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Simple Summary: Phenolic compounds, and sources rich in these secondary metabolites, have received great interest in the monogastric nutrition area and have been considered natural alternatives to the use of synthetic growth promoters in intensive swine production. The present study evaluated physiological variables, productive performance, and carcass quality of finishing pigs supplemented with ferulic acid (FA) and grape pomace meal (GPM) for 31 days prior to slaughter under heat stress conditions. The inclusion of FA and GPM in the diet did not affect any of the physiological variables evaluated. On the contrary, GPM increased the feed intake (FI), while the FA addition modified hot and cold carcass yields. Likewise, GPM decreased the marbling degree of the carcasses. The results indicate that the combined supplementation of FA and GPM is favorable for carcass characteristics. The effect of individual and combined supplementation of FA and GPM on physiological variables, productive performance, and carcass characteristics of finishing pigs under heat stress conditions were investigated. Forty Yorkshire × Duroc pigs (80.23 kg) were individually housed and randomly distributed into 4 groups under a 2 × 2 factorial arrangement (n = 10): Control (basal diet, BD); FA, BD + 25 mg FA; GPM, BD with 2.5% GPM; and MIX, BD with 25 mg FA and 2.5% GPM. Additives were supplemented for 31 days. The inclusion of FA or GPM did not modify rectal temperature and respiratory rate. There was an effect of the interaction on FI, which increased when only GPM was supplemented, with respect to Control and MIX (p < 0.05). Average daily gain (ADG) and feed conversion (FC) were not affected by treatments (p > 0.05). The inclusion of FA improved hot and cold carcass weight, while the addition of GPM decreased the marbling (p < 0.05) and tended to increase loin area (p < 0.10). GPM increased liver weight (p < 0.05). The addition of GPM and FA can improve some carcass characteristics under heat stress conditions. It is necessary to continue investigating different levels of inclusion of GPM and FA in finishing pigs' diets. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effect of ferulic acid (FA) and clinoptilolite (CTL) supplementation on the growth performance, carcass characteristics, and meat quality of hair-breed lambs. Twenty-eight Kathadin male lambs (33.72 ± 3.4 kg) were randomly allocated to one of the four diets (n=7) under a 2 × 2 factorial arrangement to evaluate the effect of FA (0 or 300 ppm) and CTL (0% or 1%) during the last 40 days of the finishing phase. No interaction between additives was shown for growth performance, carcass characteristics and meat quality, with exception of the fatty acid profile (p < 0.05). FA reduced feed intake and carcass conformation (p < 0.05). Wholesale cuts were not affected by FA or CTL (p > 0.05). The L*, a*, and C* color parameters and some intramuscular fatty acids of the longissimus thoracis muscle were positively modified by CTL supplementation (p < 0.05). While there was no FA × CTL interaction, each additive could be used individually in animal nutrition to improve the feedlot performance and meat quality of the lambs.

Our objective was to compare intake, gain, and feed efficiency of steers fed rumen protected lysine and/or methionine in 10% crude protein diet relative to performance of steers fed a diet with 13% crude protein without added amino acids. Beef steers [n = 161; body weight (BW) = 429.7 ± 44.5kg] were used in this experiment. Calves were randomly assigned to treatments consisting of 1) positive control diet (POS), formulated to contain 13.0 to 13.5% CP, 2) negative control (NEG) diet containing 10.2% CP, which also forms the basal diet for the remaining treatments, 3) rumen protected methionine (RPMet) 10.2% CP basal diet and 7.2 g/d supplemental methionine, 4) rumen protected lysine (RPLys) 10.2% CP basal diet and 18.5 g/d supplemental lysine, and 5) the combination of rumen protected lysine and methionine (RPMet+Lys) 10.2% basal diet with 7.2 and 18.5 g/d supplemental methionine and lysine, respectively. Initial and final BW were unaffected by treatment (P ≥ 0.24). Average daily gain for POS (1.93 kg/d P ≤ 0.02) was greater than those of NEG, RPLYS, and RPMET+LYS, but was similar to RPMET (1.86 kg/d; P = 0.17). Dry matter intake was greater in RPMET (12.1kg/d; P ≤ 0.10) compared with all other treatments. Gain-to-feed ratio was greatest in POS (0.170 kg gain:kg DMI; P ≤ 0.04). The impacts of rumen-protected amino acids on performance (intake, gain, and efficiency) of beef steers fed high-concentrate diets were inconsistent. Evaluating both lysine and methionine supplied independent of each other in various concentrations is critical before moving forward with recommendations for beef cattle. USDA is an equal opportunity provider and employer. [ABSTRACT FROM AUTHOR]

The effect of individual and combined supplementation of FA and GPM on physiological variables, productive performance, and carcass characteristics of finishing pigs under heat stress conditions were investigated. Forty Yorkshire × Duroc pigs (80.23 kg) were individually housed and randomly distributed into 4 groups under a 2 × 2 factorial arrangement (n = 10): Control (basal diet, BD); FA, BD + 25 mg FA; GPM, BD with 2.5% GPM; and MIX, BD with 25 mg FA and 2.5% GPM. Additives were supplemented for 31 days. The inclusion of FA or GPM did not modify rectal temperature and respiratory rate. There was an effect of the interaction on FI, which increased when only GPM was supplemented, with respect to Control and MIX (p < 0.05). Average daily gain (ADG) and feed conversion (FC) were not affected by treatments (p > 0.05). The inclusion of FA improved hot and cold carcass weight, while the addition of GPM decreased the marbling (p < 0.05) and tended to increase loin area (p < 0.10). GPM increased liver weight (p < 0.05). The addition of GPM and FA can improve some carcass characteristics under heat stress conditions. It is necessary to continue investigating different levels of inclusion of GPM and FA in finishing pigs’ diets.

Simple Summary: We previously showed that feeding selenium-enriched alfalfa hay to weaned beef calves diversified the nasal microbiome and improved health and growth in the feedlot, resulting in greater carcass weight and quality at slaughter. The objective of the current study was to see whether selenium supplementation of dams during various pregnancy trimesters similarly improves health and performance. Maternal supranutritional selenium supplementation during pregnancy increases selenium concentrations in calves, but is more effective the shorter the time period between maternal supplementation and assessment. Thus, calves should be fed selenium-enriched forages again at weaning in order to see a benefit in the nasal microbiome abundance and diversity, and consequently, in carcass measurements at slaughter. We previously reported that feeding Se-biofortified alfalfa hay to weaned beef calves in a preconditioning program increases whole-blood Se (WB-Se) concentrations and nasal microbiome abundance and diversity during the preconditioning period, decreases morbidity and mortality during the feedlot period, and increases carcass weight and quality at slaughter. The objective of the current study was to see whether similar improvements can be achieved through Se supplementation of dams during various pregnancy trimesters. In a two-year experimental study, 80 Angus-cross cows received once-weekly Se-yeast boluses containing 105 mg of Se, during either the first (TR-1), second (TR-2), or third (TR-3) pregnancy trimester, or were not bolused (CTR). Whole-blood Se concentrations were higher from CTR, to TR-1, to TR-2, and to TR-3 in newborn calves (all p < 0.01). At weaning, only calves from TR-3 mothers had higher WB-Se concentrations compared with calves from CTR mothers (p = 0.02), and no significant differences in nasal microbiome abundance and diversity or nasal microbiota were observed. In the feedlot period, morbidity was low, and no differences were observed. At slaughter, no differences in carcass weight and quality were observed. In conclusion, Se supplementation of pregnant cows is effective for increasing WB-Se concentration of newborn calves, and the increase can be sustained until weaning for calves born to TR-3 dams. However, the increase in WB-Se concentrations is small and does not result in beneficial changes in the nasal microbiome. Thus, calves should be fed Se-biofortified forages again at weaning in a preconditioning program in order to diversify the nasal microbiome prior to entering the feedlot. [ABSTRACT FROM AUTHOR]

Context. Genomic-based technologies are allowing commercial beef producers to predict the genetic merit of individual animals of unknown pedigree with increased ease and accuracy. Genomic selection tools that can accurately predict the feedlot and carcass performance of steers have the potential to improve profitability for the beef supply chain. Aims. To validate the ability of the Angus SteerSELECT genomic product to predict differences in performance of Australian Angus steers, in terms of carcass weight, marbling score, ossification score and carcass value, using a short-fed (100 days) or long-fed (270 days) finishing protocol at a commercial feedlot. Methods. A reference population of 2763 Australian Angus steers was used to generate genomic prediction equations for three carcass traits, namely, carcass weight, marbling score and ossification. The accuracy and bias of genomic predictions of breeding values were then evaluated using a validation population of 522 Angus steers, either short- or long-fed at a commercial feedlot, by comparing breeding values to measured phenotypes. The potential economic benefits for feedlot operators when using Angus SteerSELECT were estimated on the basis of the ability of the tool to predict the carcass value of steers in the validation population. Key results. The accuracy of genomic predictions of breeding values for carcass weight, marbling score and ossification score were 0.752, 0.723 and 0.734 respectively. When steers were ranked in quartiles for predicted carcass value, calculated using genomic predictions of breeding values for carcass weight and marbling score, the least-square mean carcass value for steers in each quartile, from bottom 25% predicted performers to top 25% predicted performers, were estimated at A$1794, A$1977, A$2021 and A$2148 for short-fed steers and A$3546, A$3780, A$3864 and A $4258 for long-fed steers. Differences in the carcass value least-squares mean between the bottom and top quartile were highly significant (P < 0.001) for both short-fed and long-fed steers. Conclusions. Genomic prediction equations used in Angus SteerSELECT can predict differences in carcass weight, marbling score, ossification score and carcass value in both short-fed and long-fed Australian Angus steers. Implications. Genomic selection tools that can predict differences in performance, in terms of growth and carcass characteristics, of commercial feedlot cattle have the potential to significantly increase profitability for the beef supply chain by improving the quality and consistency of the beef products they produce. [ABSTRACT FROM AUTHOR]

This research analyzed how maternal plane of nutrition during mid-gestation impacts growth, blood metabolites, expression of microRNA and messenger RNA in skeletal muscle, feedlot performance, and carcass characteristics of progeny. Thirty-two cows were bred to the same Angus sire and fed to either maintain a body condition score (BCS) of 5.0 to 5.5 (maintenance [MAIN]; n = 15) or to lose 1 BCS (restriction [REST]; n = 17) over an 84-d period of mid-gestation. Following the second trimester, all cows were co-mingled and fed at maintenance for the remainder of gestation. Following the 84-d treatment period, REST cows had a lower (P < 0.01) BCS than MAIN cows. At the end of the third trimester, there was no difference (P = 0.78) in BCS between the treatment groups. There was no difference (P > 0.10) between offspring in birthweight, weaning weight, average daily gain, feed efficiency, dry matter intake, carcass yield, steak quality, or in circulating levels of glucose, cortisol, insulin, or insulin-like growth factor-1. REST offspring expressed more (P < 0.05) miR-133a, miR-133b, miR-181d, miR-214, miR-424 and miR-486 at weaning than MAIN offspring. At harvest, REST offspring expressed more (P < 0.05) miR-133a and less (P < 0.01) miR-486 than MAIN offspring. REST steaks were perceived as more tender (P = 0.05) by a trained sensory panel. These results indicate that maternal nutrient restriction during mid-gestation resulting in a loss of 1 BCS has an effect on microRNA expression in the skeletal muscle but does not alter postnatal growth potential, carcass quality, or end product quality of the offspring. This suggests that moderate restriction in maternal nutrition during the second trimester, which results in a drop in BCS that can be recovered during the third trimester, should not cause alarm for producers when considering future offspring performance.

We previously reported that feeding Se-biofortified alfalfa hay to weaned beef calves in a preconditioning program increases whole-blood Se (WB-Se) concentrations and nasal microbiome abundance and diversity during the preconditioning period, decreases morbidity and mortality during the feedlot period, and increases carcass weight and quality at slaughter. The objective of the current study was to see whether similar improvements can be achieved through Se supplementation of dams during various pregnancy trimesters. In a two-year experimental study, 80 Angus-cross cows received once-weekly Se-yeast boluses containing 105 mg of Se, during either the first (TR-1), second (TR-2), or third (TR-3) pregnancy trimester, or were not bolused (CTR). Whole-blood Se concentrations were higher from CTR, to TR-1, to TR-2, and to TR-3 in newborn calves (all p < 0.01). At weaning, only calves from TR-3 mothers had higher WB-Se concentrations compared with calves from CTR mothers (p = 0.02), and no significant differences in nasal microbiome abundance and diversity or nasal microbiota were observed. In the feedlot period, morbidity was low, and no differences were observed. At slaughter, no differences in carcass weight and quality were observed. In conclusion, Se supplementation of pregnant cows is effective for increasing WB-Se concentration of newborn calves, and the increase can be sustained until weaning for calves born to TR-3 dams. However, the increase in WB-Se concentrations is small and does not result in beneficial changes in the nasal microbiome. Thus, calves should be fed Se-biofortified forages again at weaning in a preconditioning program in order to diversify the nasal microbiome prior to entering the feedlot.

Lubabegron (Experior; Elanco, Greenfield, IN, USA) is the first U.S. Food and Drug Administration approved feed additive for reducing gas emissions from feedlot animals or their waste; it does not have live or carcass performance claims. Our primary objective was to determine the effect of lubabegron on feedlot performance and carcass traits in finishing beef steers compared to ractopamine hydrochloride (Optaflexx; Elanco, Greenfield, IN, USA). A commercial feedlot trial using cross-bred beef steers ( n  = 2,117; 373 ± 15 kg initial body weight [BW]) was completed with a randomized complete block design. Treatments consisted of two feed additives: (1) OPT targeted to deliver 300 mg/animal/d of ractopamine hydrochloride for 28 ± 7 d out from harvest and (2) EXP targeted to deliver 36 mg/animal/d of lubabegron 56 ± 7 d out from harvest and a 4-d preslaughter withdrawal period. Twenty 70 to 142 hd pens with 10 pens per treatment were used. Cattle were weighed at arrival processing and at harvest and fed for an average of 167 d. Data were used to calculate production metrics, partial budgets, and estimated greenhouse gas emissions using published methods, and were analyzed using linear mixed models with pen as the experimental unit and block as a random intercept. A statistical significance threshold of α  = 0.05 was determined a priori. There was no evidence for statistically significant differences between treatments for initial BW ( P  = 0.70), health-related outcomes ( P values ≥ 0.43), or mobility scores (P  = 0.09). Cattle-fed EXP had increased final BW, ADG, G:F, and decreased dry matter intake ( P values ≤ 0.01) compared to OPT. Carcasses were 11 ± 1.76 kg (hot carcass weight) heavier in EXP group ( P  < 0.01), and differed between treatments for both yield grades (YG) and quality grades distributions (P values ≤ 0.01). Cattle-fed EXP had a shift toward more YG 1 and 2, select and sub-select carcasses compared to OPT, which had as shift toward more YG 3, 4, 5, prime and choice carcasses. With increased beef production and efficiency compared to OPT, the estimated CO 2 equivalent emissions from production were reduced by 6.2% per unit of carcass weight for EXP ( P  ≤ 0.01). Estimated net returns/animal shipped were $56.61 ± 9.37 more for EXP than OPT ( P  ≤ 0.01). In conclusion, when cattle were fed for the same total number of days, feeding EXP compared to OPT increased net returns, feedlot performance, and efficiency, but resulted in carcass yield and quality characteristics that may impact marketing programs., Competing Interests: One author (NB) is an employee of Elanco Animal Health, but he had no role in the design or implementation of the study; he calculated estimated emissions for de-identified lots (i.e., was masked to treatments). Other authors (DR, BD) have previously received funding from Elanco Animal Health for research or consulting work., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)

This study investigated the impacts of metabolizable protein (MP) restriction in primiparous heifers during mid- and/or late-gestation on progeny performance and carcass characteristics. Heifers were allocated to 12 pens in a randomized complete block design. The factorial treatment structure included two stages of gestation (mid- and late-) and two levels of dietary protein (control (CON); ~101% of MP requirements and restricted (RES); ~80% of MP requirements). Half of the pens on each treatment were randomly reassigned to the other treatment at the end of mid-gestation. Progeny were finished in a GrowSafe feeding system and carcass measurements were collected. Gestation treatment x time interactions indicated that MP restriction negatively influenced heifer body weight (BW), body condition score, and longissimus muscle (LM) area (p < 0.05), but not fat thickness (p > 0.05). Treatment did not affect the feeding period, initial or final BW, dry matter intake, or average daily gain of progeny (p > 0.05). The progeny of dams on the RES treatment in late gestation had a greater LM area (p = 0.04), but not when adjusted on a hot carcass weight basis (p > 0.10). Minimal differences in the animal performance and carcass characteristics suggest that the level of MP restriction imposed during mid- and late-gestation in this study did not have a significant developmental programming effect.

Feeding dried distillers grains with solubles (DDGS), a feed high in fat and protein, to lactating beef cows can alter milk production and composition, resulting in improved pre-weaning growth of progeny. This alteration in milk profile may consequently alter the growth and carcass composition of the offspring after weaning. Therefore, Angus×Simmental steers (n=48) whose dams were fed one of two diets supplemented with either DDGS or soybean meal (CON) from calving to mid-lactation were placed in a feedlot to determine the effects of maternal nutrition during lactation on progeny development and carcass composition. Cow–calf pairs were allotted to two treatments at birth based on cow and calf BW, breed and age. Maternal diets were isocaloric (3.97 MJ/kg NEg) and consisted of rye hay supplemented with DDGS at 1% of BW (19.4% CP; 8.76% fat) or rye hay and corn silage supplemented with CON (11.7% CP; 2.06% fat). After conclusion of the treatments at 129 days postpartum, cow–calf pairs were comingled and managed as one group until weaning at 219 days postpartum. Steers were then transitioned to a common diet composed of 60% DDGS, 34% corn silage and 6% vitamin/mineral supplement and were placed indoors in individual pens with slatted floors. An intravenous glucose tolerance test (IVGTT) was performed 134 days after feedlot entry on 16 steers (CON, n=7; DDGS, n=9) to determine the effect of maternal diet on glucose and insulin sensitivity. Steers were slaughtered at a target BW of 645 kg. Categorical and continuous data were analyzed using the GLIMMIX and MIXED procedures of SAS, respectively. Steers from DDGS dams tended to be heavier on day 85 of feedlot finishing (P=0.09) compared with steers from CON dams. However, there were no differences in final weight, average daily gain, dry matter intake or efficiency (gain:feed, P⩾0.18). Maternal treatments did not affect progeny days on feed (P=0.15), despite a mean difference of 9 days in favor of DDGS. Glucose and insulin concentrations and area under the curve of progeny as measured by IVGTT were not affected by maternal diet (P⩾0.16). Maternal DDGS supplementation decreased marbling score (P=0.04), but did not influence carcass grading percentage or any other carcass characteristic (P⩾0.17).

Growth-promoting technologies such as implants, ionophores, and β-agonists improve feedlot performance, efficiency, and carcass characteristics of cattle. The objective of this experiment was to determine the effects of dose and duration of ractopamine hydrochloride (RH) on feedlot performance and carcass characteristics when fed to Holstein steers. A randomized complete block design was used with a 3 × 3 factorial arrangement of treatments with 3 RH doses (0, 300, or 400 mg∙steer−1∙d−1) fed for 3 durations (28, 35, or 42 d). Holstein steers (n = 855; initial body weight [BW] = 448 ± 37 kg) were blocked by BW and randomly allocated to 1 of 9 pens (15 blocks; 9 dose × duration treatment combinations) approximately 72 d before harvest. Weekly pen weights, chute temperament scores, and animal mobility were determined during the RH feeding period. At harvest, carcass data were collected on all steers, and tenderness was measured on steaks from 3 or 4 randomly selected steers from each pen and slice shear force (SSF) was determined on one steak selected from each side of the carcass after aging for 14 or 21 d. For feedlot performance, carcass characteristics, and SSF, no dose × duration interactions were observed (P ≥ 0.11). With increasing RH dose, average daily gain (ADG) and gain-to-feed ratio (G:F) increased linearly (P ≤ 0.01), whereas BW gain increased linearly with RH dose and duration (P ≤ 0.01). Hot carcass weight (P = 0.02) and longissimus muscle (LM) area (P ≤ 0.01) increased linearly with increasing RH dose. The percentage of carcasses in the USDA Yield Grade 2 category increased linearly (P ≤ 0.01) and percentage of carcasses in the USDA Yield Grade 4 category tended (P = 0.08) to decrease linearly as RH dose increased. In the 14-d aged steaks, the percentage of steaks with SSF ≤ 15.3 kg decreased linearly (P ≤ 0.01), whereas the percentage of steaks with ≥20.0 kg SSF increased linearly (P ≤ 0.01) with increasing RH dose. After 21-d aging, there was a tendency (P = 0.06) for a greater percentage of steaks from steers fed RH to have SSF ≥ 20.0 kg (2% of total steaks), but no difference (P ≥ 0.12) in the percentage of steaks with SSF ≤ 19.9 kg. Final chute temperament (P ≥ 0.45) and animal mobility (P ≥ 0.67) scores were not affected by feeding RH. Increasing the dose of RH (300 or 400 mg∙steer−1∙d−1) fed for 28 to 42 d before harvest increased ADG, G:F, hot carcass weight, and LM area when fed to Holstein steers with no negative effects on behavior or mobility. The percentage of steaks classified as not tender improved when steaks were aged for 21 d from steers treated with RH. [ABSTRACT FROM AUTHOR]

Nelore is the most economically important cattle breed in Brazil, and the use of genetically improved animals has contributed to increased beef production efficiency. The Brazilian beef feedlot industry has grown considerably in the last decade, so the selection of animals with higher growth rates on feedlot has become quite important. Genomic selection (GS) could be used to reduce generation intervals and improve the rate of genetic gains. The aim of this study was to evaluate the prediction of genomic-estimated breeding values (GEBV) for average daily weight gain (ADG) in 718 feedlot-finished Nelore steers. Analyses of three Bayesian model specifications [Bayesian GBLUP (BGBLUP), BayesA, and BayesCπ] were performed with four genotype panels [Illumina BovineHD BeadChip, TagSNPs, and GeneSeek High- and Low-density indicus (HDi and LDi, respectively)]. Estimates of Pearson correlations, regression coefficients, and mean squared errors were used to assess accuracy and bias of predictions. Overall, the BayesCπ model resulted in less biased predictions. Accuracies ranged from 0.18 to 0.27, which are reasonable values given the heritability estimates (from 0.40 to 0.44) and sample size (568 animals in the training population). Furthermore, results from Bos taurus indicus panels were as informative as those from Illumina BovineHD, indicating that they could be used to implement GS at lower costs.

This study evaluated the effects of barley and corn finishing rations on feedlot performance and behavior of steers. Feedlot rations in this study were comprised of a main concentrate of either corn or barley. Steers were fed in a GrowSafe system to measure individual animal intake and behavior. Weight gain, average daily gain (ADG), and gain:feed were measured for each steer. Feeding behavior including time spent eating (min/day), visits per day, time per visit (min), eating rate (g/min), intake (kg/day), and intake per visit (g) were measured for each individual. Corn-fed steers had greater ADG (p < 0.01) and heavier hot carcass weights (HCW; p < 0.01). In addition, corn fed steers had a higher yield grade than barley fed steers (p < 0.01). No treatment effects (p ≥ 0.11) were observed for time spent eating, visits per day, time per visit, eating rate, intake g/kg body weight, or intake per visit. Although corn-fed steers had a greater ADG and HCW than barley-fed steers, they tended to consume more feed (p = 0.06). Depending on the difference of costs associated with feeding corn or barley, barley could be a potential high-quality feed source in beef cattle finishing rations.

Feedlot performance is reduced by heat stress and improved by β adrenergic agonists (βAA). However, the physiological mechanisms underlying these outcomes are not well characterized, and anecdotal reports suggest that βAA may confound the effects of heat stress on wellbeing. Thus, we sought to determine how heat stress and βAA affect growth, metabolic efficiency, and health indicators in lambs on a feedlot diet. Wethers (38.6 ± 1.9 kg) were housed under thermoneutral (controls; n = 25) or heat stress (n = 24) conditions for 21 d. In a 2 × 3 factorial, their diets contained no supplement (unsupplemented), ractopamine (β1AA), or zilpaterol (β2AA). Blood was collected on days −3, 3, 9, and 21. On day 22, lambs were harvested and ex vivo skeletal muscle glucose oxidation was determined to gauge metabolic efficiency. Feet and organ tissue damage was assessed by veterinary pathologists. Heat stress reduced (P < 0.05) feed intake by 21%, final bodyweight (BW) by 2.6 kg, and flexor digitorum superficialis (FDS) muscle mass by 5%. β2AA increased (P < 0.05) FDS mass/BW by 9% and average muscle fiber area by 13% compared with unsupplemented lambs. Blood lymphocytes and monocytes were greater (P < 0.05) in heat-stressed lambs, consistent with systemic inflammation. Plasma insulin was 22% greater (P < 0.05) and glucose/insulin was 16% less (P < 0.05) in heat-stressed lambs than controls. Blood plasma urea nitrogen was increased (P < 0.05) by heat stress on day 3 but reduced (P < 0.05) on days 9 and 21. Plasma lipase and lactate dehydrogenase were reduced (P < 0.05) by heat stress. Glucose oxidation was 17% less (P < 0.05) in muscle from heat-stressed lambs compared with controls and 15% greater (P < 0.05) for β2AA-supplemented compared with unsupplemented lambs. Environment and supplement interacted (P < 0.05) for rectal temperature, which was increased (P < 0.05) by heat stress on all days but more so (P < 0.05) in β2AA-supplemented lambs on days 4, 9, and 16. Heat stress increased (P < 0.05) the frequency of hoof wall overgrowth, but βAA did not produce any pathologies. We conclude that reduced performance in heat-stressed lambs was mediated by reduced feed intake, muscle growth, and metabolic efficiency. β2AA increased muscle growth and improved metabolic efficiency by increasing muscle glucose oxidation, but no such effects were observed with ractopamine. Finally, βAA supplementation was not detrimental to health indicators in this study, nor did it worsen the effects of heat stress. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify barley grain characteristics measured by laboratory procedures that could be used to predict barley energy content for finishing beef steers. Twenty-eight different barley genotypes were evaluated including 18 cultivars and 10 experimental lines. Laboratory analysis of barley samples included bulk density, particle size, N, ADF, starch, and ISDMD (in situ DM disappearance after 3 h of ruminal incubation). Animal performance data (BW, DMI, ADG, steer NEm, and NEg requirements) were collected from 26 feedlot experiments conducted in Montana and Idaho during a 10-yr period and were used to estimate barley NEm and NEg content. A total of 80 experimental units were available with each experimental unit being a diet mean from an individual feedlot experiment. Fifty-eight of the 80 experimental units were randomly selected and used in the development data set and the remaining 22 experimental units were used in the validation data set. Forward, backward, and stepwise selection methods were used to identify variables to be included in regression equations for NEm using PROC REG of SAS. Barley samples in the model development data set represented a wide range in concentrations (DM basis): N (1.6% to 2.8%), ISDMD (25.7% to 58.7%), ADF (3.6% to 8.0%), starch (44.1% to 62.4%), particle size (1,100 to 2,814 µm), and bulk density (50.8 to 69.4 kg/hL). The barley grain characteristics of particle size, ISDMD, starch, and ADF were the most important variables in six successful models (R 2 = 0.48 to 0.60; P = 0.001). The six prediction equations gave mean predicted values for NEm ranging from 1.99 to 2.05 Mcal/kg (average 2.04 Mcal/kg; 0.45% CV). The mean actual NEm values from animal performance trials ranged from 1.75 to 2.48 Mcal/kg (average 2.03 Mcal/kg; 6.5% CV). The mean bias or difference in predicted vs. actual values ranged from −0.001 to 0.005 Mcal/kg. Barley NEg values calculated from animal performance ranged from 1.13 to 1.78 Mcal/kg (average 1.39 Mcal/kg; 8.4% CV). Average predicted barley NEm and NEg were 0.02 and 0.01 Mcal/kg less, respectively, than the 2.06 Mcal/kg NEm and 1.40 Mcal/kg NEg reported by NRC. Barley NE can be predicted from simple laboratory procedures which will aid plant breeders developing new feed varieties and nutritionists formulating finishing rations for beef cattle. [ABSTRACT FROM AUTHOR]

Eighty-two yearling crossbred heifers (318.8 ± 1.03 kg) were utilized in a completely randomized design to evaluate the effects of distillers dried grains with solubles (DDGS) supplementation on animal performance, while grazing on rangeland of the Northern Great Plains, and subsequent feedlot performance, carcass characteristics, and meat quality traits. Treatments were: 1) 0% DDGS supplementation (CONT) and 2) 0.6% of body weight (BW) DDGS supplementation (SUP). Heifers received treatments for 70 d (6 June to 16 August) while grazing, and then were acclimated to and fed a common corn-based finishing diet for 109 d. Average daily gain (ADG) of SUP heifers was greater (P ≤ 0.01), resulting in heavier BW (P ≤ 0.03) following grazing compared with CONT heifers. Heifer performance, including ADG (1.91 ± 0.05 kg/d), gain to feed (G:F) (0.15 ± 0.003 kg), dry matter intake (DMI) (12.6 ± 0.20 kg), and final BW (572.4 ± 7.43 kg) were not different (P ≥ 0.13) during finishing. Hot carcass weight (335.7 ± 4.39 kg), Longissimus muscle area (81.30 ± 1.24 cm2), 12th rib fat thickness (1.24 ± 0.06 cm), and kidney, pelvic, heart fat (KPH) (1.85 ± 0.08%) were not different (P ≥ 0.47) between treatments. There were no differences (P ≥ 0.24) between treatments in yield grade (2.9 ± 0.10) or marbling (492 ± 22.3; Small00 = 400). Results from Warner–Bratzler shear force indicated that strip loin steaks from SUP heifers tended (P = 0.07) to have increased tenderness compared with strip loin steaks from CONT heifers (3.3 vs. 3.7 ± 0.12 kg, respectively). Inclusion of 0.6% BW supplementation during grazing increased (P = 0.01) strip loin steak muscle lightness (L*) compared with CONT steaks (46.5 vs. 45.5 ± 0.27, respectively). Strip loin steaks from heifers supplemented DDGS during grazing were perceived to be more tender by taste panelists (P = 0.02) than strip loin steaks from CONT heifers (5.9 vs. 5.5 ± 0.11; eight-point scale). Supplementation of DDGS during grazing improved ADG of yearling heifers with no effect on feedlot performance or carcass characteristics but did improve tenderness and steak sensory attributes. [ABSTRACT FROM AUTHOR]

Our objective was to determine the effects of dry and wet conditions during the preweaning on subsequent feedlot performance and carcass characteristics of beef cattle. Steers (n = 7,432) and heifers (n = 2,361) finished in 16 feedlots in southwestern Iowa through the Tri-County Steer Carcass Futurity Cooperative were used for a retrospective analysis. Cattle originated in the Midwest (Iowa, Missouri, Indiana, Illinois, and Minnesota) and were born in February, March, or April of 2002 through 2013. Feedlot performance and carcass composition data were obtained for each animal. Palmer Drought Severity Index (PDSI) values were obtained for each animal's preweaning environment on a monthly basis. Mean PDSI values were used to classify conditions as dry (≤−2.0), normal (>−2.0 and <2.0), or wet (≥2.0) for the cool (April and May), warm (June through August), and combined (April through August) forage growing seasons preweaning. Mixed models were used to evaluate the effects of PDSI class on subsequent performance. Calf sex, date of birth (as day of year), year, and feedlot were also included as fixed effects. When considering PDSI class during the cool season, cattle from normal and wet classes had a greater feedlot delivery BW (P < 0.0001) than dry. Dry and normal classes had greater (P ≤ 0.02) delivery BW than wet during the warm and combined seasons, however. For the cool season, average daily gain was greater (P < 0.0001) for the dry class than normal and wet. Cattle from the normal class for the cool season had greater (P = 0.001) final BW than wet, but the wet class had the greatest (P < 0.04) and dry class had the lowest (P < 0.01) final BW during the warm season. During the cool season, HCW was greater (P < 0.007) for the normal than wet class, although HCW was greater (P ≤ 0.02) for wet compared with dry and normal during the warm season. Calculated yield grade was lower (P ≤ 0.006) for the normal class during the cool season compared with dry and wet. For both the warm and combined seasons, the dry class had lower (P ≤ 0.004) calculated yield grade compared with normal and wet. Carcasses from cattle that experienced normal or wet warm seasons had greater (P ≤ 0.0005) marbling scores than dry, and normal had greater (P = 0.0009) marbling score than dry for the combined seasons. In conclusion, these data indicate that both dry and wet conditions during the preweaning phase may impact ultimate feedlot performance and carcass composition. [ABSTRACT FROM AUTHOR]

Feeding dried distillers grains with solubles (DDGS), a feed high in fat and protein, to lactating beef cows can alter milk production and composition, resulting in improved pre-weaning growth of progeny. This alteration in milk profile may consequently alter the growth and carcass composition of the offspring after weaning. Therefore, Angus×Simmental steers (n=48) whose dams were fed one of two diets supplemented with either DDGS or soybean meal (CON) from calving to mid-lactation were placed in a feedlot to determine the effects of maternal nutrition during lactation on progeny development and carcass composition. Cow–calf pairs were allotted to two treatments at birth based on cow and calf BW, breed and age. Maternal diets were isocaloric (3.97 MJ/kg NEg) and consisted of rye hay supplemented with DDGS at 1% of BW (19.4% CP; 8.76% fat) or rye hay and corn silage supplemented with CON (11.7% CP; 2.06% fat). After conclusion of the treatments at 129 days postpartum, cow–calf pairs were comingled and managed as one group until weaning at 219 days postpartum. Steers were then transitioned to a common diet composed of 60% DDGS, 34% corn silage and 6% vitamin/mineral supplement and were placed indoors in individual pens with slatted floors. An intravenous glucose tolerance test (IVGTT) was performed 134 days after feedlot entry on 16 steers (CON, n=7; DDGS, n=9) to determine the effect of maternal diet on glucose and insulin sensitivity. Steers were slaughtered at a target BW of 645 kg. Categorical and continuous data were analyzed using the GLIMMIX and MIXED procedures of SAS, respectively. Steers from DDGS dams tended to be heavier on day 85 of feedlot finishing (P=0.09) compared with steers from CON dams. However, there were no differences in final weight, average daily gain, dry matter intake or efficiency (gain:feed, P⩾0.18). Maternal treatments did not affect progeny days on feed (P=0.15), despite a mean difference of 9 days in favor of DDGS. Glucose and insulin concentrations and area under the curve of progeny as measured by IVGTT were not affected by maternal diet (P⩾0.16). Maternal DDGS supplementation decreased marbling score (P=0.04), but did not influence carcass grading percentage or any other carcass characteristic (P⩾0.17). [ABSTRACT FROM PUBLISHER]

The objective of this study was to compare pre- and postweaning growth performance, carcass characteristics, and meat quality attributes of calves that did not receive an implant or were implanted early or late in the nursing period. Crossbred steer calves (n = 135) were stratified by birth date and birth weight and randomly assigned to the following implant treatments: control (CON; no preweaning implant), 58 d (EARLY; 36 mg zeranol, administered at an average of 58 ± 13 d of age), and 121 d (LATE; 36 mg zeranol, administered at an average 121 ± 13 d of age). After weaning, steers were blocked by initial feed yard BW to 15 pens (5 pens/treatment and 9 steers/pen). All steers were implanted on d 21 after arrival at the feed yard and again on d 108 of finishing. Steer BW and ultrasound assessment of rib eye area (uREA), rib fat thickness (uRFT), and percent intramuscular fat (uIMF) were collected when implants were administered, at weaning, and on harvest day. Carcass measurements included HCW, rib eye area (REA), 12th-rib fat thickness (FT), and marbling score. Objective color (L*, a*, and b*) was recorded, and a 3.8-cm strip loin section was removed from both sides of each carcass and portioned into 2.54-cm steaks that were aged for 3 or 14 d for analysis of cook loss and Warner-Bratzler shear force (WBSF). The remaining portion of each sample was used for analysis of moisture and crude fat. Steer BW, ADG, and G:F did not differ among treatments (P > 0.05). Steers implanted in the EARLY treatment had a greater (P < 0.05) cumulative DMI than CON but were not different from steers implanted in the LATE treatment. Ultrasound REA and uRFT (averaged across all collection days) did not differ (P > 0.05); however, steers on the CON treatment had a greater (P ≤ 0.05) percent uIMF than EARLY implanted steers, whereas steers receiving the LATE implant were intermediate and not different from the other treatments. Hot carcass weight, REA, FT, USDA yield grade, marbling score, and objective color did not differ (P > 0.05) among treatments. The proportion of steers in each USDA yield and quality grade was similar (P > 0.05) among treatments, and no differences were detected for total carcass value or price per 45.4 kg (hundredweight; P > 0.05). Treatment did not influence (P > 0.05) percent cook loss, crude fat, moisture, or WBSF. In conclusion, administering a nursing implant, regardless of timing, did not influence live performance, carcass characteristics, or meat quality of steers fed in this study. [ABSTRACT FROM AUTHOR]

Three experiments were conducted to determine the effect of increasing concentrations of a smectite clay on toxin binding capacity, ruminal fermentation, diet digestibility, and growth of feedlot cattle. In Exp. 1, 72 Angus × Simmental steers were blocked by BW (395 ± 9.9 kg) and randomly allotted to 3 treatments (4 pens/treatment and 6 steers/pen) to determine the effects of increasing amounts of clay (0, 1, or 2%) on performance. The clay was top-dressed on an 80% concentrate diet at a rate of 0, 113, or 226 g/ steer daily to achieve the 0, 1, and 2% treatments, respectively. Steers were slaughtered at a target BW of 606 kg. In Exp. 2, 6 steers (596 ± 22.2 kg initial BW) were randomly allotted to the same 3 treatments in a replicated 3 × 3 Latin square design (21-d periods) to determine the effects of increasing amounts of clay on ruminal pH, VFA, and nutrient digestibility. In Exp. 3, 150 mg of clay was incubated in 10 mL of rumen fluid with 3 incremental concentrations (6 replicates per concentration) of aflatoxin B1 (AFB1) or ergotamine tartate (ET) to determine binding capacity. During the first 33-d period, there was a quadratic effect of clay on ADG (P < 0.01) and G:F (P < 0.01), increasing from 0 to 1% clay and then decreasing from 1 to 2% clay. However, during the second 30-d period, clay linearly decreased ADG and G:F (P ≤ 0.03) and overall ADG, DMI, and G:F were not impacted (P ≥ 0.46). Clay linearly decreased marbling score (P = 0.05). Hepatic enzyme activity did not differ among treatments on d 0 or at slaughter (P ≥ 0.15). Clay linearly decreased ruminal lactate and propionate, linearly increased formate and the acetate:propionate ratio (P ≤ 0.04), and tended (P = 0.07) to linearly increase butyrate. Clay tended to linearly increase (P = 0.06) OM and CP apparent digestibility. Ruminal pH, urine pH, and other digestibility measures did not differ among treatments (P ≥ 0.15). Clay was able to effectively bind AFB1 and ET at concentrations above the normal physiological range (52 and 520 μg/mL), but proportional adsorption was decreased to 35.5 and 91.1% at 5,200 μg/mL (P < 0.01) for AFB1 and ET, respectively. In conclusion, clay effectively binds ruminal toxins, decreases ruminal lactate, and improves performance only during adaptation to a high-concentrate feedlot diet. [ABSTRACT FROM AUTHOR]

Bovine viral diarrhea virus (BVDV) has major impacts on beef cattle production worldwide, but the understanding of host animal genetic influence on illness is limited. This study evaluated rectal temperature, weight change and feed intake in Bos indicus crossbred steers (n = 366) that were challenged with BVDV Type 1b, and where family lines were stratified across three vaccine treatments of modified live (MLV), killed, (KV) or no vaccine (NON). Pyrexia classification based on 40.0 °C threshold following challenge and vaccine treatment were investigated for potential interactions with sire for weight change and feed intake following challenge. Pyrexia classification affected daily feed intake (ADFI, p = 0.05), and interacted with day (p < 0.001) for ADFI. Although low incidence of clinical signs was observed, there were marked reductions in average daily gain (ADG) and cumulative feed intake during the first 14 day post-challenge; ADG (CV of 104%) and feed efficiency were highly variable in the 14-day period immediately post-challenge as compared to the subsequent 14-day periods. A sire × vaccine strategy interaction affected ADFI (p < 0.001), and a sire by time period interaction affected ADG (p = 0.03) and total feed intake (p = 0.03). This study demonstrates that different coping responses may exist across genetic lines to the same pathogen, and that subclinical BVDV infection has a measurable impact on cattle production measures. [ABSTRACT FROM AUTHOR]

Nelore is the most economically important cattle breed in Brazil, and the use of genetically improved animals has contributed to increased beef production efficiency. The Brazilian beef feedlot industry has grown considerably in the last decade, so the selection of animals with higher growth rates on feedlot has become quite important. Genomic selection (GS) could be used to reduce generation intervals and improve the rate of genetic gains. The aim of this study was to evaluate the prediction of genomic-estimated breeding values (GEBV) for average daily weight gain (ADG) in 718 feedlot-finished Nelore steers. Analyses of three Bayesian model specifications [Bayesian GBLUP (BGBLUP), BayesA, and BayesCπ] were performed with four genotype panels [Illumina BovineHD BeadChip, TagSNPs, and GeneSeek High- and Low-density indicus (HDi and LDi, respectively)]. Estimates of Pearson correlations, regression coefficients, and mean squared errors were used to assess accuracy and bias of predictions. Overall, the BayesCp model resulted in less biased predictions. Accuracies ranged from 0.18 to 0.27, which are reasonable values given the heritability estimates (from 0.40 to 0.44) and sample size (568 animals in the training population). Furthermore, results from Bos taurus indicus panels were as informative as those from Illumina BovineHD, indicating that they could be used to implement GS at lower costs. [ABSTRACT FROM AUTHOR]

Objetivou-se avaliar o efeito do nível de concentrado e dos sais de cálcio de ácidos graxos (SCAG) sobre o desempenho e qualidade da carne de novilhos terminados em confinamento. Sessenta novilhos Nelore e cruza Nelore foram divididos em quatro grupos e confinados por um período de 85 dias com as seguintes dietas: (BC) 46,7% de concentrado; (BC-SCAG) dieta BC acrescida de 3% de SCAG; (AC) dieta contendo 76,6% de concentrado e (AC-SCAG) dieta AC com 3% de SCAG. O nível de concentrado não influenciou o ganho médio diário, a espessura de gordura subcutânea e a área de olho de lombo, mas as dietas AC aumentaram o peso (P=0,0011) e o rendimento (PThe objective of this research was to evaluate the effects of concentrate level and calcium salts of fatty acids (SCAG) on performance and meat quality of feedlot finished steers. Sixty Nellore and Nellore crossbred steers were distributed in four groups and fed for 85 days with one of the following diets: BC) diet containing 46.7% of concentrate; (BC-SCAG) LC diet plus 3% of SCAG; (AC) diet containing 76.6% of concentrate and (AC- SCAG) HC diet plus 3% of SCAG. Concentrate level did not affected average daily gain, subcutaneous fat thickness and ribeye area, but AC diets increased carcass weight (P=0.0011), dressing percentage (P

Bovine viral diarrhea virus (BVDV) has major impacts on beef cattle production worldwide, but the understanding of host animal genetic influence on illness is limited. This study evaluated rectal temperature, weight change and feed intake in Bos indicus crossbred steers (n = 366) that were challenged with BVDV Type 1b, and where family lines were stratified across three vaccine treatments of modified live (MLV), killed, (KV) or no vaccine (NON). Pyrexia classification based on 40.0 °C threshold following challenge and vaccine treatment were investigated for potential interactions with sire for weight change and feed intake following challenge. Pyrexia classification affected daily feed intake (ADFI, p = 0.05), and interacted with day (p < 0.001) for ADFI. Although low incidence of clinical signs was observed, there were marked reductions in average daily gain (ADG) and cumulative feed intake during the first 14 day post-challenge; ADG (CV of 104%) and feed efficiency were highly variable in the 14-day period immediately post-challenge as compared to the subsequent 14-day periods. A sire × vaccine strategy interaction affected ADFI (p < 0.001), and a sire by time period interaction affected ADG (p = 0.03) and total feed intake (p = 0.03). This study demonstrates that different coping responses may exist across genetic lines to the same pathogen, and that subclinical BVDV infection has a measurable impact on cattle production measures.

Objetivou-se com este trabalho avaliar os efeitos do milho grão seco ou úmido e dos sais de cálcio de ácidos graxos no desempenho e nas características de carcaça de novilhos Nelore confinados na fase de terminação. Quarenta e oito animais com peso inicial de 431 ± 29,8 kg foram alimentados durante 70 dias com uma das seguintes dietas: MGS - dieta basal composta de silagem de milho (40%), milho grão seco (48,4%), farelo de soja (7,6%), uréia, sufato de amônia, cloreto de potássio, sal mineral, rúmen tamponante e rumensina (4%); MGU - dieta basal, com substituição do MGS por milho grão úmido; MGS-SCAG - dieta basal contendo 45% de MGS e 4% de sais de cálcio de ácidos graxos; MGU-SCAG - dieta basal com 45% de milho grão úmido e 4% de sais de cálcio de ácidos graxos. O ganho médio diário não foi influenciado pelo tipo de grão de milho, no entanto, a ingestão de MS pelos animais da dieta MGU foi menor que naqueles alimentados com a dieta MGS e resultou em maior eficiência alimentar para a dieta MGU. O maior número de protozoários ciliados ruminais foi observado nos animais alimentados com a dieta MGU. O rendimento de carcaça, a gordura renal pélvica e inguinal e a espessura de gordura subcutânea foram maiores nos animais alimentados com a dieta MGS. O ganho de peso médio diário também não diferiu entre os animais tratados ou não com SCAG, no entanto, a ingestão de MS foi maior nos animais alimentados com a dieta SCAG. Não houve influência sobre a eficiência alimentar. O número de protozoários ruminais foi menor nos animais alimentados com as dietas contendo SCAG, no entanto, as características de carcaça não foram influenciadas por essa dieta.The aim of this work was to evaluate the effects of dry corn grain or high moisture corn and calcium salts of fat acids on the performance and carcass traits of feedlot fed Nellore steers on finishing phase. Forty eight animals with 431 ± 29.8kg of initial mean body weight were fed during 70 days, with one of the four diets: MGS - basal diet containing corn silage (40%), dry corn grain (48.4%), soybean meal (7.6%), urea, amonium sulphate, mineral salt, limestone and monensin (4%); MGU - basal diet with high moisture corn replacing MGS; MGS-SCAG basal diet with 45% of MGU and 4% of calcium salts of fatty acids; MGU-SCAG - basal diet with 45% of MGS and 4% of calcium salts of fatty acids. The average daily gain was not affected by grain type. However, dry matter intake of animals of MGU treatment was smaller than MGS treatment, with a greater feed efficiency for MGU treatment. A greater number of ruminal ciliate protozoa was found in MGU treatments. Dressing percentage, renal, pelvic and inguinal fat and backfat thickness were greater in animals fed MGS diet. Average daily gain was not different between animals fed with or without SCAG, although, dry matter intake was greater in diets with SCAG, with no effect on feed efficiency. Protozoa number was smaller in diets containing SCAG and carcass traits were not affected by SCAG.

The objective of the present study to assess the effects of mesquite pod addition replacing corn (0, 250, 500, 750, and 1000 g/kg in the dry matter basis) on nutrient intake, animal performance, feeding behavior, nutrient digestibility, nitrogen balance, and microbial protein synthesis. Twenty-five Holstein-Zebu crossbred dairy steers at 219 ± 22 kg initial body weight and 18 months of age were used. The experiment lasted 84 days, divided into three periods of 28 days. A completely randomized design was used, and data were submitted to analysis using PROC GLM for analysis of variance and PROC REG for regression analysis using the software Statistical Analysis Systems version 9.1. Experimental diets were composed of Tifton 85 hay, soybean meal, ground corn, mesquite pod meal, and mineral salt. Samples of food offered were collected during the last 3 days of each period, and the leftovers were collected daily, with samples bulked per week. At the end of each 28-day period, the remaining animals were weighed to determine total weight gain and average daily gain. The assessment of behavioral patterns was performed through instantaneous scans in 5-min intervals for three consecutive 12-h days. A single urine sample from each animal was collected on the last day of each collection period at about 4 h after the first feeding. The replacement of corn by mesquite pod meal did not significantly influence treatments regarding nutrients intake, animal performance, and feeding behavior. Retained and consumed nitrogen ratio did not statistically differ between replacement levels. Likewise, there were no statistical differences regarding microbial protein synthesis and efficiency between replacement levels. Mesquite pod meal can be used in Holstein-Zebu crossbred dairy steers' diet with total corn replacement. [ABSTRACT FROM AUTHOR]

The objective of this research was to use data from multiple studies to comprehensively quantify the effects of feeding 1) laidlomycin propionate (LP), alone and/or in combination with chlortetracycline, compared with 2) monensin sodium (MS), alone and/or in combination with tylosin, at commercially approved dosages, on ADG, DMI, feed efficiency (FE), mortality, and carcass characteristics (HCW and liver abscesses). A secondary objective was to explore potential sources of heterogeneity among the comparative effectiveness studies. A systematic review of peer-reviewed literature and industry reports was used to identify studies that included direct comparisons of these treatments in finishing steers in North America. Random-effects meta-analysis models of performance, carcass, and health-related outcomes were fitted with extracted data, consisting of a total of 17 data sets comprising a total of 135 pens and 13,603 steers. Results showed that pens of steers fed LP had increased ADG (live and carcass adjusted), DMI, and HCW compared with those fed monensin (P < 0.05). However, liver abscesses were more common in LP-fed cattle than in MS-fed cattle (P < 0.05), presumably because of differences in the concurrently fed antimicrobials. No significant effects (P > 0.05) were identified for FE or for health-related outcomes (overall and cause-specific mortality). There was a substantial amount of heterogeneity in outcomes among studies, and when pen size and type of production setting were included in mixed-effects metaregression models, they accounted for only a small proportion of the between-study heterogeneity found in the meta-analysis models. Therefore, caution should be exercised when interpreting summary estimates in the presence of substantial heterogeneity. However, these results provide comprehensive information on the comparative effects of different ionophores across multiple studies and multiple years, states, and production settings. These unique results can enable quantitative and informed decisions by potential end users of these feed additives that are widely used in the U.S. beef industry for reducing the costs of beef production through enhanced cattle performance. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate nutrient intake, diet digestibility, performance and carcass characteristics of Santa Inês crossbred lambs fed diets cottonseed cake in substitution of soybean meal. Forty Santa Inês × Dorper crossbred noncastrated rams with average initial weight of 20.9 ± 2.5 kg were distributed in a completely randomized design with four treatments and ten replicates. The diets were composed of Tifton 85 ( Cyndon dactylon cv. Tifton-85) hay as roughage and cottonseed cake replacing 0, 33, 66 and 100% of soybean meal, in a roughage-to-concentrate ratio of 50:50. At the end of the experiment, the lambs were slaughtered and their carcasses were evaluated. Except for crude protein and ether extract, overall, the digestibility coefficients of the nutrients decreased linearly (P < 0.05) as the levels of cottonseed cake in the diets were elevated. The cottonseed cake levels in substitution of soybean meal also did not affect final body weight, daily weight gain and total weight gain of the lambs (P > 0.05). The qualitative and quantitative carcass characteristics did not differ (P > 0.05) among the levels of cottonseed cake in substitution of soybean meal. Although the hot and cold carcass yields decreased (P < 0.05) as the cottonseed cake increased its participation in the diet, these variables remained within the levels considered satisfactory. Cottonseed cake can replace up to 100% of soybean meal in the concentrate, which corresponds to 12% of the total diet for lambs, representing an important food alternative to substitute soybean meal. [ABSTRACT FROM AUTHOR]

Sixteen Holstein beef cattles, weighing 270 kg and 5-6 months age, were assigned to one of two treatments (8 animal per treatment) in a completely randomized design. All animals in both groups fed with basal diet containig; concentrated feed, barley, cottonseed meal and straw. Live yeast culture (Saccharomyces cerevisiae, 1,4 X 108 cfu/g) incorporated into yeast group rations 50 g/d. The study lasted 135 days. At the beginning of the trial, animals were adapted to the basal diet over a 15- day period. Feed consumption was measured daily, while body weight and body weight gain was measured monthly. At the end of the study, four animals from each groups were slaughtered and the hot carcass yield was determined. Rumen contents were collected on days 45th and 90th analyzed for pH, volatile fatty acids and ammonia-N (NH3-N). Dietary treatment had no effect (p>0,05) on DMI (Dry matter intake), FCR (Feed conversion ratio), final live body weight, and ADG (Avarage daily gain) (p>0,05). Carcass yield was significantly (p 0,05) increased by dietary inclusion of yeast so that carcasss yield was 50,65% and 52,75% in control and yeast group respectively, in the yeast group. There was also no significant (p>0,05) differences for rumen volatile fatty acids (VFA) and ammonia-N between each groups. However, rumen pH was lower (p<0,05) for the yeast group. No differences (p>0,05) between groups were observed regarding blood parameters. [ABSTRACT FROM AUTHOR]

Virginiamycin (VIR) and monensin (MON) are included in high concentrate diets to mitigate digestive disturbances and to increase performance of ruminants in intensive systems. Megasphaera elsdenii strain NCIMB 41125 (Me) rapidly utilises lactate in the rumen, thereby controlling ruminal pH and digestive disturbances. Me promotes butyrate and valerate production whereas VIR and MON promote propionate that is gluconeogenic and perceived to be more favourable to performance. The objective of the present study was to determine whether the ratio between VFA proportions is more favourable when VIR or MON is administered together with Me and whether their respective effects on health and performance are additive. Two studies of factorial design were conducted, one in vitro fermentation trial where VIR or MON was incubated in the absence of Me (Me-) or in the presence of Me (Me+), and one in vivo trial with steers where MON or Me was administered alone or together. In the in vitro trial VIR and MON were administered to the fermentation vessels in two concentrations, a low dose (0.125 µg/mL) and a high dose (0.375 mg/mL). Me was administered at 100 µL/40 mL, supplying 2.5×10 5 cfu/mL. In the in vivo trial 224 Bonsmara steers were allocated to a finishing diet with 80 kg/ton roughage and 224 were allocated to a finishing diet with 20 kg/ton roughage. Within each diet 112 steers received MON (MONY) and 112 not (MONN) and 112 steers within each diet were dosed with Me (MeY) and 112 not (MeN). In the in vitro trial VIRMe- and MONMe- decreased gas production, whereas VIRMe+ and MONMe+ increased fermentation. VIRMe- and to a lesser extent MONMe- increased total bacterial counts, a result which was apparently due to stimulation of M. elsdenii numbers as determined by 16R DNA sequencing, although other lactate utilising bacteria could have contributed. Me+ reduced lactate and the reduction was more in VIRMe+ and MONMe+. Fermentation end products in Me+ favoured butyrate and valerate and VIRMe- and especially MONMe-, propionate. VIRMe+ and MONMe+ displayed the median. In the steer trial MONY decreased intake and improved feed conversion efficiency. MONY increased carcass gain and dressing percentage on the 80 kg/ton roughage diet but not the 20 kg/ton roughage diet. Rumen score on both diets was improved by MONY and liver score by MONYMeY on the 20 kg/ton roughage diet. Carcass weight was improved by MONNMeY on the 20 kg/ton roughage diet. Morbidity and mortality were not affected by MONY but were improved in the presence of Me (MeY). In general, the results suggest synergy between MON and Me. [ABSTRACT FROM AUTHOR]

This research evaluated the effects of supplementing extruded dried distillers' grains (DDG) cubes to grazing steers on subsequent finishing performance and carcass characteristics. Steers (n = 140) grazed tall fescue (Festuca arundinacea)/bermudagrass (Cynodon dactylon) pastures from 14 April to 17 September 2020 with supplementation treatments (n = 3 pastures/treatment) that included: 1) Fertilized Control (FC), no supplementation on N fertilized pastures (112 kg N/ha); 2) Fertilized Supplement (FS), supplemented DDG cubes at 2.9 kg/d prorated for 3-d/wk feeding on N fertilized pastures; and 3) Supplement (S), supplemented DDG cubes at 0.75% of BW/d prorated for 5-d/wk feeding on unfertilized pastures. All animals were followed through the finishing phase in a commercial feedyard to investigate carryover effects on feedlot performance in 2 pens comingled across supplemental treatment. Carcass characteristics were evaluated via ultrasonography on d0 and d84 of finishing, and measurements were obtained at harvest. Feed DMI were segregated to individual animals according to Guiroy et al. (2001) and Tedeschi and Fox (2020b). Supplemented animals were heavier (P < 0.01) at feedlot entry than FC, but harvest BW did not differ (P = 0.23). However, S and FS required 37 fewer days on feed (P = 0.01) than FC. Supplementation on pasture reduced total feed required (P = 0.02) and feed costs (P = 0.01) relative to FC. Gains were greater (P = 0.02) for FC and FS than S from d0 to d84, but did not differ thereafter (P = 0.15). At harvest, FC had the greatest dressing percent (P < 0.01) and lower yielding carcasses than FS (P = 0.01), but did not differ (P = 0.11) from S. Overall, extruded DDG cube supplementation during grazing did not negatively affect subsequent feedlot performance or carcass characteristics, but reduced the total feed required for finishing. [ABSTRACT FROM AUTHOR]

Sixty-nine Angus-sired steer calves (332.3 kg initial BW) were used to determine the effects of single or double implant strategies on steers of high or low genetic potential (GP) determined by the GeneMax (Zoetis, Florham Park, NJ) genetic profiling test. Steers were assigned to treatments in a 2 2 factorial design with factors of 1) composite GP score (high, mean GP score of 86.5 [HI]; low, mean GP score of 25.3[LO]) and 2) implant strategy (single, steers implanted on d 70 [1X], or double, steers implanted d 0 and 70 [2X]). All steers were given the same implant (Revalor-S; Merck Animal Health, Summit, NJ), with the 2X group implanted on d 0 and 70 and the 1X group implanted only on d 70. A diet containing 1.38 Mcal NEg/kg DM was fed ad libitum, once daily. Ultrasound was used to measure body composition characteristics on d 0 and 70. Steers were harvested after 140 d on feed. At both the d-0 and d-70 ultrasound, HI steers had greater (P < 0.001) percent intramuscular fat (IMF) than LO steers, but no differences (P = 0.24) were observed in LM area (LMA), rib fat thickness (RF), or rump fat thickness (RMFT). Steers in the 2X group had larger (P = 0.02) LMA and less (P = 0.03) IMF on d 70 than 1X steers and no differences (P = 0.50) in RF or RMFT were observed. From d 0 to 70, HI steers had ADG, DMI, and G:F (P = 0.60) similar to LO steers; however, 2X steers had greater (P < 0.001) ADG and were more (P < 0.001) feed efficient compared with 1X steers during the same interval. Over the entire 140-d feeding period, there were no differences (P = 0.6) in BW, ADG, DMI, or G:F between GP groups; however, 2X steers had greater (P = 0.03) ADG compared with 1X steers and still had similar (P = 0.12) DMI and G:F. Upon slaughter, marbling score tended to be impacted by a GP implant interaction (499.9 ± 18.5, 545.6 ± 18.5, 487.1 ± 18.5, and 469.8 ± 18.5 for HI and 2X, HI and 1X, LO and 2X, and LO and 1X, respectively; P = 0.06). No differences (P = 0.7) were observed between GP groups for HCW, LMA, RF, KPH, or yield grade (YG). Steers in the 1X group had less (P = 0.003) RF than 2X steers but similar (P = 0.14) HCW, marbling, LMA, KPH, and YG. A greater proportion (P = 0.03) of HI steers had choice carcasses (100 ± 0.0%) compared with LO steers (87.8 ± 3.9%). Results of this study indicate that the GP test used in the current study predicted differences in IMF, carcass marbling, and percent carcasses graded as choice. [ABSTRACT FROM AUTHOR]

The research objective, during a 3-yr study, was to compare starch- and fiber-based 38 d weaning transition diets (WTD) to identify the effect on calf performance, feed intake and feed efficiency (FE). Subsequently, the effect of WTD on feedlot finishing performance and cow and calf net return was determined. Crossbred steer and female calves (Angus x Hereford x Gelbvieh; n=405; Age=7.5 month; BW=278±4.3 kg) were randomly assigned to six treatments (4 pen replicates/treatment) based on age and weaning weight. Starch-based WTD were formulated with soybean meal (SBM) and field pea (FP), and fiber-based diets were formulated with increasing levels of FP (0-30%). Pelleted WTD treatments were: 1-(CSBM) starch-base+SBM, 2-(CPEA) starch-base+FP, 3-(0PEA) fiber-base+0% FP, 4-(10PEA) fiber-base+10% FP, 5-(20PEA) fiber-base+20% FP, and 6-(30PEA) fiber-base+30% FP. The CSBM, 0PEA, 10PEA, and 20PEA treatments had greater gain and average daily gain (ADG) compared to the CPEA and 30PEA (P<0.01), and the CPEA treatment had the lowest gain and ADG (P<0.001). Dry matter intake (DMI) was greatest for the fiber-based 0PEA and 20PEA WTD treatments and lowest for the starch-based CSBM and CPEA (P<0.001), and WTD did not affect FE (P=0.39). In addition, feedlot finishing performance and carcass measurements were not affected by WTD (P>0.10). Therefore, we conclude that FP can replace up to 20% of fiber-based ingredients in WTD without affecting DMI and ADG. However, the highest cow-calf net return was from the CSBM, 20PEA and 30PEA WTD treatments (P<0.001). [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the effects of alternative finishing strategies on feedlot performance and carcass characteristics. Beef steers (64 pens; 8 steers/pen) were allocated to a randomized complete block design with a 2 × 2 factorial treatment arrangement. Factor 1 consisted of diet, with cattle fed a conventional (CON) diet or a diet consisting of Programmed Nutrition Beef Program (PN) supplements. The PN treatment included Programmed Nutrition Beef Receiver fed from d 1 through 20 of feeding and Programmed Nutrition Beef Finisher fed from d 21 to harvest. Factor 2 evaluated the presence (EGP+) or absence (EGP-) of exogenous growth promotants (ExGP) in the production system. Steers in the EGP+ treatments were initially implanted with Component E-S, reimplanted with Component TE-IS, and fed 400 mg.animal-1.d-1of ractopamine hydrochloride for the final 28 d before harvest. Steers were harvested on d 175, and strip loins were removed from 2 carcasses selected at random from each pen for transport to Kansas State University. One 1.27-cm-thick steak was removed from the anterior face for proximate and long-chain fatty acid analysis. There were no diet × ExGP interactions (P > 0.10) for feedlot performance except for DMI (P = 0.02). Steers in the PN/ EGP+ treatment consumed more feed than all other treatments (P < 0.05). Both diet and ExGP affected DMI (P < 0.05), with PN and EGP+ steers consuming more feed than their contemporaries. Gain:feed and ADG were unaffected (P > 0.10) by diet, but ExGP improved these measures (P < 0.01). There were no diet × ExGP interactions for carcass characteristics except KPH fat and percentages of yield grade 3 and 4 carcasses (P < 0.05). Diet affected total incidence of liver abscesses because PN steers had a greater (P = 0.05) incidence of liver abscesses than steers in the CON treatment. Diet did not affect the other carcass characteristics (P > 0.10). Use of ExGP increased (P < 0.05) HCW, LM area, and 12th-rib fat but did not affect (P > 0.10) marbling score. Using ExGP reduced the percentage carcasses grading Premium Choice (P < 0.05). No diet × ExGP interactions or diet effects were detected for long-chain fatty acid profiles (P > 0.10). Use of ExGP increased (P < 0.05) the ratio of saturated:unsaturated fatty acids. In summary, the alternative feeding strategy presented in this study produced similar feedlot performance and carcass characteristics compared with a conventional feedlot system. [ABSTRACT FROM AUTHOR]

The protein-sparing effect of condensed tannins (CT) was investigated in growing lambs fed a low- or high-protein diet during a 50-day period. Isocaloric diets containing 106 g crude protein/kg dry matter (DM) (low protein; LP) or 138 g crude protein/kg DM (high protein; HP) were formulated using 70 % concentrate, 15 % corn silage, and 15 % dried licorice leaves, providing CT (4.1 g/kg DM). Twenty-four crossbred male lambs (3-4 months old, 23.9 ± 5.2 kg body weight) were assigned to one of four diets: LP with polyethylene glycol (PEG; 40 g/kg DM) supplementation (LP + PEG), LP without PEG supplementation (LP − PEG), HP with PEG supplementation (HP + PEG), and HP without PEG supplementation (HP − PEG). The effect of dietary crude protein level and CT on feed intake was not significant ( P > 0.05). However, a positive effect on daily gain ( P < 0.001) and feed conversion ratio (FCR; P < 0.01) was observed in lambs fed with HP diets. An interaction effect between crude protein level and PEG was observed, and consequently, FCR was higher in group LP + PEG (10.1; P < 0.05) than in groups LP − PEG (7.3), HP + PEG (5.3), or HP − PEG (5.4). There was also an interaction effect between crude protein level and PEG on kidney, pelvic, and heart fat, presenting a higher relative weight in group LP + PEG (12.6 g/kg) than in group HP + PEG (9.2 g/kg; P < 0.05), but no ( P > 0.05) in groups without PEG supplementation. These preliminary results suggest that the use of CT can minimize the negative effect of low-protein diets on FCR in lambs. [ABSTRACT FROM AUTHOR]

Liver abscess has been identified in multiple classes of cattle, but cattle consuming higher energy diets may have greater prevalence of abscessation. The presence and severity of liver abscess has been associated with reduced dry matter intake, daily gain, and gain efficiency of individually fed animals, and as the prevalence of abscesses within pens of animals increases, growth performance worsens. Because of the importance of the liver to metabolism, damage due to abscess could negatively affect energy utilization. A preliminary analysis indicates severe liver abscess incidence increases the requirement of metabolizable energy for maintenance., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Simple Summary: Maternal nutrient restriction in beef cows can impact developmental processes in the fetus, which may influence lifetime performance. If feed is limited, a maternal deficiency in protein and/or energy can occur. As a result, the fetus may receive inadequate levels of nutrients, potentially altering fetal development. In the present study, we evaluated the impact of a metabolizable protein restriction during mid- and/or late-gestation on progeny carcass characteristics. First-calf heifers were provided with a diet that either met their metabolizable protein requirements or caused an 80% restriction in metabolizable protein during mid- and/or late-gestation in a crossover design. Our results suggest that heifers catabolized lean body tissue, but not body fat stores, to overcome the metabolizable protein deficiency. However, restricting metabolizable protein in gestating heifers did not substantially influence the feedlot performance or carcass characteristics of their offspring. The restricted dams may have buffered their offspring from the metabolizable protein limitation during gestation. This study investigated the impacts of metabolizable protein (MP) restriction in primiparous heifers during mid- and/or late-gestation on progeny performance and carcass characteristics. Heifers were allocated to 12 pens in a randomized complete block design. The factorial treatment structure included two stages of gestation (mid- and late-) and two levels of dietary protein (control (CON); ~101% of MP requirements and restricted (RES); ~80% of MP requirements). Half of the pens on each treatment were randomly reassigned to the other treatment at the end of mid-gestation. Progeny were finished in a GrowSafe feeding system and carcass measurements were collected. Gestation treatment x time interactions indicated that MP restriction negatively influenced heifer body weight (BW), body condition score, and longissimus muscle (LM) area (p < 0.05), but not fat thickness (p > 0.05). Treatment did not affect the feeding period, initial or final BW, dry matter intake, or average daily gain of progeny (p > 0.05). The progeny of dams on the RES treatment in late gestation had a greater LM area (p = 0.04), but not when adjusted on a hot carcass weight basis (p > 0.10). Minimal differences in the animal performance and carcass characteristics suggest that the level of MP restriction imposed during mid- and late-gestation in this study did not have a significant developmental programming effect. [ABSTRACT FROM AUTHOR]

There are concerns about antagonisms between immunity and animal productivity in livestock production. The objective of this study was to evalu-ate the effect of antibody levels through a response to vaccination protocol, weaning timing, and their interac-tion on performance and carcass quality traits in Angus beef cattle. Final antibody level and response to vac-cination were based on neutralizing serum antibodies against bovine viral diarrhea virus type 2 (BVDV2). Calves were followed through development and the feedlot phase, with collection of yearling ultrasound (,n = 957), preharvest (n = 762), and carcass (n = 673) data. In this study, 48% of the animals were observed to have positively responded to the vaccine, as evidenced by higher final antibody levels compared to prevacci-nation antibody levels. Increased final antibody levels were significantly (P < 0.05) associated with increased yearling weight and increased subcutaneous fat over the rump. An interaction between final antibody level and weaning time also was associated (P < 0.05) with Warner-Bratzler shear force (WBSF) and meat pH, with a favorable, negative relationship between final anti-body and WBSF in calves weaned at initial vaccination. Overall antibody response by wean time interaction had a significant (P < 0.05) association with ADG and meat pH, with calves weaned at initial vaccination having a favorable, positive relationship between overall anti-body response and ADG. Under both the final antibody and overall antibody response models, animals weaned at initial vaccination had significantly (P < 0.05) lower intramuscular fat at yearling time and conversely higher harvest weight than animals weaned at the booster vac-cination. When antibody response was grouped (none, low, high), a significant interaction (P < 0.05) between antibody response group and weaning time was iden-tified for ADG, harvest weight, and HCW. Animals weaned at the initial vaccination in the high antibody response group had the advantage for ADG, harvest weight, and HCW compared to animals in the high-response group that were weaned at booster vaccination. Linear increases in antibody response generally did not have negative effects on performance or carcass quality traits in finished cattle (P > 0.05). Therefore, producers should not be concerned about decreased production or quality attributes as a result of developing a robust anti-body response to vaccination for BVDV2 in beef cattle. [ABSTRACT FROM AUTHOR]

Abstract: Twenty-four entire male Kacang kid goats were fed diets containing 3% canola (n=12) or palm oil (n=12) supplements for 16weeks. The goats had an initial live weight of 14.2±1.46kg and were fed a mixed ration ad libitum (10.4MJ/ME and 14% crude protein). There was no difference in feedlot performance due to diet. Inclusion of canola oil reduced (P <0.05) kidney fat weight and increased (P <0.05) linolenic acid (18:3n−3) concentration in the blood plasma, m. longissimus lumborum (LL), liver, and kidney. The palm oil diet increased (P <0.05) myristic (14:0) and palmitic (16:0) acid content in the blood, but this did not alter these fatty acids in the LL muscle. Lipid oxidative substances in the liver and LL from palm oil fed kids were higher (P <0.05) than those from canola supplemented kids. The incorporation of canola oil into the goats'' diet increased muscle omega-3 fatty acid content, but lipid oxidation was lowered in the blood and muscle LL. [Copyright &y& Elsevier]

Feed cost has a significant effect on the economic efficiency of feedlot lambs; therefore, the use of low-cost non-conventional feedstuffs, such as olive pulp (OP), has the potential to decrease the production costs. Because optimum inclusion of OP-treated silages has not been determined in feedlot lambs, an experiment was conducted to determine the effect of inclusion of OP ensiled with additives in the diet on the feedlot performance and carcass attributes of feedlot lambs. Ram lambs of Mehraban and Ghezel breeds ( n = 50 lambs per breed) were randomly allotted to 10 groups and fed with one of the nine diets containing OP silage or a control diet. Silage treatments were: (1) OP silage without additives (OPS), (2) OP ensiled with 8 % beet molasses and 0.4 % formic acid (OP-MF), and (3) OP ensiled with 8 % beet molasses, 0.4 % formic acid and 0.5 % urea (OP-MFU). The control diet contained 50 % alfalfa hay and 50 % barley grain. Three levels from each silage were chosen to replace the barley grain (10, 20, or 30 % dry matter basis). The lambs were slaughtered after 92 days, and the average daily gain (ADG), feed conversion ratio (FCR), and carcass characteristics were determined. Feeding OPS to fat-tailed lambs, at an inclusion level of 30 %, decreased the carcass dressing percentage, mainly as a result of decreased brisket percentage, but the ADG and FCR values were not adversely affected. Ghezel lambs had higher ADG than Mehraban lambs, but the visceral fat weight percentage, flap weight percentage, and back fat depth were higher in Mehraban. The crude protein content in the longissimus dorsi (LD) muscle was higher in Ghezel, but the dry matter percentage was higher in Mehraban ( P < 0.05). Other attributes were not significantly affected by breed ( P > 0.05). Most carcass characteristics, including major cuts, were not affected by OPS feeding; therefore, feeding OPS (up to 30 %) can be economical for feedlot lambs. Most carcass characteristics, including major cuts, were not affected by OPS levels used in this experiment; therefore, inclusion of OPS (up to 30 %) in the diet may reduce the cost of raising feedlot lambs. This also could help alleviate the problem of storage of OP in oil factories. [ABSTRACT FROM AUTHOR]

Crossbred steers (n = 180; 230 ± 6 kg) were fed during a 56-d receiving period to determine if supplementing chromium (Cr; KemTRACE Chromium Propionate 0.04%, Kemin Industries) would improve feedlot performance and health of newly-received cat-tle. A completely randomized block design (36 pens; 9 pens/treatment; 5 steers/pen) was used. Chromium pre-mixes were supplemented to add 0 (Con), 0.1, 0.2, or 0.3 mg/kg of Cr to the total diet on a DM basis. No differences were detected on d 0 or after the first 14 d on feed. From d 0 to d 28, DMI (P = 0.07) and ADG increased linearly (P = 0.04) as Cr concentrations increased. From d 0 to d 56, BW (P = 0.08) displayed a tendency to increase linearly, and consequently ADG and G:F increased linearly (P < 0.05) as Cr concentra-tions increased. The number of steers treated at least once for respiratory symptoms tended (P = 0.07) to lin-early decrease as Cr concentrations increased. Twenty additional steers (235 ± 4 kg) were fed 56 d to deter-mine if supplementing Cr (Con or 0.2 mg/kg Cr) would alter the metabolic response of newly-received cattle to a lipopolysaccharide (LPS) challenge. Cattle were samples were collected at 0.5-h intervals from -2 to 8 h, and again at 24 h relative to a LPS challenge (0.5 pg/ kg BW) at 0 h. Serum glucose, insulin, and NEFA con-centrations were determined from blood samples. Steer BW was also measured at cannulation, and 24 h and 8 d post-LPS. Steer BW did not differ at cannulation (P = 0.37), but 24 h post-LPS, Cr-supplemented steers had lost less BW (P = 0.03). Pre-LPS glucose concentra-tion did not differ (P = 0.97). Post-LPS, there was a time x treatment interaction (P <0.01) such that glucose concentration peaked earlier (0.5 h) and at a greater con-centrations in Cr-supplemented steers (P < 0.01). Insulin concentration did not differ between treatments pre- or post-LPS (P > 0.13). Concentration of NEFA did not dif-fer pre-LPS (P = 0.54); but 0.5 h post-LPS Cr-treated steers produced a greater peak NEFA concentration (P < 0.04). Results of this study indicate that supplementation of Cr to the basal diet can have beneficial effects on the performance and health of newly-received steers. These data also suggest that supplementation of Cr attenuated BW loss and allowed for a quicker recovery after a LPS challenge fitted with jugular catheters on d 52. On d 55, blood [ABSTRACT FROM AUTHOR]

Feedlot producers often exceed NRC recommendations for vitamin A and D supplementation; however, increased concentrations of these vitamins have been shown to limit adipocyte differentiation in vitro. A feedlot trial was conducted using 168 Angus crossbred steers (BW = 284 ± 0.4 kg) allotted to 24 pens. The experiment had a 2 × 2 factorial arrangement of treatments: no supplemental vitamin A or D (NAND), 3,750 IU vitamin A/kg dietary DM with no supplemental vitamin D (SAND), no supplemental vitamin A and 1,860 IU vitamin D/kg dietary DM (NASD), and 3,750 IU and 1,860 IU vitamin A and D/ kg dietary DM (SASD), respectively. Serum, liver, and intramuscular and subcutaneous adipose tissue retinol concentrations were decreased in (P < 0.001) in cattle fed the no supplemental vitamin A diets (NAND and NASD combined) compared with those consuming supplemental vitamin A (SAND and SASD combined) diets. In addition, intramuscular retinol concentration was 38% less than in the subcutaneous depot. Serum 25(OH)D3 concentrations were reduced (JP < 0.001 ) during the first 70 d when cattle were fed no supplemental vitamin D diets (NAND and SAND combined); however, liver 25(OH)D3 concentrations remained unchanged (P > 0.10) through d 184. Serum and liver 25(OH)D3 concentrations increased (P < 0.001) with vitamin D supplementation (NASD and SASD combined). The DMI, ADG, G:F, and morbidity were not affected (P > 0.10) by dietary concentration of vitamin A or D. There were vitamin A and D interactions (P < 0.03) for backfat thickness and USDA Yield grade. Cattle fed the NAND diet had greater (P < 0.03) Yield grades than other treatments because of greater (P < 0.005) 12th rib backfat thickness in NAND steers than the NASD and SAND steers. Vitamin D concentrations were attenuated and minimal carcass adiposity responses to vitamin D supplementation were observed. Feeding a diet without supplemental vitamin A increased (P < 0.05) Quality grades and marbling scores and tended (P = 0.06) to increase ether extractable lipid of the LM. As retinol and 25(OH)D3 concentrations in feedlot cattle declined as a result of a lack of dietary supplementation, adipose accretion increased, resulting in elevated Quality and Yield grades. Withdrawal of supplemental vitamin A, D, or both from the finishing diet of feedlot beef cattle had minimal impact carcass composition. [ABSTRACT FROM AUTHOR]

Twenty-four Dorper × Pelibuey ewe lambs initially weighing 25.1 ± 0.6 kg were used in a 34-d feeding experiment and after slaughter to evaluate the effect of zilpaterol hydrochloride (ZH) on feedlot performance, carcass characteristics, and wholesale cut yield. Ewe lambs were individually housed in pens, blocked by initial BW, and assigned randomly within BW blocks to 1 of 2 treatments: 1) control (no ZH) and 2) supplemented with ZH (10 mg/ewe lamb daily) during 32-d and a 2-d withdrawal preslaughter period. Feeding ZH increased (P < 0.01) final BW, ADG, and G:F of ewe lambs, whereas feed intake was unaffected (P = 0.80). Hot and cold carcass weights, dressing percentage, and conformation score were improved (P < 0.001) when ZH was fed. Likewise, LM area was 3.7 ± 0.41 cm2 larger (P < 0.001) for ZH than control ewe lambs. Feeding ZH did not affect (P ≥ 0.29) cooling loss, carcass length, fat thickness, or KPH. With exception of peritoneum (P < 0.001), head (P = 0.021), and neck (P < 0.001), ZH did not increase (P ≥ 0.12) noncarcass components or wholesale cut yield percentage. A trend to increase (P = 0.060) loin percentage from HCW was observed in lambs supplemented with ZH. In conclusion, feeding ZH to Dorper × Pelibuey ewe lambs improved feedlot performance and also some carcass traits (HCW, cool carcass weight, dressing percentage, and LM area) of economic importance; however, fat deposition was not affected by ZH. [ABSTRACT FROM AUTHOR]