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Simple Summary: During diet transition periods, ruminal acidosis can have negative effects on gut health and performance of ruminants and investigating feed additives that may help alleviate some of these negative effects is critical. Butyric acid and zinc have been studied as feed additives that can improve gastrointestinal health in ruminants and may be suitable to help decrease negative effects of ruminal acidosis. Thus, a study was conducted to evaluate if a partially encapsulated butyric acid and zinc feed additive was effective at improving growth performance, carcass characteristics, and gastrointestinal health in feedlot lambs abruptly transitioned to a 100% concentrate diet. Butyric acid is attributed to gastrointestinal epithelial development and health and two studies were conducted to determine if supplementing encapsulated butyric acid and zinc (BZ) in lambs abruptly transitioned to a finishing diet has effects on growth performance, efficiency of dietary net energy utilization, rumen morphometrics, small intestinal histology, and carcass traits. Polypay wethers (n = 84; initial shrunk body weight = 38.8 kg ± 4.8 kg) were used in a randomized complete block design study. Wethers were abruptly transitioned from a high roughage-based diet to a 100% concentrate-based diet and dietary treatments were 0 or 2 g BZ/kg of diet dry matter. Study 1 evaluated growth performance and carcass traits of lambs over a 59.5 d feeding period, and Study 2 evaluated changes in rumen morphometrics and small intestine histology in serial harvested lambs. Wethers supplemented with BZ had increased body wall thickness, decreased calculated boneless closely trimmed retail cuts, and decreased red meat yield (p ≤ 0.03) compared to non-supplemented wethers. Linear effects (p ≤ 0.01) for harvest date were observed for most rumen and small intestine measurements. Supplementing wethers with BZ did not improve growth performance, carcass traits, or rumen and small intestine measurements. The effects of BZ supplementation on fat deposition in ruminants should be further investigated. [ABSTRACT FROM AUTHOR]

Two randomized complete block design experiments evaluated the influence that varying degrees of ingredient inclusion accuracy in a finishing diet have on growth performance and carcass traits. Treatments included (1) normal inclusion tolerance with a 0.454 kg tolerance for all ingredients (CON) or (2) variable inclusion tolerance where each ingredient was randomly increased or decreased but the targeted as-fed quantity for the daily delivery was met (VAR). In Experiment. 1, black Angus heifers (n = 60; initial shrunk BW = 460 ± 26.2 kg) were used in a 112 d experiment. Ten pens in total (5 pens/treatment, 6 heifers/pen) were used. The targeted diet (DM basis) consisted of high-moisture ear corn (75%), dried distiller's grains (20%), and a liquid supplement (5%). As-fed inclusion rates for DDGS and LS varied from formulated targets by −20, −15, −10, −5, 0, +5, +10, +15 or +20%. The HMEC inclusion was adjusted so that the targeted as-fed amount of the diet was delivered daily. Treatment did not alter ADG, DMI, G:F, HCW, dressing percentage, rib-eye area, rib fat, USDA marbling score, KPH, yield grade, retail yield, empty body fat, or body weight at 28% estimated EBF, nor liver abscess prevalence or severity (p ≥ 0.15). In Exp. 2, Charolais–Angus cross steers (n = 128; initial shrunk BW = 505 ± 32.1 kg) were used in a 94 d experiment. Steers were assigned to pens (8 pens/treatment; 8 steers/pen) and one of the two management strategies used in Exp. 1 was employed. Ractopamine HCl was fed (300 mg per head daily) during the final 28 d. Diets consisted of (DM basis) dry-rolled corn (63%), dried distiller's grains plus solubles (15%), liquid supplement (5%), grass hay (7%), and corn silage (10%). Ingredient inclusions were randomized in the same manner as Exp. 1, except LS inclusion was held constant. Corn silage inclusion was adjusted so that the targeted as-fed amount of the diet was delivered each day. Steers from VAR had increased (p = 0.01) DMI, but similar (p = 0.75) ADG resulting in reduced (p ≤ 0.02) G:F and growth-performance-predicted Net Energy for maintenance and gain. Treatment did not influence (p ≥ 0.38) HCW, dressing percentage, rib-eye area, rib fat, KPH, yield grade, retail yield, empty body fat, or body weight at 28% estimated EBF. A tendency for an increased USDA marbling score (p = 0.08) was noted in VAR. Under the conditions of this experiment, randomly altering ingredient proportions can impact growth performance and efficiency measures depending upon the type of finishing diet fed. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of calcium magnesium carbonate (CMC) and/or tylosin phosphate (TYL) supplementation on behavior, rumination activity, growth performance and carcass characteristics of yearling beef steers. Treatments were arranged in a 2 × 2 factorial including CMC and TYL. Beef steers (n = 156; 469 ± 18 kg) were randomly assigned to treatment pens (7 to 8 steers/pen) with pen (n = 20 pens total, 10 pens/main effect mean, and 5 pens/simple effect mean) as experimental unit. Cattle were transitioned from a 30% roughage diet to a 7% roughage finishing diet based on dry-rolled corn, dried distillers grains plus solubles, liquid supplement, and oat silage over the initial 20 d period. The CMC was included at 1.5% of the diet (DM basis) in replacement of dryrolled corn and TYL was provided at 90 mg·animal·d-1. Behavior and rumination activity were monitored during a 24 h period on d 42. Data was collected on a pen-basis, every 10 min from 0800 h to 0750 h the next day and included minutes spent drinking (DR), eating (EA), active (AC), ruminating (RU), and resting (RE). Cattle were shipped for harvest on d 105 to a commercial beef abattoir. Growth performance was calculated on a carcass-adjusted basis (HCW/0.625). Data were analyzed as a randomized complete block design with fixed effects of CMC, TYL, or their interaction; block was a random effect. An interaction was observed between CMC and TYL for time spent DR (P = 0.03) and RU (P = 0.01). Control steers ruminated 28% longer compared with CMC/-TYL steers (P = 0.05) and 20% longer than -CMC/TYL steers (P = 0.05). The main effect of CMC tended to increase time spent EA by 19.3% (P = 0.06). Dry matter intake was decreased (P = 0.02) by 4.57% when CMC was fed and increased by 1.96% when TYL was fed. However, no difference (P = 0.26) was observed for G:F or gain efficiency in either treatment. No differences (P = 0.28) were observed in any dietary net energy utilization outcomes in either main effect treatment. Carcass weight tended (P = 0.07) to be lighter with CMC supplementation compared with CON (432 vs 439 kg). Supplementation of TYL resulted in a 11.7% reduction (P = 0.04) in percentage of abscessed livers. No differences (P = 0.12) were observed in DP, marbling, YG, or EBF in either main effect treatments. These results indicate that supplementation of CMC did not result in any appreciable improvements in growth, carcass or dietary net energy utilization performance, but TYL supplementation resulted in a positive effect on liver abscess prevalence. [ABSTRACT FROM AUTHOR]

The objective of this research was to determine the influence manger space restriction had on program fed feedlot heifers during the growing phase. Charolais × Angus heifers [initial body weight (BW) = 329 ± 22.1 kg] were used in a 109-d backgrounding phase study. Heifers were received from a ranch in western South Dakota approximately 60 days before study initiation. Initial processing (53 days before study initiation) included individual BW measurement, application of a unique identification tag, vaccination against viral respiratory pathogens (Bovi-Shield Gold 5, Zoetis, Parsippany, NJ) and clostridial species (Ultrabac/Somubac 7, Zoetis), and administration of doramectin pour-on (Dectomax, Zoetis) for control of internal and external parasites. All heifers were administered 36 mg of zeranol (Ralgro, Merck Animal Health, Madison, NJ) at study initiation. Upon study initiation, heifers were assigned to 1 of 10 pens (n = 5 pens/treatment with 10 heifers/pen) in a randomized complete block design (blocked by location). Each pen was randomly assigned to 1 of 2 treatments: 20.3 cm (8IN) or 40.6 cm (16IN) of linear bunk space/heifer. Heifers were individually weighed on days 1, 14, 35, 63, 84 and 109. Heifers were programmed to gain 1.36 kg daily based on predictive equations for a medium frame steer calf set forth by the California Net Energy System. To calculate predictive values, a final BW of 575 kg was assumed to be the mature BW of the heifers and tabular net energy values of 2.05 NEm and 1.36 NEg from d 1 to 22, 2.00 NEm and 1.35 NEg from d 23 to 82, and 1.97 NEm and 1.32 NEg from d 83 to 109 were used, because of ingredient inventory changes. Data were analyzed using the GLIMMIX procedure of SAS 9.4 with manger space allocation as the fixed effect and block as the random effect. No differences (P > 0.35) were observed between 8IN or 16IN heifers for initial BW, final BW, average daily gain, dry matter intake, feed efficiency, variation in daily BW gain (within pen standard deviation) or applied energetic measures. No differences (P > 0.50) were observed between treatments for morbidity. Although not statistically analyzed, 8IN heifers appeared to have looser stools during the first two weeks compared with the 16IN heifers. These data suggest restricting manger space allocation from 40.6 cm to 20.3 cm did not negatively influence gain efficiency or the efficiency of dietary net energy utilization in heifers programmed fed a concentratebased diet to gain 1.36 kg daily. The use of tabular net energy values and required net energy of maintenance and retained energy equations are an effective means to program cattle to a desired daily rate of gain during the growing phase. [ABSTRACT FROM AUTHOR]

Forage and concentrate-based diets are distinct strategies used in ruminant production. The transition from a forage-based diet to a concentrate-based diet has been shown to have a great impact on the rumen microbiome composition due to vast differences in substrates provided by each diet type. To gain further insight on the nature of the changes that occur in the rumen microbiome as a result of a switch in diet, ruminal bacterial composition was compared between lambs initially fed a forage-based diet and lambs that were switched to a concentrate-based diet for approximately 60 days. From rumen fluid that was collected after slaughter, data were generated by Illumina MiSeq 2X300 sequencing of PCR amplicons targeting the V1-V3 regions of the 16S rRNA gene. Next-Generation Sequence data were analyzed using a combination of custom Perl scripts, and publicly available software (Mothur (v.1.35.1), RDP classifier and NCBI Blast). A total of 10,693 species-level operational taxonomic units (OTUs) were identified across all samples, with 86 OTUs shared between diets. A comparative analysis using the non-parametric Kruskal-Wallis test identified 16 highly represented species-level OTUs that differed in abundance across dietary treatments (P < 0.05). Of these, three OTUs, RA-01223, RA1-35340, and RA1-55937, were found to be of particular interest. OTU RA-01223 was at its highest representation in samples from individuals given a concentrate-based diet, with an average abundance of 8.76% compared with 0.80% in samples from animals fed a forage-based diet. RA-01223 was predicted to be a novel species of the family Oscillospiraceae based on its low 16S rRNA gene sequence identity (94.8%) to its closest valid relative, Ruminococcoides bili. OTU RA1-35340, predicted to be a strain of Sharpea azabuensis, was also in much greater abundance in the concentrate-based diet as compared with the forage-based diet (2.83% and 0.05%, respectively). In contrast, RA1-55937, which was predicted to be a strain of Pectinatus haikarae, was at its greatest abundance in samples from individuals given a forage-based diet, with an average representation of 4.91% compared with 0.52% in samples from animals fed a concentrate-based diet. These and other specific ruminal OTUs whose abundance are affected by changes in diet can then be studied further to gain more insight on the effects of the transition from forage to concentrate on rumen physiology. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine if additional roughage inclusion to feedlot steer finishing diets during the feeding of ractopamine hydrochloride (RH) is an effective method to improve rumen health and control liver abscess severity. Steers [n = 64; initial shrunk body weight (SBW) = 633 kg ± 35.1 kg] were sourced from an unrelated trial and remained in their previous study pens; pens (n = 8) were assigned to dietary treatment in a completely randomized design. All steers on trial were fed a common 7% [dry matter (DM) basis] roughage equivalent (RE) finishing diet composed of dry-rolled corn, dried distillers grains plus solubles, corn silage, and grass hay for the 58 d preceding study initiation. Steers were fitted with rumination tags to track daily rumination. Dietary treatments were CON: no diet change; and 12R: 5% (DM basis) RE addition to diet via grass hay during the feeding of RH. Steers were fed RH (300 mg/steer/d), finished on treatment diets for 28 d, and harvested at a commercial beef processor. Growth performance, efficiency of dietary net energy (NE) utilization, and continuous carcass data were analyzed with pen as the experimental unit (EU) and fixed effect of treatment. Minutes ruminating was analyzed as an analysis of covariance with individual animal as the EU, fixed effects of treatment, days on feed (DOF) and their interaction, and baseline minutes ruminating as a covariate in the model. Liver abscess prevalence, rumen health, and categorical carcass data were analyzed with the Fisher's exact test to determine differences between treatments. No difference (P ≥ 0.19) was observed for final SBW, average daily gain, dry matter intake, feed conversion efficiency, dressing percentage, hot carcass weight, calculated yield grade, marbling score, 12th rib fat thickness, calculated empty body fat, observed dietary NE for maintenance and gain, observed-to-expected dietary NE for maintenance and gain, or distribution of liver abscess prevalence, ruminitis score, or USDA yield grade. Ribeye area tended (P = 0.10) to differ between treatments with 12R steers exhibiting a 3.5% larger ribeye. Distribution of USDA quality grade differed (P = 0.003) between treatments with 12R steers having 25% more carcasses grading USDA average choice or better. A treatment × DOF interaction (P = 0.045) was observed for minutes ruminating per day. Daily minutes ruminating was increased (P ≤ 0.05) for 12R on d 1, 2, and 20 and tended to be increased (P ≤ 0.10) for 12R on days 10, 13, 24, and 25. Inclusion of an additional 5% RE to finishing cattle diets during a 28 d RH feeding period can be a management strategy to decrease risk of digestive upsets without sacrificing growth performance or carcass quality. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of CaMg(CO3)2 (MIN-AD, Papillon Agricultural Company, Easton, MD; MA) and/or tylosin phosphate (Tylan, Elanco, Indianapolis, IN; TY) supplementation on growth performance of yearling beef steers during transition to a finishing diet during the first 28 days on feed. Treatments were arranged in a 2 × 2 factorial arrangement including MA and TY. Beef steers (n = 156; initial BW = 469 ± 18.0 kg) were randomly assigned to dietary treatments pens (7 to 8 steers/pen) with pen (n = 20 pens total, 10 pens/main effect mean, and 5 pens/simple effect mean) serving as the experimental unit. Cattle were transitioned from a 30 % roughage receiving diet to a 7 % roughage finishing diet based on dry-rolled corn, dried distillers grains plus solubles, a liquid supplement, and oat silage over the initial 20 d period. Monensin sodium was included in the diet at 30 mg/kg (DM basis). The MA was included at 1.5 % of the diet (DM basis) in replacement of dry-rolled corn and TY was provided at 90 mg/animal·d-1. Data were analyzed according to a randomized complete block design with the fixed effects of MA, TY, or their interaction; block was considered a random effect. No interaction was noted between MA or TY (P ≥ 0.68) for any variables measured. The main effect of TY did not influence d 28 BW, ADG, DMI, or G:F (P ≥ 0.43). The main effect of MA reduced DMI by 1.9 % (P = 0.01), but did not appreciably influence d 28 BW, ADG, or G:F (P ≥ 0.42). MA may decrease DMI while maintaining similar BW gain and efficiency compared with non-supplemented calves. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of orally administered Megasphaera elsdenii NCIMB 41125 (ME) in preconditioned calves abruptly transitioned from a receiving diet with 4% dietary starch [dry matter (DM) basis] to a growing diet with 37% dietary starch (DM basis). Preconditioned steers [n = 192; initial shrunk body weight (SBW) = 309 kg ± 20.6 kg] were assigned to microbial supplement treatment in a randomized complete block design. Treatments were CON: no ME; and LP: orally administered 20 mL of microbial supplement (2 × 1010 colony forming units ME/mL) immediately before diet change. Steers were abruptly changed from a receiving diet based upon soybean hulls and wheatlage with 4% dietary starch (DM basis) to a growing diet based upon high-moisture ear corn, dry-rolled corn, and wheatlage with 37% dietary starch (DM basis). Diets were switched on an equal DM basis to achieve abrupt change and steers were fed treatment diet for 49 d until study completion. Prior to study initiation, steers (n = 72; n = 3/pen) were fitted with wireless rumination tags to track daily activity and rumination time. Growth performance data and efficiency of dietary net energy utilization were analyzed with pen as the experimental unit, fixed effect of treatment, and random effect of block (location in the feedlot). Activity and rumination data were analyzed in a repeated measures analysis of covariance with individual animal as experimental unit, fixed effects of treatment, week, and their interaction, block (location in feedlot) as a random effect, and baseline activity and rumination as a covariate in the model. If no interaction was observed, main effect means of treatment and week were evaluated independently. For all statistical analysis, P ≤ 0.05 was declared significant and P ≤ 0.10 was declared a tendency. No difference (P ≥ 0.20) was observed between treatments for final SBW, average daily gain, dry matter intake, feed efficiency, calculated net energy (NE) for maintenance and gain or observed-to-expected ratio of NE for maintenance and gain. Additionally, no treatment × day differences (P ≥ 0.27) were observed for activity or rumination measures. Treatment effects (P < 0.01) were observed for both activity and rumination where LP steers had a 2% increase and 2% decrease in minutes per day active and ruminating respectively. Additionally, a positive linear effect (P < 0.01) of week was observed for minutes ruminating and quadratic effects (P < 0.01) of week were observed for minutes active and ruminating. Oral administration of ME had no effects on growth performance or efficiency of dietary net energy utilization in steers transitioned from a receiving diet containing 4% starch (DM basis) to a growing diet containing 37% starch (DM basis). [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of kernel processing of corn silage on apparent total tract digestibility (ATTD) of steers fed corn silage included at 65% of the diet (DM basis). Steers (n = 184; initial shrunk BW = 338 ± 22.3 kg) were assigned to 1 of 24 pens (8 steers/pen). Pens were randomly assigned to one of two dietary treatments (12 pens/treatment): non-kernel processed corn silage included at 65% diet DM (CON) or kernel processed corn silage included at 65% diet DM (KPCS) in a randomized complete block design with pen as experimental unit. Steers from replicates 1 to 8 spent 47-d on test and steers from replicates 9 to 12 were fed for 46-d on test. On the final day of the study, apparent total tract digestibility of diet dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), N, and starch was determined using an internal marker ratio technique using the undigested NDF residue following a 240 h in-situ incubation in ruminal fluid (uNDF240). Diet samples were collected twice daily (morning and afternoon) starting two days prior to fecal collections. Fecal collections were taken via rectal palpation on the final day of the study. Data were analyzed as a RCBD with fixed effects of KPCS diet and random effect of block (location within feedyard). Kernel processing increased DMI by 6% (P = 0.01) during the collection period and cumulative DMI throughout the study was increased by 2% for KPCS treatment (P = 0.04). Kernel processing did not enhance the ATTD of DM, OM, or starch (P = 0.71), but did decrease ATTD of NDF by approximately 6% (P = 0.04) compared with corn silage that was not kernel processed. Furthermore, kernel processing was determined to increase ATTD of N by 5% (P = 0.05). These results indicate that kernel processed corn silage may decrease apparent total tract digestibility of neutral detergent fiber due to greater intake but does not appreciably influence starch digestibility. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to determine if electrolyte application (glycerol-based electrolyte solution containing potassium chloride, acetic acid, magnesium hydroxide, sodium propionate, and sodium chloride; 5.10% potassium, 1.00% sodium, and 0.87% magnesium; HydraFit--Micronutrients USA LLC, Indianapolis IN) before shipping for harvest increased cold carcass weight in beef steers. Steers (n = 40; 20 steers per treatment; BW = 659 ± 72.9 kg) were weighed 40 h before harvest, blocked by BW (n = 4 BW blocks), and assigned to one of two treatments: no HydraFit (Con) or HydraFit (HF) added to the water at 4% vol/vol (4 pens/treatment, 8 pens total). Feed and water access was not restricted nor was a shrink percentage applied to any BW measures. Thirty-six hours before harvest a 378 L water tank was filled with water from the same source the steers had been consuming since arrival. Water and feed were introduced at 36 h before harvest. Final BW was captured immediately before shipping (12 h prior to harvest). Cattle were transported 98 km to a commercial abattoir. Cattle were held in lairage with ad libitum access to water before harvest the following morning. Water intake pre-shipment was determined after the cattle were removed from the pens and transported to slaughter. Water volume was estimated by measuring water depth remaining in the tank. Depth measurements were calibrated to water volume by metering (DM-P; Assured Automation, Roselle, NJ; ± 1.0%) 0.64 cm of water into each tank and recording the liters of water metered. Hot carcass weight was determined at the time of slaughter and cold carcass data was determined after a 48-hour chill. One steer from Con was condemned at the abattoir for reasons unrelated to treatment, consequently, the contribution of this steer to the pen mean was deleted. Providing HF in the drinking water for approximately 22 hours before shipping for harvest tended to increase final body weight (P = 0.08) by 1% but had no effect (P = 0.88) on hot or cold carcass weight. In conclusion, providing a glycerol-based electrolyte solution to finished beef cattle for approximately 22 hours before shipping for harvest tended to improve final body weight. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of CaMg(CO3)2 (MIN-AD, Papillon Agricultural Company, Easton, MD; MA) and or tylosin phosphate (Tylan, Elanco, Indianapolis, IN; TY) supplementation on 24-hour behavior and rumination activity of yearling beef steers fed a finishing diet. A 2 × 2 factorial arrangement of treatments was used resulting in 4 dietary treatments: no MA and no TY (-MA/-TY), MA and no TY (MA/-TY), no MA and TY (-MA/TY), or MA and TY (MA/TY). Beef steers (n = 158; 469 ± 18.0 kg) were randomly assigned to dietary treatments with pen (n = 20 pens total, 10 pens/main effect mean, and 5 pens/simple effect mean) serving as the experimental unit. The MA was included at 1.5% of the diet (DM basis) in replacement of dryrolled corn and TY was provided at 90 mg·animal-1·d-1. Observation began at 0800 h and ended at 0750 h the following day, resulting in a 24-hour observation period. Observations were recorded on a pen basis, with number of animals/type of activity recorded every 10 minutes on d 42 on feed (22 d on finisher). Activity categories included number of animals drinking (DR), eating (EA), active (standing; AC), ruminating (RU), and resting (RE) per pen. Chewing (CHE) was determined as the sum of eating and ruminating activity. Data were analyzed as a randomized complete block design with the fixed effects of MA, TY, and their interaction; block (pen location) was considered a random effect. An interaction was noted between MA and TY for time spent drinking (P = 0.03) and ruminating (P = 0.01). Steers from -MA/TY spent more time drinking compared with the -MA/-TY and MA/TY steers; steers from MA/-TY were intermediate (P < 0.10). Steers from -MA/-TY ruminated 28% longer compared with MA/-TY steers (P = 0.05) and 20% longer than -MA/TY (P = 0.05), steers from MA/TY ruminated 16% longer than steers from MA/-TY (P = 0.05), while steers from -MA/TY were intermediate (P > 0.10). The main effect of MA tended to increase time spent eating by 19.3% (P = 0.06); however, no differences (P = 0.28) were noted for the main effects of MA or TY for minutes/day spent chewing, resting, or active. These results indicate that supplementation of MA may alter feeding behavior, resulting in increased minutes/day spent eating. In addition, supplementation of TY and MA may result in increased water intake, and alter time spent ruminating per day. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the influence that a rumen-protected B-vitamin (RPBV) blend (containing pantothenic acid, pyridoxine, folic acid, biotin, and cyanocobalamin; Vivalto, Trouw Nutrition, Isola Vicentina, Italy) had on growth performance, efficiency of dietary net energy utilization, carcass trait responses, and liver abscess severity and prevalence in beef steers fed a finishing diet. Steers (n = 246; initial shrunk body weight (BW) = 411 ± 25.8 kg) from two sources, were used in a 126-d randomized complete block design experiment. Within 48 h after arrival, steers were individually weighed and allotted to one of 24 pens (n = 10 to 12 steers; 8 pens/treatment) and randomly assigned to 1 of 3 treatments: 1) No RPBV; 2) RPBV1 at 1 g/hd/d; 3) RPBV2 at 2 g·animal-1·d-1/. During the first 14 d cattle received two transition diets. From d 15 to d 126 cattle were fed the final diet containing 53% dry-rolled corn; 23% corn silage; 20% MDGS; and 4% suspended supplement. Data were analyzed using the GLIMMIX procedure of SAS 9.4 with treatment as the fixed effect and block (Pen location) as the random effect; pen was considered the experimental unit. No differences (P ≥ 0.13) were found for dry matter intake, final live BW, average daily gain (ADG), or feed efficiency (G:F) among treatments. Carcass-adjusted final BW, ADG, and G:F were not influenced by treatment (P ≥ 0.59). Hot carcass weight, dressing percentage, marbling score, kidney-pelvicheart fat, or BW at 28% empty body fat did not differ among treatments (P ≥ 0.11). Rib eye area (REA) was altered (quadratic effect, P = 0.02) by treatment; steers from RPBV 1g had decreased REA compared with others. Additionally, calculated yield grade (YG) and calculated retail yield (RY) were altered (quadratic effect, P = 0.01) by treatment; steers from RPBV 1 g had increased YG and decreased RY compared with others. Estimated empty body fatness tended (P = 0.06) to be greater from steers fed RPBV compared with control. Overall USDA YG distribution was altered by dietary treatment (P = 0.01). The proportions of YG1 and YG5 carcasses were unaffected by treatment, but there was a shift in the proportion of carcasses that graded YG2, YG3, and YG4 among treatments. Distribution of USDA Quality Grade was not altered by treatment (P = 0.53). No differences were observed on liver abscesses among treatments. The use of RPBV altered carcass muscularity and rib fat accumulation which impacted the overall YG distribution. However, RPBV did not appreciably influence any cumulative growth performance measures liver abscess incidence or severity. [ABSTRACT FROM AUTHOR]

The objective of the study was to determine the influence that initial BW has on growth performance responses, efficiency of dietary net energy (NE) utilization, and carcass traits in feedlot steers. Crossbred Charolais steers from a single source, (n = 70; initial BW = 329 ± 72.6 kg) were used in feedlot experiment at the Ruminant Nutrition Center, in Brookings, SD, during a 209-day growing-finishing period. These steers represented the lightest and heaviest proportions of steers taken from a larger group of 265 steer calves. On d 0 and d 1 BW and hip height (HH) measurements were collected for allotment proposes, and the initial experimental BW was the average between d 0 and d 1 BW. Steers were allocated to 1 of 2 treatments: 1) lighter (276 ± 16 kg; LIW) or 2) heavier (356 ± 16 kg; HIW) initial BW and allotted to 10 pens (n = 7 steers/pen; 5 pens/treatment). Steers were fed a diet containing 16% roughage once daily. Data were analyzed as a randomized complete block design with pen as the experimental unit. Treatment was included as a fixed effect and block (location) was considered a random effect in the statistical model. The LIW steers had a greater cumulative HH change compared with HIW. Final BW and carcass-adjusted (HCW/0.625) BW were greater for HIW steers by 13.1% and 13.4% respectively (P = 0.01). The HIW steers had a 14.4% greater DMI (P = 0.01) compared with LIW. Cumulative ADG was greater for HIW by 3% (P = 0.04). LIW steers had improved feed conversion (P = 0.01) by 11.3% compared with HIW. The HIW steers had greater (P < 0.05) HCW (15.5%), marbling scores (6.8%), and Yield grade (16.0%), and decreased REA/HCW (P = 0.01) by 5.9% compared with LIW. Steers from HIW tended to have greater rib fat (P = 0.09) by 15% compared with LIW. The distribution of USDA Yield grade was altered by initial BW (P = 0.04) with a shift in proportions of steers with greater numerical Yield grades for steers in HIW compared with LIW. No differences were detected (P = 0.22) for the distribution of Quality grade or liver abscess prevalence and severity. In conclusion, HIW steers had greater growth, but poorer feed efficiency compared with LIW steers. Steers with a HIW produced fatter carcasses with a greater amount of marbling. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine if supplementing encapsulated butyric acid and zinc (BZ) in lambs abruptly transitioned to a finishing diet has effects on growth performance, efficiency of dietary net energy utilization, and carcass traits following a 59.5 d finishing period. Polypay wethers (n = 32; initial shrunk BW = 39 kg ± 4.8 kg) were grouped by initial shrunk BW and assigned to dietary treatment (CON: 0 g BZ/kg diet DM; BZ: 2 g BZ/kg diet DM) in a randomized complete block design (RCBD) with pen (n = 16) as experimental unit. Wethers were abruptly transitioned from growing diet (based upon grass hay, dried distillers grains plus solubles, and a soybean meal based pellet; 1.65 Mcal/kg NEm, 0.95 Mcal/kg NEg) to finishing diet (based upon whole corn, soybean hulls, and a soybean meal pellet; 2.02 Mcal/kg NEm, 1.33 Mcal/kg NEg) upon study initiation. Lambs were harvested at the South Dakota State University meat lab and empty body measures and carcass traits were recorded. Growth performance was calculated on a shrunk live basis (BW × 0.96). Data were analyzed as an RCBD with fixed effect of treatment and random effect of block. No differences (P = 0.15) were observed for final shrunk BW, ADG, DMI, feed conversion efficiency, observed-to-expected (O:E) DMI, O:E NEm, O:E NEg, EBW, dressed yield, or HCW. Percentage of boneless closely trimmed retail cuts (BCTRC) and red meat yield (RMY) were decreased (P = 0.03) for BZ vs. CON. Body wall thickness was increased (P = 0.02) for BZ vs. CON. Supplementing wethers BZ during an abrupt transition to a finishing diet had no effects on growth performance, efficiency of dietary net energy, or empty body measures and had minor effects on body wall thickness, percentage BCTRC, and RMY. [ABSTRACT FROM AUTHOR]