10.1093/tas/txz011 1 2 A contribution of the University of Nebraska Agricul- Corresponding author: gerickson4@unl.edu. tural Research Division supported in part by funds provided Received October 2, 2018. through the Hatch Act. Accepted February 2, 2019. 1 Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 2 Hilscher et al. INTRODUCTION have not been evaluated with distillers grains and additional RUP supplementation. Feeding corn silage allows cattle feeders to The objectives of the following studies were to take advantage of the entire corn plant at a time 1) evaluate harvest time and concentration of silage of maximum quality and tonnage as well as secure in finishing cattle diets containing distillers grains, substantial quantities of roughage and grain inven- 2) determine the effects of delaying corn silage har- tory (Burken et al., 2017b). Corn silage is a moder- vest on growing steer performance with additional ately high energy, low protein feed that allows for RUP, and 3) determine nutrient digestibility of 37% flexibility in growing and finishing cattle feeding or 43% dry matter (DM) corn silage at two intakes. programs (Allen et al., 2003). Corn silage typically contains 6.5% to 8.5% crude protein (CP), most of MATERIALS AND METHODS which is in the form of rumen degradable protein (RDP) and is used for microbial protein synthe- All animal use procedures were reviewed and sis. The NASEM (2016) lists the RUP content for approved by the University of Nebraska-Lincoln corn silage as 25.38% (% of CP). When evaluating Institutional Animal Care and Use Committee. the RUP value of forages, Kononoff et al. (2007) estimated RUP of corn silage to be 19.25% of CP, Corn Cultivation, Harvest, and Chemical but of that, intestinal RUP digestibility was only Composition 19.9%. An inadequate supply of metabolizable protein (MP) requires supplemental RUP to meet A single corn hybrid (P1498AM; Du Pont requirements (NASEM, 2016). Thus, source and Pioneer, Johnston, IA) was planted in a single irri- amount of supplemental protein are important gated field at the Eastern Nebraska Research and factors affecting growth because supplemental Extension Center (ENREC) located near Ithaca, protein provides a significant amount of the total NE in 2014. Target planting density was 84,015 dietary protein (Felix et  al., 2014). When corn seeds/ha. The field was managed in a corn and soy- silage replaces corn in finishing diets, gain-to- bean rotation every year for the previous 6 y. Corn feed ratio (G:F) decreases as corn silage increases silage was harvested using a self-propelled forage in the diet (Goodrich et  al., 1974; Burken et  al., harvester (JD 5400; John Deere, Moline, IL) set for 2017a). Management decisions, such as silage har- a 1.27-cm theoretical length of chop, without a ker- vest maturity, can affect the quality and yield of nel processing unit. corn silage and impact performance in growing Harvest DM was targeted to mimic traditional and finishing cattle (Chamberlain et  al., 1971). corn silage harvest at 37% DM or a delayed har- Hunt et  al. (1989) reported that as silage harvest vest at 43% DM. Harvest for 37% DM corn silage is delayed whole-plant yield and total digestible was harvested all on September 4, 2014, when the nutrients (TDN) in Mg/ha were increased. Allen corn was at approximately ¾ milk line and whole- et  al. (2003) summarized these changes as grain plant corn silage samples were greater than 35% development occurring largely at the expense of DM as determined by a moisture tester (Koster stover quality. The total amount of starch increases Crop Tester, Inc., Brunswick, OH) before harvest. as the plant matures (Andrae et al., 2001). Because Silage harvest for 43% DM corn silage occurred starch provides more than 50% of the energy in 2 wk later on September 16, 2014, and all occurred corn silage (Owens, 2008), this increase in starch on 1 d.  This coincided with black layer formation content represents a large increase in total energy and moisture tester samples were greater than 42% yield by harvesting corn silage with more matu- DM before harvest. Corn silage was harvested in rity. However, as corn silage is harvested later in four replications of 0.72 ha each, and within rep- the harvest season with advanced maturity, whole- lication, the total weight of silage harvested was plant neutral detergent fiber (NDF) decreases recorded for silage yield determination. In addi- as well as NDF digestibility (Andrae et  al, 2001; tion, high moisture corn (kernel DM 68%) and dry Owens, 2008). Although incorporating distillers corn (kernel DM 15%) yield strips were harvested grains and corn silage at greater concentrations within the same field on September 18, 2014 and in growing and finishing diets has been shown to November 4, 2014, respectively. Both 37% DM improve animal performance compared to corn and 43% DM silages were stored in separate side- silage alone (Felix et al., 2014; Burken et al., 2017a, by-side 3-m diameter by 61-m long plastic silos 2017b), optimum harvest time to maximize yield (AgBag, St. Nazianz, WI) and allowed to ferment and quality and the effects on animal performance for 28 d before commencing the feeding trials. Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 3 Corn silage was sampled weekly during the MI), Histophilus somnus bacterin (Zoetis Inc.), feeding trial for DM determination in a 60  °C and an injectable anthelmintic (Dectomax; Zoetis forced air oven for 48  h (Table 1). Weekly sam- Inc.). All steers were revaccinated approximately 14 ples (n  =  19) within a month were composited to 28 d after initial processing with a modified live (n  =  4) and analyzed by a commercial laboratory viral vaccine for infectious bovine rhinotracheitis, (Dairyland Laoratories, Inc., Arcadia, WI) for fer- bovine viral diarrhea types I and II, parainfluenza mentation analysis, starch, and water-soluble car- 3 virus, bovine respiratory syncytial virus (Bovi- bohydrates. Silage samples were analyzed for CP, Shield Gold 5; Zoetis Inc.), and a killed viral vac- NDF, and acid detergent fiber (ADF) by monthly cine for clostridial infections (Ultrabac 7, Zoetis composites (n  =  4) at a commercial laboratory Inc.). Before the start of the experiment, steers (Ward Laboratories, Inc., Kearney, NE). were limit-fed (Watson et al., 2013) a diet contain- Harvest data were analyzed using the ing 50% wet corn gluten feed (Sweet Bran; Cargill GLIMMIX procedure of SAS (SAS Inst. Inc., Cary, Inc., Blair, NE) and 50% alfalfa hay (DM basis) at NC). Silage harvest data were analyzed as a com- 2.0% of projected BW for 5 d to equalize gastro-in- pletely randomized design with silage strips serving testinal fill before weighing on d 0 and d 1 for initial as the experimental unit. There were 4 replications BW determination (Stock et al., 1983). Treatments per silage DM harvested, as well as 4 replications (Table 2) were designed as a 2 × 2 factorial arrange- per dry-rolled corn (DRC) and high moisture corn ment that consisted of harvested corn silage DM (HMC) yield. Significance was declared at P ≤ 0.05. (37% DM or 43% DM) and concentration of corn silage in the finishing diet (15% or 45% DM basis). Corn silage replaced HMC on a dry basis. All steers Experiment 1—Cattle Finishing Experiment were fed a supplement formulated for 33  mg/kg Crossbred yearling steers (n = 180; initial body monensin (Elanco Animal Health, Greenfield, IN) weight [BW]  =  428; SD  =  39  kg) were sorted into and a targeted intake of 90 mg/steer daily of tylosin three BW blocks and assigned randomly to 1 of 20 (Elanco Animal Health). Pens were fed once daily pens (9 steers/pen; 1 replication in heavy BW block, at approximately 0830  h. Steers were implanted 3 replications in middle BW block, and 1 replica- with 200 mg of trenbolone acetate and 20 mg estra- tion in light BW block). Before the initiation of the diol (Revalor-200; Merck Animal Health, Summit, experiment, all steers were individually identified NJ) on d 1.  Feed bunks were managed to achieve and processed at arrival at the research feedlot with: ad libitum intake, bunks were assessed at approx- a modified live viral vaccine for infectious bovine imately 0530  h with the goal of trace amounts of rhinotracheitis, bovine viral diarrhea types I  and feed at the time of feeding. All diets were fed once II, parainfluenza 3 virus, bovine respiratory syncy- daily; and feed refusals were removed from feed tial virus, Mannheimia haemolytica toxoid (Bovi- bunks when needed, weighed, and subsampled. All Shield Gold One Shot; Zoetis Inc., Kalamazoo, feed refusals were subsampled and dried for 48 h in Table 1. Nutrient and fermentation analysis of 37 and 43% DM silage (DM basis) 37% DM 43% DM a b b Item Mean C.V. Mean C.V. DM, % 37.3 3.2 42.7 3.9 CP, % of DM 7.51 3.6 7.50 1.2 NDF, % of DM 31.6 17.5 28.9 5.7 ADF, % of DM 21.4 15.8 18.6 17.9 Starch, % of DM 35.4 16.7 40.8 5.0 Sugar, % of DM 2.6 19.6 2.5 8.7 pH 3.88 1.3 3.85 1.5 Lactic acid, % of DM 3.11 26.9 4.14 28.1 Acetic acid, % of DM 3.98 21.5 2.81 27.1 Propionic acid, % of DM 0.51 26.8 0.28 54.3 Butyric acid, % of DM <0.01 0.0 <0.01 0.0 Total acids, % of DM 7.61 10.5 7.22 3.3 DM was calculated using weekly samples and oven dried for 48 h at 60 °C. All other samples are based on monthly composites (n = 4) of weekly (n = 19) samples taken during the finishing trial, and analyzed at Dairyland Laboratories (St. Cloud, MN) and Ward Laboratories (Kearney, NE). C.V. = coefficient of variation and is calculated by dividing the standard deviation by the mean and is expressed as a percentage. Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 4 Hilscher et al. Table 2. Diet composition (% DM basis) for cattle finishing experiment (experiment 1) Treatment 15% Corn silage 45% Corn silage 37% DM 43% DM 37% DM 43% DM High moisture corn 41.0 41.0 11.0 11.0 Modified distillers grains plus solubles 40.0 40.0 40.0 40.0 37% DM corn silage 15.0 — 45.0 — 43% DM corn silage — 15.0 — 45.0 Supplement 4.0 4.0 4.0 4.0 Fine ground corn 1.8048 1.8048 1.8048 1.8048 Limestone 1.7050 1.7050 1.7050 1.7050 Tallow 0.1000 0.1000 0.1000 0.1000 Salt 0.3000 0.3000 0.3000 0.3000 Trace Mineral premix 0.0500 0.0500 0.0500 0.0500 Vitamin A-D-E premix 0.0150 0.0150 0.0150 0.0150 Monensin 0.0165 0.0165 0.0165 0.0165 Tylosin 0.0087 0.0087 0.0087 0.0087 Treatments: 15% silage 37 % DM = 15% concentration of 37% DM silage, 15% silage 43% DM = 15 % concentration of 43% DM silage, 45% silage 37% DM = 45% concentration of 37% DM silage, 45% silage 43% DM = 45% concentration of 43% DM silage; all diets contained 40% MDGS. Supplement was formulated to be fed at 4% of diet DM. Trace mineral premix contained 6% Zn, 5.0% Fe, 4.0% Mn, 2.00% Cu, 0.29% Mg, 0.2% I, and 0.05% Co. Vitamin A-D-E premix contained 30,000 IU of Vitamin A, 6,000 IU of Vitamin D, 7.5 IU of Vitamin E per gram. Monensin (Rumensin-90; Elanco Animal Health, Indianapolis, IN) premix contained 198 g/kg monensin. Tylosin (Tylan-40; Elanco Animal Health, Indianapolis, IN) premix contained 88 g/kg tylosin. a 60  ºC forced-air oven for determination of DM by using pen data in the Galyean (2009) Net energy and calculation of refusal DM weight (AOAC, 1999 calculator based on NRC (1996) net energy equa- method 4.1.03). Dietary ingredients were sampled tions. The calculator uses initial BW, final BW, dry weekly for determination of DM content. Dietary matter intake (DMI), average daily gain (ADG), as-fed ingredient proportions were adjusted weekly. and a target endpoint (assuming choice quality Steers were on feed for an average of 108 d (97 d grade). block 1, 111 d block 2 and 3)  and were harvested Performance and carcass data were analyzed at a commercial abattoir (Greater Omaha Packing, using the GLIMMIX procedure of SAS (SAS Inst. Omaha, NE). On the day of shipping to the com- Inc.) with pen serving as the experimental unit mercial abattoir, pens of steers were fed 50% of the (n  =  5 per treatment) and block (n  =  3) as a fixed previous day’s DM offering at regular feeding time. effect. Data were analyzed as a randomized block Pens of steers were weighed on a platform scale design with BW sort as block. Initial BW was sig- at 1500  h before being loaded for shipping. A  4% nificantly different between silage DM treatments pencil shrink was applied to this BW for final live (1.7 kg) and included as a covariate in the model if BW and calculation of dressing percentage dressing significant. Inclusion of initial BW was not a signif- percentage, calculated as hot carcass weight (HCW) icant covariate for any variables and was removed divided by shrunk live final BW. HCW and liver from the model as a covariate. Significance of abscess scores were obtained the day of harvest. effects was determined at P ≤ 0.05. Liver abscesses were categorized as 0 (no abscesses), A–, A, or A+ (severely abscessed) according to the Experiment 2—Cattle Growing Experiment procedures outlined by Brink et  al. (1990). Liver An 83-d growing study was conducted at the abscess categories were combined to calculate the ENREC near Mead, NE using 60 crossbred steers proportion of steers with abscessed livers in each (BW = 271; SD = 32 kg). Steers were individually pen. Carcass-adjusted final BW, used in the calcula- fed using Calan gate feeders (American Calan Inc., tion of ADG and G:F, was calculated from HCW Northwood, NH). On arrival and before initiation and a 63% common dressing percentage. Marbling of the experiment, steers were identified and pro- score, 12th rib fat thickness, and longissimus mus- cessed as described previously. Cattle were limit-fed cle (LM) area were recorded after a 48  h carcass a diet of 50% Sweet Bran and 50% alfalfa hay at chill. The energy value of the diets was calculated Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 5 2.0% of projected BW for 5 d before trial initia- gluten meal. SoyPass is an enzymatically browned tion to equalize gut fill (Watson et al., 2013). Steers soybean meal and Empyreal is a concentrated corn were weighed 3 consecutive days, with the average gluten meal. Steers were stratified by day –1 and of the 3 d used as initial BW (Stock et  al., 1983). day 0 BW, and assigned randomly to 1 of 10 treat- A randomized block experimental design was used ments arranged in a 2  × 5 factorial arrangement. with treatments arranged in an unbalanced 2  × 5 Steers per level of RUP supplementation included factorial arrangement. The first factor was the base n = 8 for 0.5% RUP; n = 5 for 1.4% and 2.4 % RUP; corn silage growing diet fed at 88% of the diet DM, n  =  6 for 3.3% and 4.2% RUP treatments. With a which consisted of corn silage harvested at either limited number of bunks, a greater number of ani- 37% or 43% DM (Table 3). The second factor was mals were fed at 0.5% RUP concentration (0% RUP response to RUP supplementation at 0.5%, 1.4%, supplement, 100% RDP supplement) to better 2.4%, 3.3%, or 4.2% of the diet DM. The RUP sup- compare the response curve to RUP supplementa- plementation consisted of top dressing a blend of tion. In addition, a greater number of animals were 0/100, 25/75, 50/50, 75/25, or 100/0 combination of fed at 3.3% and 4.2% RUP concentration as it was an RDP and RUP supplement (Table 3). The sup- hypothesized the steers MP needs would be met at plement included RUP source, urea, minerals, vita- greater levels of RUP concentration. When evalu- mins A-D-E, and soybean hulls. Soybean hulls were ating response curves to increasing supplementa- the carrier that along with urea was replaced with tion of RUP, the curves are greatly influenced by the RUP sources. The supplement also included the response on either end of the curve. Therefore, monensin (Elanco Animal Health) and was formu- to ensure accuracy of estimate, steers were not lated to provide 200 mg/steer daily. The RUP sup- equally distributed across supplementation con- plement consisted of 52% SoyPass (50% CP; 75% centrations. However, blocks were balanced within RUP as % CP; Borregaard Lignotech, Rothschild, each supplementation treatment and across the two WI) and 34.7% Empyreal (75% CP; 65% RUP silage harvest treatments. The hypothesis is that a as % of CP; Cargill Inc.) and provided RUP in a nonlinear breakpoint analysis will establish the die- blend of amino acids from soybean meal and corn tary requirement for RUP supplementation, thus Table 3. Diet composition (% DM basis) for cattle growing experiment (experiment 2) Treatment 37% DM 43% Corn silage Ingredient 0.5% 1.4% 2.4% 3.3% 4.2% 0.5% 1.4% 2.4% 3.3% 4.2% 37% DM corn silage 88.0 88.0 88.0 88.0 88.0 — — — — — 43% DM corn silage — — — — — 88.0 88.0 88.0 88.0 88.0 Rumen degradable protein supplement 12.0 9.0 6.0 3.0 0.0 12.0 9.0 6.0 3.0 0.0 Rumen undegradable protein supplement 0.0 3.0 6.0 9.0 12.0 0.0 3.0 6.0 9.0 12.0 Soybean hulls 9.3552 7.1225 4.8897 2.6570 0.4242 9.3552 7.1225 4.8897 2.6570 0.4242 Limestone 0.2120 0.2583 0.3045 0.3508 0.3970 0.2120 0.2583 0.3045 0.3508 0.3970 Salt 0.4000 0.3750 0.3500 0.3250 0.3000 0.4000 0.3750 0.3500 0.3250 0.3000 Urea 1.2000 0.9750 0.7500 0.5250 0.3000 1.2000 0.9750 0.7500 0.5250 0.3000 Tallow 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 0.3000 Dicalcium phosphate 0.4540 0.3905 0.3270 0.2635 0.2000 0.4540 0.3905 0.3270 0.2635 0.2000 Trace mineral premix 0.0500 0.1625 0.2750 0.3875 0.5000 0.0500 0.1625 0.2750 0.3875 0.5000 Vitamin A-D-E premix 0.0150 0.0488 0.0825 0.1163 0.1500 0.0150 0.0488 0.0825 0.1163 0.1500 Monensin 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 0.0138 Bypass soy — 1.5000 3.0000 4.5000 6.0000 — 1.5000 3.0000 4.5000 6.0000 Concentrated corn gluten meal — 1.0000 2.0000 3.0000 4.0000 — 1.0000 2.0000 3.0000 4.0000 Treatments: Diets contained 88% of either 37% or 43% DM corn silage and formulated to contain 0.5%, 1.4%, 2.4%, 3.3%, or 4.2% RUP as a % of total diet. RDP and RUP supplement were formulated for a target concentration of 12%. Combinations of both were used to achieve desired RUP % of the diet DM. Trace mineral premix contained 6% Zn, 5.0% Fe, 4.0% Mn, 2.00% Cu, 0.29% Mg, 0.2% I, and 0.05% Co. Vitamin A-D-E premix contained 30,000 IU of Vitamin A, 6,000 IU of Vitamin D, 7.5 IU of Vitamin E per gram. Monensin (Rumensin-90; Elanco Animal Health, Indianapolis, IN) premix contained 198 g/kg monensin. Enzymatically browned soybean meal 50% CP; 75% RUP as % CP (SoyPass; Borregaard Lignotech, Rothschild, WI) Concentrated corn gluten meal 75% CP; 65% RUP as % of CP (Cargill Inc., Blair, NE). Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 6 Hilscher et al. increased replications were used to establish the Table 4. Diet composition (% DM basis) for lamb baseline (0.5% RUP) and the maximum response digestion experiment (experiment 3) line (3.3% and 4.2% RUP). Steers were treated for Treatment external parasites (StandGuard; Elanco Animal Ingredient 37% DM 43% Corn silage Health) and were implanted with 36  mg zeranol 37% DM corn silage 92.140 — (Ralgro; Merck) on d 1. Feed bunks were assessed 43% DM corn silage — 92.140 at approximately 0600 h and managed to allow for Bypass soy 3.000 3.000 ad libitum intake. Steers were fed ad libitum once c Concentrated corn gluten meal 2.000 2.000 daily at 0800 h. Feed refusals were collected weekly, Urea 0.750 0.750 weighed, and then dried in a 60 °C forced-air oven Limestone 0.100 0.100 for 48 h to calculate an accurate DMI for individual Trace mineral premix 2.000 2.000 Vitamin A-D-E premix 0.015 0.015 steers. Feed ingredients were sampled weekly and analyzed in the same manner for DM, with as-fed Treatments: Diets contained 92.14% of either 37% or 43% DM ingredient proportions adjusted weekly. At the con- corn silage and fed at ad libitum or restricted at 1.5% of BW. clusion of the study, steers were again limit-fed for Enzymatically browned soybean meal 50% CP; 75% RUP as % CP (SoyPass; Borregaard Lignotech, Rothschild, WI). 5 d as described earlier and weighed 3 consecutive Concentrated corn gluten meal 75% CP; 65% RUP as % of CP days to determine ending BW. The energy value of (Cargill Inc., Blair, NE). the diets was calculated by using pen data in the Trace mineral premix contained 6% Zn, 5.0% Fe, 4.0% Mn, 0.29% Galyean (2009) Net energy calculator based on Mg, 0.2% I, and 0.05% Co. NRC (1996) net energy equations. The calculator e Vitamin A-D-E premix contained 30,000 IU of Vitamin A, 6,000 uses initial BW, final BW, DMI, ADG, and target IU of Vitamin D, 7.5 IU of Vitamin E per gram. endpoint (assuming choice quality grade). Intake restriction to 1.5% of BW began on d 8 of Data were analyzed using the MIXED proce- the period 3 d before collection. BW was deter- dure of SAS (SAS Inst. Inc.) as a randomized block mined by weighing 2 consecutive days at the end design in a 2 × 5 factorial arrangement testing for of a period for subsequent restriction calculations linear and quadratic interactions between silage in the next period. During the adaptation period, DM and RUP level with steer serving as the exper- lambs were housed in individual pens with grated imental unit and weight block (n  =  5) as a fixed oors fl , individual feed bunks, and automatic water - effect. If no interactions were detected, the main ers. Feeding occurred twice daily at approximately effects of silage DM and RUP concentration were 0800 and 1500 h, and orts were collected, weighed, evaluated. To evaluate RUP level, linear and quad- and fed back during the adaptation period. ratic contrasts were developed to evaluate the effect At the end of adaptation, lambs were placed in of increasing RUP level. Significance was declared individual metabolism crates and fitted with har - at P ≤ 0.05. nesses and fecal collection bags on the evening of d 10. Total fecal output was collected twice daily Experiment 3—Lamb Digestion Experiment beginning on d 10 at 0800 and 1600 h, weighed, and An 85-d metabolism study using 9 crossbred retained individually in a cooler until the end of the wether lambs (BW  =  30.1; SD  =  4.1  kg) was con- period. Orts were collected at feeding, weighed, and ducted to determine the extent of nutrient digest- retained individually until the end of the period. At ibility in corn silage at two different levels of DM the end of each period, feces and orts were indi- and intake. Lambs were blocked into two blocks vidually composited and mixed on an as-is basis. based on BW and arranged in a 4 × 5 Latin rectan- Three 100 g subsamples were taken and dried in a gle. The metabolism study was five periods in length 60 °C forced-air oven for 48 h for orts and 72 h for with one of four treatments assigned randomly to feces. Dried samples were ground through a 1-mm lambs within each period, allowing each lamb to screen of a Wiley mill. Samples of individual feed- receive each treatment at least once. Treatments stuffs were taken on d 10 and d 14 and dried to were arranged in a 2  × 2 factorial arrangement. correct for DM of each period. Feedstuff samples Factors included corn silage harvested at either 37% were ground first through a 2-mm screen of a Wiley or 43% DM and intake of corn silage ad libitum or mill, composited by period, and a subset of period restricted to 1.5% of BW. The basel diet consisted of composites were ground through a 1-mm screen of 92% corn silage and 8% supplement (Table 4). a Wiley mill. Diet and fecal samples were analyzed The periods were 17 d in length allowing for 10 for DM, organic matter (OM), and NDF. Ground d of adaptation and 7 d for total fecal collection. feed and fecal samples were dried in a 100 °C oven Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 7 for 24 h to determine laboratory-adjusted DM and harvested. Burken et  al. (2017a) harvested corn then incinerated in a muffle furnace at 600  °C for plants at three different time points coinciding with 6 h to determine the ash content to calculate OM. traditional silage harvest with a whole-plant DM of Neutral detergent fiber was determined by refluxing 35.8%, physiological maturity with a whole-plant samples in beakers for 1 h (Van Soest and Marcus, DM of 42.4%, and corn grain harvest. In year 1 of 1964; Van Soest et al., 1991). Total tract apparent the experiment, stover yield and whole-plant yields digestibility was calculated using DM, OM, and responded in a quadratic fashion with both stover NDF disappearance. and whole-plant yields maximized at physiological Total tract digestibility data were analyzed maturity and decreased at corn grain harvest. The using the MIXED procedure of SAS (SAS Inst. authors suggested that this could be due to senes- Inc.) with period and block as fixed effects. Lamb cence and abscission as the stover portion of the was included as a random effect. Lamb served as plant became dry and brittle after physiological the experimental unit, and the model included maturity. In year 2 of the experiment, Burken et al. corn silage DM, intake, and corn silage DM by (2017a) noted linear increases in whole-plant and intake interaction. Significance was declared at stover yields as harvest was delayed from traditional P ≤ 0.05. silage harvest to corn grain harvest. Year-to-year variation will occur in corn silage yield because of RESULTS AND DISCUSSION management and environmental factors; however, Burken et al. (2017a) reported greater whole-plant yield at physiological maturity compared to tradi- Corn Silage and Grain Harvest tional corn silage harvest in both years. Filya (2004) There was an increase (P < 0.01) in yield of DM also reported DM yield in megagrams per hectare megagrams per hectare comparing 37% DM to 43% was maximized at black layer formation that coin- DM corn silage with yields of 21.41 and 22.58 Mg/ cided with 42% whole-plant DM. In addition, Hunt ha (DM), respectively (Table 5). There was no dif- et  al. (1989) reported that as harvest was delayed, ference (P = 0.64) in yield between HMC and dry whole-plant yield and TDN in megagrams per hec- corn grain with 13.72 and 13.80 Mg/ha DM yields, tare increased. These data suggest that grain yield respectively (data not presented). The increase in was maximized when delaying corn silage harvest DM yield is the result of increased grain develop- until black layer formation. In addition, high-mois- ment, as the plant matures, the grain fraction of ture corn was harvested 3 d after the 43% DM the plant is increased as more nutrients are shut- silage was harvested further suggesting grain yield tled into the corn kernels for them to fully develop. was maximized. No further yield increase for grain Suazo et  al. (1991) reported that across multiple was observed between this time point and dry grain hybrids, whole-plant DM yield in this study was harvest. maximized at black layer formation and grain yield in megagrams per hectare did not differ from black layer to corn grain harvest. Darby and Lauer (2002) Experiment 1—Cattle Finishing Experiment reported that whole-plant DM yield increased as There were no interactions between corn silage the growing season was lengthened and more grow- DM and corn silage concentration (P ≥ 0.47) for ing degree days occurred. Maximum DM yield was feedlot performance or carcass characteristics achieved when whole-plant DM reached 42% DM, (Table 6). As concentration of corn silage in the which occurred at the latest date the researchers Table 5. Delayed corn silage dry matter and yield Treatments Early harvest Late hrvest SEM P value Item Mean SD Mean SD Silage DM , % 37.3 1.2 42.7 1.7 Silage yield, DM Mg/ha 21.41 0.52 22.58 0.13 0.19 <0.01 Early harvest corn silage harvested at whole-plant DM = 37.3% DM and kernel milk = ¾ harvested on September, 4, 2014. Late harvest corn silage harvested at whole-plant DM = 42.7% DM and kernel black layer formation harvested on September 16, 2014. DM was calculated using weekly (n = 19) samples and oven dried for 48 h at 60 °C. Coefficient of variation was 3.2 for early harvest and 3.9 for late harvest based on weekly DM samples. Silage yield = total DM Mg/ha at 100% DM. Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 8 Hilscher et al. Table 6. The effects of delayed corn silage harvest and increased concentrations of corn silage on feedlot performance and carcass characteristics of cross bred yearling steers (experiment 1) Treatments 15% Corn silage 45% Corn silage P value b c d Variable 37% DM 43% DM 37% DM 43% DM sem Int. Concentration DM Feedlot performance Initial BW, kg 426 427 426 427 0.5 0.77 0.87 <0.01 Final BW , kg 621 626 608 608 7.0 0.71 0.04 0.68 Live final BW, kg 638 649 635 640 9.7 0.76 0.54 0.44 DMI, kg/d 13.0 13.2 13.3 13.5 0.2 0.82 0.15 0.30 ADG, kg 1.85 1.87 1.72 1.71 0.07 0.79 0.04 0.90 G:F 0.142 0.142 0.129 0.126 0.003 0.79 <0.01 0.64 NE , Mcal/kg DM 1.81 1.80 1.68 1.66 0.03 0.88 <0.01 0.62 NE , Mcal/kg DM 1.17 1.16 1.06 1.04 0.02 0.83 <0.01 0.53 Carcass characteristics Hot carcass weight, kg 391 394 383 383 4.4 0.71 0.04 0.68 Dressing percentage, % 61.1 60.8 60.2 59.8 0.56 0.93 0.05 0.68 Longissimus area, cm 84.38 82.63 84.78 83.36 0.89 0.85 0.52 0.08 12th-rib fat, cm 1.28 1.40 1.26 1.28 0.08 0.47 0.26 0.27 Marbling score 514 498 489 493 14.0 0.48 0.29 0.67 Treatments: 15% silage 37% DM = 15% concentration of 37% DM silage, 15% silage 43% DM = 15% concentration of 43% DM silage, 45% silage 37% DM = 45 % concentration of 37% DM silage, 45% silage 43% DM = 45 % concentration of 43% DM silage; all diets contained 40% MDGS. Silage concentration × silage DM interaction. Fixed effect of silage concentration. Fixed effect of silage DM. Final BW, were calculated based on HCW/common dressing percent of 63%. NE and NE were calculated using methodology of NRC (1996) using a tool developed by Galyean (2009) assuming a 625 kg target endpoint. m g Marbling score 400 = small00, 500 = modest00. finishing diet increased from 15% to 45%, ADG As corn silage concentration increased from 15% decreased (P  =  0.04) whereas DMI did not differ to 45%, DMI, ADG, and G:F decreased linearly, (P = 0.15), and this, in turn, led to a decrease in but when comparing diets with 45% corn silage, the G:F (P < 0.01). Goodrich et al. (1974) reported lin- diet with 40% MDGS had greater ADG and G:F ear decreases in ADG and G:F as corn silage was compared to 45% silage with 0% MDGS. Although increased in the finishing diet. Similarly, Gill et al. performance was reduced when feeding greater (1976) observed decreased G:F as corn silage was concentrations of corn silage and distillers grains increased in the finishing diet. Brennan et al. (1987) plus solubles (DGS), the decrease in performance is reported no difference in DMI, ADG, or G:F less with DGS in the diet compared to in previous between cattle fed 41% and 23% corn silage in fin- studies without DGS. ishing diets. Erickson (2001) evaluated corn silage in Calculated net energy for maintenance (NE ) finishing diets at 15%, 30%, or 45% of diet on a DM and net energy for gain (NE ) values were decreased basis. In two trials with yearling cattle, DMI was not (P  <  0.01) as corn silage concentration increased affected by treatment, but ADG and G:F decreased from 15% to 45% of the diet DM. Preston (1975) as corn silage concentration increased from 15% to summarized experiments where corn silage replaced 45% of the diet. In a trial with calf feds, Erickson corn grain up to 64% of the diet and reported linear (2001) reported that DMI increased as corn silage decreases in NE and NE values as concentration m g concentration increased; however, ADG and G:F of corn silage increased. Similarly, Burken et  al. both linearly decreased with increased corn silage. (2017a) reported linear decreases in NE by 4% At present, Burken et al. (2017a) fed increased con- (2.00 to 1.92) and NE by 4.5% (1.34 to 1.28) values centrations of corn silage at 15%, 30%, 45%, and as corn silage concentration increased from 15% to 55% with modified distillers grains plus solubles 55% of the diet DM. Although performance was (MDGS) concentration of 40% (DM basis) and an reduced when feeding high levels of corn silage and additional diet of 45% corn silage and no distillers DGS, the decrease in performance is less with DGS in finishing diets to evaluate animal performance. in the diet compared to previous studies without Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 9 DGS. Burken et  al. (2017a) fed 40% MDGS in increase in DMI. There was no difference in ADG the diet and increased the amount of corn silage between steers fed 28% and 42% DM silage; how- in the diet from 15% to 45%, which resulted in a ever, there was a numerical increase in ADG and 5% reduction in G:F. However, without DGS in G:F for steers fed 42% DM silage. Browne et  al. the diet, both Goodrich et al. (1974) and Erickson (2004) compared silages harvested at 29.1%, 33.9%, (2001) reported a 15% reduction in G:F when and 39.3% whole-plant DM in European style fin- increasing silage concentration from 15% to 45%. ishing systems with 89% corn silage included in the As corn silage concentration increased from 15% to finishing diet. The authors found that as harvest 45%, ADG and G:F decreased due to the decrease was delayed, DMI increased and G:F decreased; in dietary energy content as corn silage is lower in however, final BW, HCW, and ADG were not differ - net energy compared to the corn gain it replaced in ent. These data tend to support a lack of difference the finishing diet. in finishing diets with 15% to 45% silage, or rela- Carcass-adjusted final BW and HCW were tively low inclusions when corn silage is harvested reduced (P ≤ 0.04) for steers fed 45% corn silage between 25% and 44% DM. It is unclear if the lack compared to 15%. Burken et al. (2017a) reported a of differences due to harvest DM is due to low linear decrease in final BW and HCW as corn silage inclusions and masking any difference in silage or was increased in finishing diets. In two additional if just no difference exists between harvest DM of studies by Burken et al. (2017b), they reported that silage when fed in finishing diets. Similar to ADG final BW and HCW tended to decrease in the first and G:F in this study, no differences (P ≥ 0.27) in experiment and significantly decreased in final BW dressing percent, 12th rib fat, or marbling scores and HCW in the second experiment as concentra- were observed as DM of corn silage was increased. tion of corn silage increased from 15% to 45% of In finishing diets, increasing silage inclusion the diet. Dressing percentage decreased (P  =  0.05) from 15% to 45% of diet DM decreases ADG as concentration of corn silage was increased from and G:F that agrees with previous work, but the 15% to 45% in the finishing diet. When cattle are decreases are less than some previous studies, par- fed elevated concentrations of corn silage, dress- ticularly those without distillers grains. Whether ing percentage decreases due to increased gut fill. silage was harvested at a DM of 37% or 43% DM Peterson et  al. (1973) reported that as corn silage did not affect ADG or G:F in finishing cattle. concentration increased, dressing percentage lin- early decreased. Similarly, Brennan et  al. (1987) Experiment 2—Cattle Growing Experiment reported cattle fed increased concentrations of corn There were no linear (P ≥ 0.33) or quadratic (P silage had decreased dressing percentages. Burken ≥ 0.36) interactions between corn silage DM and et al. (2017a) reported a linear decrease in dressing level of RUP supplementation for growing perfor- percentage as corn silage concentration increased. mance. As DM of corn silage increased from 37% There were no differences (P ≥ 0.31) in LM area, to 43%, there was a significant decrease (P = 0.04) 12th rib fat, and marbling score as concentration in ending BW (Table 7). There was no difference of corn silage concentration increased. Burken (P = 0.93) in DMI between 37% and 43% DM corn et al. (2017b) also reported no differences in carcass silage, and ADG was reduced (P = 0.01) as DM of characteristics when silage was fed at 15% or 45% silage increased, which led to a significant decrease of the diet. (P < 0.01) in G:F. Worley et al. (1986) fed silage har- As DM of corn silage increased from 37% to vested at 31% or 44% whole-plant DM to growing 43% due to delaying harvest, there were no differ- heifers. The authors reported decreased ADG and ences (P ≥ 0.30) in DMI, ADG, or G:F. In addition, G:F in the first 28 DOF when feeding drier silage, there were no differences (P = 0.68) in carcass-ad- similar to this study. Although overall performance justed final BW or HCW as corn silage DM was from d 0 to d 70 was not statistically different, the increased. Chamberlain et  al. (1971) compared 44% DM silage had numerically lower ADG and corn silage in finishing diets (27% of diet DM) G:F. Chamberlain et  al. (1971) compared corn harvested from 25% to 44% whole-plant DM, and silage in growing diets (70% of diet DM) harvested as harvest maturity increased, there were no dif- from 25% to 44% whole-plant DM. There were no ferences in final BW, DMI, ADG, or G:F in the differences in ADG between the first three stages finishing period across all corn silages. Buchanan- of maturity harvested at 25%, 30%, and 36.5% Smith (1982) compared corn silage harvested at DM, but the latest maturity harvested at 44% DM 28% or 42% whole-plant DM in finishing steers and had the lowest ADG. Intake was lowest for latest reported that steers fed 42% DM silage had a 5% Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 10 Hilscher et al. harvested corn silage and G:F decreased as harvest (Table 8). There was a linear increase (P = 0.05) in was delayed. When evaluating corn silage harvested DMI as RUP concentration increased in the grow- at ½ milk line (28.4% DM) or black layer (42.5% ing diet. Daily gain improved as RUP concentration DM), Andrae et  al. (2001) reported decreases in increased in the growing diet, with ADG increasing total tract starch, NDF digestibility (NDFD), and (P < 0.01) linearly from 0.5% to 4.2% RUP concen- ADF digestibility (ADFD) by 6.5, 5.9, and 7.5 per- tration. With a greater increase in ADG compared centage units, respectively. The authors concluded to the increase in DMI, G:F increased (P  <  0.01) that NDFD and ADFD decreased due to increased linearly as RUP concentration increased. Steers fed lignification, and also the increased starch content the 4.2% supplemental RUP treatment were 19.9%, from the more mature corn silage caused an unfa- 14.5%, 5.9%, and 2.7% more efficient than steers vorable rumen environment with lower pH that supplemented with 0.5%, 1.4%, 2.4%, or 3.3% RUP, hindered fiber digestion. Calculated NE and NE respectively. m g values were significantly lower (P = 0.03) for 43% Ingredients can vary in RUP content as well DM compared to 37% DM corn silage. These stud- as RUP digestibility. Corn grain is the most com- ies suggest some consensus that dryer silage fed to monly fed grain in the United States, and dry corn growing steers reduces ADG and G:F and is likely grain has a RUP value of approximately 65.3% due to either decreases in fiber digestion due to (NASEM, 2016). Corn processing method impacts more mature plants or more starch concentration RUP %. Work by Benton et al. (2005) showed that that decreases fiber digestion in the rumen. when grain is harvested as HMC, the RUP content As supplemental RUP in the growing diet of corn grain decreases, and it becomes more rumen increased from 0.5% to 4.2% of total diet, end- degradable as the moisture content and length of ing BW increased linearly (P  <  0.01) with steers ensiling period increases. The corn grain in silage receiving 4.2% RUP as a % of total diet having is harvested earlier than HMC and wetter, suggest- the heaviest ending BW and steers receiving 0.5% ing a further increase in RDP content of the corn supplemental RUP having the lowest ending BW grain in corn silage. The NASEM (2016) lists the Table 7. Effects of delayed corn silage harvest on growing steer performance (experiment 2) Treatments Item 37% DM 43% DM SEM P value Initial BW, kg 271 271 1.8 0.92 Ending BW, kg 384 375 3.0 0.04 DMI, kg/d 8.2 8.1 0.1 0.93 ADG, kg 1.45 1.33 0.03 0.01 G:F 0.177 0.164 0.001 <0.01 NE , Mcal/kg DM 1.73 1.65 0.02 <0.01 NE , Mcal/kg DM 1.11 1.04 0.02 <0.01 Treatments: steers were fed 88% of either 37% or 43% DM corn silage. NE and NE were calculated using methodology of NRC (1996) using a tool developed by Galyean (2009) assuming a 625 kg target endpoint. m g Table 8. The effects of increased concentration of RUP in silage based growing diets on performance of cross bred steers (experiment 2) Treatments Variable 0.5% 1.4% 2.4% 3.3% 4.2% SEM Lin. Quad. Initial BW, kg 270 271 271 270 272 2.4 0.98 0.60 Ending BW, kg 359 374 388 382 394 4.1 <0.01 0.88 DMI, kg/d 7.7 8.3 8.6 7.9 8.3 0.2 0.05 0.84 ADG, kg 1.14 1.32 1.50 1.43 1.56 0.04 <0.01 0.82 G:F 0.149 0.159 0.175 0.181 0.186 0.002 <0.01 0.57 NE , Mcal/kg DM 1.58 1.63 1.71 1.77 1.79 0.04 <0.01 0.57 NE , Mcal/kg DM 0.97 1.02 1.09 1.14 1.16 0.03 <0.01 0.57 Treatments: Diets contained 88% of either 37% or 43% DM corn silage and formulated to contain 0.5%, 1.4%, 2.4%, 3.3%, or 4.2% RUP % of total diet. NE and NE were calculated using methodology of NRC (1996) using a tool developed by Galyean (2009) assuming a 625 kg target endpoint. m g Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 11 RUP content for corn silage as 25.38% (% of CP). was different. The DDGS and SBM supplemented When evaluating the RUP value of forages, work treatments had greater final BW, DMI, ADG, and by Kononoff et  al. (2007) found that the digesti- G:F. As corn silage is lacking in the protein neces- bility of forage RUP is much lower than the 80% sary to meet MP requirements in growing calves, suggested by the NRC (1996). Specifically looking supplementing with protein such as DDGS or SBM at corn silage, Kononoff et  al. (2007) estimated that has more RUP than urea benefited these grow- RUP (% of CP) to be 19.25%, but with an intesti- ing calves compared to increased RDP in the urea nal RUP digestibility of only 19.9%. Much of the treatment. All these studies, along with results from protein in silage is fermented to soluble protein in experiment 2, suggest the MP requirement is larger the bunker and to ammonia in the rumen. Such than previously thought or corn silage is provid- degradation reduces the amount of intact pro- ing less digestible RUP than previously thought. tein and amino acids available in the small intes- More research is needed on RUP concentration tine as RUP (Owens et  al., 2018). The level and and digestibility to accurately model MP supply degradability in the rumen of protein can have a compared to requirements for the growing calves in large impact on growing steer performance. Byers experiment 2. and Moxon (1980) fed corn silage-based growing diets (55% of diet DM) and three levels of pro- Experiment 3—Lamb Digestion Experiment tein, 11.6%, 14.1%, or 16.5%, to growing steers There was no interaction between corn silage (average initial BW  =  233  kg). The additional CP DM and intake level for DM and OM intake and in these supplements came from increased soybean digestibility, and the main effects will be presented. meal (44% RUP; NASEM, 2016) and linseed meal Owing to intake restriction between ad libitum and (32% RUP; NASEM, 2016). As CP increased from lambs held at 1.5% of BW, there was a significant 11.6 to 16.5, DMI, ADG, and G:F significantly (P  <  0.01) decrease in DMI and OM intake for increased. This indicated that calves fed 11.6% CP restricted lambs as designed (Table 9). There were were not meeting their MP requirements, therefore no differences (P  =  0.56) in DM digestibility and limiting growth. Perry et al. (1983) fed corn silage OM digestibility between silage harvest and intake (92% of diet DM) to growing steers (average ini- level. Worley et  al. (1986) fed silage harvested at tial BW = 213 kg) with supplemental soybean meal 31% or 44% whole-plant DM either ad libitum or to achieve CP levels of 9%, 11%, or 13% of DM. restricted to growing lambs. The authors reported Increasing the level of CP in the diet increased greater DMI for 44% DM corn silage when fed ad DMI, ADG, and G:F of these growing calves. libitum, but there were no differences in DM digest- Although Byers and Moxon (1980) and Perry et al. ibility between silage DM when fed ad libitum or (1983) concluded that increased dietary protein in restricted. Johnson and McClure (1968) reported silage based growing diets improves performance, it greater DMI as whole-plant DM increased to is actually RUP of supplemental CP that had a sig- 33.9% DM and remained constant up to 46% nificant impact on performance because the addi- when fed to growing lambs. The authors reported tion of urea (100% RDP) does not have the same DM digestibility and OM digestibility were signif- magnitude of increase as the RUP supplements that icantly affected by harvest DM over a broad range were used in those trials. Felix et  al. (2014) com- of harvest DM. Between 33.9% and 42.6% DM, pared corn silage-based (90% of DM) diets with DM digestibility changes were minimal: 68.2% vs. increased levels of CP at 11%, 12%, and 13%, and 68.9% for 33.9 and 42.6% DM silages, respectively. only urea was used to increase CP. When increasing When feeding beef steers, Joanning et  al. (1981) the CP through increased urea in silage diets fed to reported no difference in DM digestibility between growing calves (initial BW  =  198  kg), the authors corn silage harvested at 22% or 35% DM. Similarly, reported a linear decrease in ending BW, ADG, and McGeough et al. (2010) reported no differences in G:F and increasing the amount of RDP did not DMI or DM digestibility between silage harvested increase the microbial crude protein supply enough at four different maturities. to maximize growth. Felix et  al. (2014) compared There was an intake × harvest time interaction silage-based (79% on DM basis) growing diets with for NDF intake and therefore the simple effects will sources of supplemental protein on animal perfor- be discussed. Concentration of NDF was lower in mance. The authors compared silage growing diets 43% DM silage so lambs restricted to 1.5% BW for and formulated diets to be iso-nitrogenous with a intake had lower NDF intake than 37% DM. The CP of 10.8%; however, the source of supplemen- interaction was observed because the magnitude of tal protein, urea, DDGS, or soybean meal (SBM), Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 12 Hilscher et al. Table 9. Effect of delayed corn silage harvest and intake restriction on digestibility in lambs (experiment 3) Treatments Ad libitum Limited P value b c d Item 37% DM 43% DM 37% DM 43% DM SEM Int. Intake DM DM Intake, kg/d 2.14 1.99 1.16 1.15 0.08 0.28 <0.01 0.23 Digestibility, % 70.8 71.5 71.9 71.1 1.3 0.56 0.76 0.97 OM Intake, kg/d 2.01 1.89 1.09 1.09 0.08 0.33 <0.01 0.39 Digestibility, % 72.6 73.3 73.7 73.1 1.3 0.56 0.67 0.99 NDF Intake, kg/d 1.07 0.77 0.58 0.45 0.03 <0.01 <0.01 <0.01 Digestibility, % 63.4 53.3 65.4 53.5 0.02 0.67 0.60 <0.01 Treatments: Diets contained 92.14% of either 37% or 43% DM corn silage and fed at ad libitum or restricted at 1.5% of BW. Silage intake × silage DM interaction. Fixed effect of silage intake. Fixed effect of silage DM. difference in NDF intake was even greater when delayed in growing lambs (Johnson and McClure, lambs were fed ad libitum, which was due to lower 1968). Joanning et al. (1981) reported that as silage NDF concentration and numerically lower DMI DM increased from 22% to 35% DM, there was a for 43% DM silage compared to 37% DM silage. decrease in NDFD of 14.6 percentage units in a 90% In general, intake of NDF was reduced (P < 0.01) silage diet. Jensen et  al. (2005) reported decreased when intake was restricted as expected but also NDFD as harvest DM increased from 35% to 40% reduced (P  <  0.01) for lambs fed 43% DM corn DM. Similar to decreased NDF digestion by lambs silage compared to 37% DM corn silage. The NDF in experiment 3, all studies show decreased fiber concentration of the silage was decreased and starch digestibility as silage harvest is delayed (i.e., DM concentration increased as corn silage harvest was increased in silage). Delaying silage harvest allows delayed. As silage harvest was delayed from 37% to for increased grain yield as a percentage of whole- 43% DM, there was a significant decrease (P < 0.01) plant yield, with no impact on OM digestion, but in NDFD from 64.39% to 53.41%. Worley et  al. delaying silage harvest decreases NDF content in (1986) reported greater NDF intake in 44% DM this study and many others. corn silage compared to 31% DM but reported no Delaying corn silage harvest increased corn difference in NDFD when lambs were fed ab libi- silage yield and maximized grain yield. Although tum or had intake restricted. The corn silage used increasing corn silage concentration from 15% to by Worley et al. (1986) increased in NDF concen- 45% in place of corn in finishing diets reduced ADG tration as corn silage harvest was delayed, this is and G:F, there were no differences in performance not in agreement with previous work that shows when corn silage harvest was delayed from 37% to NDF concentration decreases as corn silage har- 43% DM in these finishing diets. However, delayed vest is delayed, and could explain why these authors corn silage harvest in growing diets indicates that reported increased NDF intake. Jensen et al. (2005) 37% DM silage would result in greater ADG and reported NDF intake decreased as whole-plant DM G:F compared to feeding 43% corn silage. As corn increased from 35% to 40% DM. As corn silage is silage harvest is delayed, plant NDF decreases at harvested later in the harvest season with advanced the expense of corn grain being maximized and maturity, whole-plant NDF decreases (Bal et  al., NDF intake and digestibility decrease. Increasing 1997; Di Marco et al., 2002; Ferraretto and Shaver, the amount of RUP in silage growing diets resulted 2012). Andrae et  al. (2001) reported that as the in linear increases in DMI, ADG, and G:F. These corn plant matures, the NDF content of the corn results indicate that the addition of RUP into silage plant decreased from 43.67% to 38.43% NDF growing diets will improve performance by supply- when harvested at 28.4% and 42.4% DM, respec- ing more MP. tively. These authors also reported digestibility of Although increasing the concentration of corn the NDF decreased from 39.11% to 33.21% when silage in the finishing diet resulted in decreased per - corn silage harvest was delayed. Fiber digestibility formance compared to lower concentrations, the significantly decreased as corn silage harvest was potential for increasing net farm income may be Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/article-abstract/3/2/txz011/5382070 by Ed 'DeepDyve' Gillespie user on 19 March 2019 Corn silage moisture impact on cattle 13 Byers,  F.M., and A.L.  Moxon. 1980. Protein and selenium increased. Economic analysis was not performed, levels for growing and finishing beef cattle. J. Anim. Sci. but by reducing cost of gain during the finishing 50:1136–1144. doi:10.2527/jas1980.5061136x. period and recycling of nutrients from feedlot Chamberlain, C.C., H.A. Fribourg, K.M. Barth, J.H. Felts, and manure to farm fields, an opportunity may exist to J.M. Anderson. 1971. Effect of maturity of corn silage at increase farm profits. harvest on the performance of feeder heifers. J. Anim. Sci. 33:161–166. doi:10.2527/jas1971.331161x. 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