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The objective was to examine the effects of metabolizable protein (MP) and ruminal-protected methionine supplementation on growth performance of Holstein steer calves during the initial feedlot growing phase (112 d). One hundred eighty Holstein steer calves (122 ± 7 kg) were blocked by weight and assigned to 30 pens (6 steers per pen). Five treatments were applied: 1) control, a diet based on steam-flaked corn containing urea and dry distillers grains plus solubles as supplemental N sources with no amino acid addition; 2) control diet plus blood meal supplementation; 3) diet from treatment 2, with 0.064% Smartamine M (70% methionine; Adisseo, Alpharetta, GA) supplementation; 4) diet from treatment 2 with 0.096% Smartamine M supplementation; 5) diet from treatment 2 with 0.128% Smartamine M supplementation. All diets were formulated to exceed the estimated MP requirements. The estimated metabolizable lysine, as well as methionine, was deficient in the control diet. Blood meal was added to the control diet to meet estimated lysine requirements (diet 2), the other diets had increasing concentrations of supplemental methionine. Supplemental MP enhanced (10%, P  0.10). Supplemental MP did not affect (P > 0.10) dry matter intake (DMI) during the first 56-d period; however, it tended to increase (P = 0.08) DMI during the subsequent 56-d period. Overall, supplemental MP or methionine had no appreciable effect (P > 0.10) on DMI. Supplemental MP improved (P  0.10) gain efficiency during the second 56-d period, although it tended to enhance (P = 0.08) estimated dietary NE. Supplemental methionine did not appreciably affect (P > 0.10) gain efficiency or estimated dietary NE. Therefore, adding MP to cover the estimated limiting amino acid supply in diets may enhance the gain efficiency and dietary energetics of growing Holstein calves. However, amino acid addition supplementation beyond the requirements may not produce extra productive performance of steer calves.

Beefalo is a fertile hybrid descendant of domestic cattle (Bos taurus) and American buffalo (Bison bison). Crossbred (¾Beefalo¼Nellore) beef cattle raised and finished in a feedlot or on pasture were evaluated for the effect of two ages (8 and 13 months) at castration on nutrient intake, performance, and carcass characteristics. In the feedlot, they received a total diet with a roughage:concentrate ratio of 55:45, and those kept on Brachiaria decumbens pastures were supplemented at 0.8% of body weight (BW) with the same concentrate based on corn and soybean meal (17.8% CP and 73% TDN). Thirty-six crossbred (¾ Beefalo ¼ Nellore) beef cattle with 209.2 ± 14.6 kg BW were used, which at weaning, at 8 months of age, were randomly divided into two groups, one of them destined to the feedlot system and the other group to the supplementation system on pasture. In each system (feedlot and pasture) the following treatments were distributed: castration at 8 months (at weaning, C8), castration at 13 months (C13), and non-castrated (NC), with six animals per treatment by system. All animals were slaughtered at 18 months of age. There was no significant interaction between the systems and castration ages for all variables studied. The averages of slaughter weight of feedlot animals were 475.6; 494.3 and 510.7 kg; and finished in pasture were 424.3; 428.0 and 418.7 kg for C8, C13, and NC treatments, respectively. The average subcutaneous fat thickness of the feedlot steers were 4.5, 3.5, and 1.3 mm, and for pasture-finished steers were 2.4, 1.6, and 1.8 mm for C8, C13, and NC treatments, respectively. Non-castrated animals have greater performance and carcass characteristics than castrated animals independent of the finished system. Animals non-castrated finished on Brachiaria grass pastures and slaughtered at 18 months of age require more intensive feeding management or even greater age at slaughter to obtain an ideal carcass finishing despite castration. [ABSTRACT FROM AUTHOR]

Simple Summary: There are increasing problems with both lameness and congestive heart failure in heavy, grain-fed steers and heifers. An inspection of hearts at the slaughter plant indicated that increasing numbers of these cattle have abnormally swollen hearts. This may increase death losses late in the feeding period. Lameness and hoof abnormalities in fed cattle have also increased. There is a possible relationship between both of these conditions and genetic selection for economically important meat traits. Both conditions seriously compromise animal welfare. Grain-fed steers and heifers have increasing problems with both lameness and congestive heart failure. Congestive heart failure used to be limited to cattle raised at high altitudes. It is now occurring at much lower elevations. An inspection of hearts at the slaughter plant indicated that some groups of grain-fed steers and heifers had abnormally swollen hearts in 34% of the animals. Congestive heart failure may also increase death losses in the late stages of the feeding program. Lameness has also increased to 8% of grain-fed steers and heifers arriving at U.S. slaughter plants. Twenty years ago, observations by the author indicated that lameness in fed cattle arriving at the slaughter plant was almost zero. There has also been an increasing occurrence of abnormal hoof structure and poor leg conformation. Genetic selection for rapid growth and a large ribeye may be associated with the increase in both of these problems. Lameness and heart problems severely compromise animal welfare. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the economic and financial viability of finishing of two sexes of Brazilian Somalis sheep in feedlot receiving diets with 0 and 15% reduction in the total digestible nutrients and crude protein contents. A completely randomized design was adopted, in a 2 × 2 factorial arrangement, with treatments consisting of two sexes (non-castrated males (21.13 ± 5.00 kg) and females (17.99 ± 3.79 kg) and two diets (0 and 15% reduction in the levels of total digestible nutrients and crude protein). Four simulations of productive scenarios were carried out: non-castrated males receiving the diet with 0% reduction; non-castrated males receiving the diet with 15% reduction; females receiving the diet with 0% reduction and females receiving the diet with 0% reduction, for a period of 70 days in feedlot. The highest costs of the system were with feeding and other costs, mainly the acquisition of animals. For both sexes, the 0% reduction diet showed the highest total cost, total revenue, break-even point. Non-castrated males fed a non-reduced diet and females fed a 15% reduction diet had higher net income, rate of return, total productivity, net present value, internal rate of return, profitability index and profitability rate. Less favorable situations were not profitable for any scenario. However, the increase in sales price favorability makes the activity viable. The reduction of total digestible nutrients and crude protein affects the economic and financial viability of Brazilian Somalis sheep. For non-castrated males it is recommended the diet without reduction and for females the diet with 15% reduction of nutrients. [ABSTRACT FROM AUTHOR]

Although bovine respiratory syncytial virus (BRSV) infection has been reported in cattle in Argentina, it has not been associated with pneumonia in Argentina. We report here 5 cases of bovine pneumonia associated with BRSV. Autopsies were performed on 35 beef cattle with gross and/or microscopic lesions of pneumonia from 3 commercial feedlots. Lung samples in 5 of 35 animals were BRSV-positive by reverse-transcription nested PCR. The lungs of 2 of these 5 animals were coinfected with Mannheimia haemolytica, and 1 with bovine viral diarrhea virus 1. Microscopically, the lungs of 3 of the 5 BRSV PCR-positive animals had fibrinosuppurative bronchopneumonia, with or without pleuritis; 2 of the 5 had interstitial pneumonia. We conclude that BRSV is part of the bovine respiratory disease complex in Argentina.

Simple Summary: A dynamic model was created to determine the nutritional requirements of lambs, aiming to simulate and describe their growth, nutrient requirements, and body composition. The model inputs include body mass, standard final mass, age, and dietary energy concentration. The results showed that the model accurately predicts the final body mass based on the inputs, with a coefficient of determination of 0.89 and a mean bias of 0.656 kg. The utility of this model extends to agricultural practitioners and livestock managers, providing valuable insights into forecasting final body mass and estimating the duration required to attain specific weights. Moreover, it serves as an educational tool elucidating the intricate interplay between nutrition, growth dynamics, and body composition in lambs. Thus, its implementation stands to enhance decision-making processes within feedlot lamb production, contributing to more informed and efficient management practices. A dynamic model has been developed to simulate aspects of feedlot lamb growth and body composition, including energy and protein requirements, growth rate, composition of gain, and body mass. Model inputs include initial body mass (kg), standard final mass (kg), age (days), and dietary energy concentration (Mcal·kg−1). The model was assessed as a decision support tool using a dataset of 564 individual measures of final body mass and diet energy. The simulations provide graphical and numerical descriptions of nutrient requirements, composition of gain, and estimates of animal performance over time. The model is accurate and precise, with a root mean squared error of 7.79% of the observed final body mass and a coefficient of determination of 0.89 when simulating the same variable. The model can be used as a reliable decision support tool to estimate final body mass and the days on feed required to reach a certain final mass with precision and accuracy. Moreover, the dynamic model can also serve as a learning tool to illustrate practical principles of animal nutrition, nutrient requirement relationships, and body composition changes. This model holds the potential to enhance livestock management practices and assist producers in making informed decisions about feedlot lamb production. [ABSTRACT FROM AUTHOR]

Simple Summary: Enhancing the energy density of lamb diets is a proven method to improve their productivity. While using carbohydrates for this purpose may seem intuitive, it can lead to undesirable shifts in ruminal metabolism, potentially triggering metabolic diseases. Hence, substituting carbohydrates with lipids is favored. Nevertheless, lipids, though effective, can also disrupt ruminal fermentation parameters. Among these lipids, soybean oil stands out for its positive impact on both beef and dairy cattle, leading to improved performance. In our study, we sought to assess the effects of soybean oil supplementation on performance, digestibility, feeding behaviour, and blood metabolites of feedlot lambs. Our findings indicate that the inclusion of soybean oil resulted in a linear reduction in nutrient intake, consequently lowering the average daily gain of the lambs. Additionally, soybean oil supplementation induced selective feeding behaviour among the lambs. Based on our observations, we recommend incorporating soybean oil into lamb diets at a maximum inclusion rate of 41 g/kg DM to optimize production parameters. The strategy implemented to adapt lambs to increasing levels of high-fat diet mitigated the detrimental effects of lipids on the rumen, with high-density energy intake being the constraining factor on performance. The objective of the current study was to evaluate the effects of soybean oil inclusion in diets on feeding behaviour, digestibility, performance, and blood metabolites of feedlot lambs. Forty non-castrated Santa Inês lambs with a mean age of 5 months and initial body weight of 34.88 ± 3.19 kg were used in a 40-day feeding trial. The lambs were distributed in five experimental diets with the inclusion of increasing soybean oil (SO) levels: 0, 30, 60, 90, and 120 g/kg DM. The SO inclusion promoted a linear reduction in DM intake (p < 0.001), crude protein (CP, p < 0.001), non-fibrous carbohydrates (NFC, p < 0.001), and total digestible nutrients (TDN, p = 0.004). There was an increasing quadratic effect on the intake of ether extract (EE; p = 0.002) and decreasing for neutral detergent fiber (p = 0.005). The soybean oil inclusion promoted the greater apparent digestibility of CP (p = 0.016), EE (p = 0.005), NDFom (p < 0.001), and TDN (p < 0.001); on the other hand, the apparent digestibility of NFC (p = 0.005) was decreased. The average daily gain decreased (p < 0.001) with SO inclusion. The SO inclusion increased feeding time (p = 0.004), reduced the efficiency of DM rumination (p = 0.001), and reduced the concentration of blood N-ureic (p < 0.001). Considering the productive parameters, SO can be included in diets and it is recommended that we include SO of up to 41 g/kg DM in diets for fattening lambs as the ideal maximum level. The strategy implemented to adapt lambs to increasing levels of high-fat diet mitigated the detrimental effects of lipids on the rumen, with high-density energy intake being the constraining factor on performance. [ABSTRACT FROM AUTHOR]

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]

It was hypothesised that hay type will affect feed intake and growth with significant interactions between breeds of sheep. Ten rams aged between 18 and 24 months and weighing 24.70, 25.50 and 24.75 each of Balami, Uda and Yankasa indigenous breeds of sheep in a complete randomised design with a 2 x 3 factorial arrangement were used. The rams were fed Brachiaria decumbens or Digitaria smutsii hay supplemented with concentrate at 1 % of their body weight. The trial lasted 90 days after 14 days adjustment period to the diets. Individual animal basal and supplementary concentrate feed intakes were recorded daily and liveweights were measured fortnightly. Data were analysed using SAS. Results of breed effect showed that Balami and Uda had significantly (P<0.05) higher values for most of the parameters measured while the effect of hay showed that rams fed Digitaria smutsii hay had significantly (P<0.05) higher feed intake and weight gain than their counterparts fed Brachiaria decumbens hay. The interaction effect also revealed that Balami had significantly (P<0.05) higher weight gain and feed conversion ratio while Yankasa had the lowest (P>0.05). It is therefore concluded from this study that feeding D. smutsii hay to rams gave better results than feeding B. decumbens hay. Hence, it is recommended that feeding D. smutsii hay can be effectively used in a feedlot production system for growing rams during a 90-day feedlot period. Furthermore, the detected interaction effect of hay type level with breed permits working choices of improving the ability to grow rams. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of feeding systems on the growth performance of Santa Inês x Dorper lambs, meat quality, fatty acid profile, and gene expression. Thirty lambs at an initial body weight of 22.6 ± 2.59 kg were randomly assigned to one of three feed systems: a grazing system with 1.2% body weight concentrate supplementation (GS); a feedlot system with 28% forage and 72% concentrate (FFC); or feedlot with 85% whole corn grain and 15% pellets (FHG). The lambs were slaughtered after 60 days of experiment. Average daily gain, glucose, and insulin concentration were higher for lambs on FHC than lambs on a GS feeding system. The fatty acid profile in the meat of the lambs fed GS showed a higher proportion of c9t11-C18:2, C20:5, C22:5, and C22:6 compared with FFC and FHC (p < 0.05). Meat tenderness was lower for lambs under FFC treatment compared with GS and FHG. FHG treatment provides better performance and higher deposition of lipid content in meat compared with GS and FHG. The expression of the genes SCD-1, SREBP1-c, and EVOL6 was greater in lambs undergoing GS and FHC treatments compared with FFC. Results of this research showed a reduced performance of grazing lambs compared with the feedlot system; however, it enhanced the fatty acid profile with increased levels of polyunsaturated acids and reduced n6/n3 ratio. [ABSTRACT FROM AUTHOR]

BackgroundCattle production in the United States is heavily supported by Latino/a workers. Beyond injury rates, our understanding of the health status of cattle feedyard workers is limited. The purpose of this study was to describe the health status and health care access among Latino immigrant cattle feedyard workers in the Midwest.MethodsA cross-sectional design using face-to-face structured interviews with Latino immigrant cattle feedyard workers in Kansas and Nebraska was conducted between May 2017 and February 2020.FindingsA total of 243 workers completed interviews; 91% were men. Over half (58%) had health insurance but few (36%) had a regular health care provider. Few chronic health conditions were reported despite most being overweight (53%) or obese (37%). The sample mean of sleep hours/24 hours was 7.1 ± 1.1. Problem drinking was moderate (42%), cigarette smoking was low (14%), and drug use was extremely low (

The increase in average global temperatures presents a challenge for the beef industry, especially in the feedlot sector where heat stress is a major animal welfare and economic concern. Shade is one of the most practical methods to mitigate heat stress in feedlot cattle. An experiment was conducted as a completely randomized design with 1 560 Bos indicus bulls (initial BW=287 kg) where three shade structure types were used to investigate the effects of different heat stress mitigation methods on cattle growth performance, environmental, and economic outcomes using live animal data, and a partial lifecycle assessment using the Integrated Farm System Model. The live animal portion of the experiment was done once a year over a 2-year period with three pen replications per treatment per year (n = 6 per treatment). Four shade structures used were conventional shade (SC; steel shade 1.8 m2 of shade/animal), double conventional shade (DS; steel shade 3.6 m2 of shade/animal), dome structures without fans (DSA; 8.5 m2/animal with 98% solar radiation blocked), and domes with fans (DCA; DSA plus three large sized low-speed fans). Each pen held 65 bulls in an area of 570 m2. Live animal data were analyzed as a completely randomized design using the GLM procedure of SAS (version 9.4) with shade type as fixed effect, pen as the experimental unit, and repetition (year) considered a random effect. Cattle housed under DCA had 22 and 20 kg heavier final body BW (P 0.05). Average daily gain, feed efficiency, and hot carcass weight were greater (P 0.05). When treatment results were extrapolated to the annual feedlot turnover of 209,700 animals, cattle in DSA and DCA versus SC and DS had 3–8% reductions in greenhouse gas and ammonia emission intensities. Compared to SC, DCA increased profitability by $29.66/animal, followed by DSA and DS with profit increases of $5.79 and $8.90/animal, respectively. Overall, the implementation of advanced shade structures improved cattle performance and profitability while reducing the environmental impact of beef production.

ABSTRACT The objective of this study was to assess the effects of high-concentrate diets with and without the inclusion of soybean hull (SH; 0 or 500.8 g/kg) plus corn (whole or ground) on the performance, morphometric traits, and nutritional and metabolic parameters of crossbred dairy calves. We also aimed to assess the costs associated with the experimental diets employed. Thirty-six male calves with an average weight of 89±18.6 kg and age of 3.5 months were allocated to four treatments, with nine replicates of one calf/pen, in a completely randomized experimental design for 198 days. The inclusion of the SH and the physical form of corn did not influence animal performance or morphometric measurements; however, SH inclusion increased the digestibility of neutral detergent fiber and the intakes of dry matter and neutral detergent fiber, but did not affect total digestible nutrient intake. The physical form of corn did not influence nutrient intake or digestibility, which resulted in similar performance across the animals. Blood glucose levels as well as alkaline phosphatase and creatinine remained elevated regardless of the diet. The use of SH reduced the total plasma cholesterol content, and there was an interaction between the physical form of corn and SH inclusion in relation to creatinine levels, which were higher when using diets with whole corn and SH. Although the inclusion of up to 500.8 g/kg of SH in the diet reduces feed efficiency, its use decreases the cost per kilogram of weight gain. Dairy calves can exhibit satisfactory production performance when fed alternative ingredients such as whole corn or SH, which have a lower cost than ground corn, traditionally used in diet formulations.

ABSTRACT The objective of this review was to identify, synthesize, and characterize, through an integrative approach, the main beef cattle finishing systems used in Brazilian scientific research. A review protocol was developed, and the search terms were based on the PVO strategy to formulate the study's guiding question: study population (P) consists of beef cattle, the variables of interest (V) were the finishing systems adopted in the studies with cattle in Brazil, and the outcomes (O) were the characteristics of the finishing systems. The following guiding question was formulated: What are the major beef cattle finishing systems used in scientific research in Brazil? The databases used were SCOPUS, Web of Science, and Science Direct. 1,388 studies were found, 1,163 of which were scientific articles. However, 33 publications were selected for data extraction. The studies covered different regions of Brazil: Southeast (14), South (10), Midwest (8) and Northeast (1). The confinement finishing system was the strategy used in 63.4% of the experiments and 24.2% of pasture systems with supplementation. In 81.1% of the studies, the pure Nellore breed or crossed with other breeds was used. Scientific research on cattle finishing in Brazil focuses on confinement systems.

The objective of this study was to evaluate the influence of supplemental flavomycin on cattle growth performance, carcass characteristics, diet digestibility, and ruminal fermentation characteristics of calf-fed Holstein steers. One hundred Holstein steers (123 ± 7 kg) were balanced by weight and assigned to 20 pens. Dietary treatments consisted of a steam flaked corn-based diet supplemented with (dry matter basis): 1) control, no feed additive; 2) 6.6 mg/kg flavomycin; 3) 13.2 mg/kg flavomycin, and 4) 30 mg/kg monensin (MON). There were no treatment effects (P ≥ 0.17) on live weight, average daily gain (ADG), and gain efficiency. Flavomycin did not affect dry matter intake (DMI; P ≥ 0.24). Flavomycin supplementation did not affect (P ≥ 0.37) the ratio of observed vs. expected DMI. However, MON decreased (P = 0.02) observed vs. expected DMI by 3.7%. There were no treatment effects (P ≥ 0.44) on ruminal pH or temperature. Flavomycin did not affect (P ≥ 0.13) carcass characteristics and liver abscess among steers. Four Holstein steers (463 ± 20 kg) with ruminal cannulas were used in 4 × 4 Latin square experiment to study treatment effects on site and extent of digestion, ruminal pH, and volatile fatty acid (VFA) molar proportions. Dietary treatments were the same as experiment 1. Flavomycin tended to increase (linear effect, P = 0.07) ruminal organic matter (OM) digestion, associated with increased (linear effect, P < 0.01) ruminal starch digestion. Supplementing flavomycin at 13.2 mg/kg decreased net microbial N synthesis (quadratic effect, P = 0.03). Compared with control, MON tended to increase (P = 0.10) ruminal neutral detergent fiber (NDF) digestion and increased (P < 0.01) ruminal starch digestion. Monensin did not affect (P = 0.39) net microbial N synthesis, but decreased (P = 0.01) ruminal degradation of feed nitrogen (N). There were no treatment effects (P > 0.10) on total tract apparent digestion of DM, OM, NDF, and starch. Flavomycin decreased ruminal pH (quadratic effect, P < 0.01) measured 4 h postprandial. Compared with control, MON increased ruminal pH (P = 0.03). Flavomycin increased (linear effect, P = 0.03) ruminal propionate molar proportion and decreased (linear effect, P ≤ 0.04) ruminal molar proportions of acetate and butyrate, and decreased (linear effect, P = 0.02) acetate:propionate molar ratio and estimated methane production. We conclude that supplementing flavomycin at 6.6 or 13.2 mg/kg had no major effects on cattle growth performance, carcass characteristics, diet digestibility, and ruminal fermentation characteristics.

Evaluation of the effects of feeding NutraGen supplement (NutraGen, NTG; Phibro Animal Health, Teaneck, NJ, USA) on growth performance, energetic efficiency, carcass characteristcs, and characteristics of digestion in calf-fed Holstein steers fed a conventional growing-finishing diet. Trial 1 evaluated growth performance, dietary energetics and carcass characteristics. Two hundred Holstein steer calves (134 ± 5 kg) were blocked by initial body weight (BW) and randomly assigned to 40 pens (5 steers/pen). Dietary treatments consisted of a steam-flaked corn-based growing-finishing diet supplemented with 0, 0.2, 0.4, or 0.6% NTG (DM basis). In trial 2, four Holstein steers (170 ±6 kg) with cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square experiment to evaluate digestibility and ruminal characteristics using the treatments from trial 1. Compared to non-supplemented cattle, NTG increased BW (2.0%, P = 0.02) and tended to increase ADG (3.6%, P = 0.07) during the initial 56 d period. However, there were no treatment effects on overall growth performance and efficiency of dietary energy utilization after the first 56 days (P > 0.10). Supplementation of NTG increased (linear effect; P ≤ 0.03) longissimus muscle area and kidney, pelvic, and heart fat. There was no effect (P ≥ 0.05) of NTG supplementation on other carcass characteristics, liver abscess incidence, or liver abscess scars. Supplementation decreased the molar proportion of ruminal propionate (P = 0.05) and tended to increase acetate:propionate molar ratio (P = 0.09). However, there was no effect of NTG supplementation on ruminal and total tract diet digestion. NTG increased performance of Holstein steers during the first 56 d on feed in the feedlot. In addition, the steers had an increase in KPH fat and LM area, indicating that the additive induced change in metabolism of the steers.

Feed additives such as monensin (MON) and virginiamycin (VM) are commonly utilized in feedlot diets to enhance rumen fermentation. Nevertheless, the precise effects of combining MON and VM during specific feedlot periods and the advantages of this combination remain unclear. This study was designed to investigate the effects of withdrawal of MON when associated with VM during the adaptation and finishing periods on ruminal metabolism, feeding behavior, and nutrient digestibility in Nellore cattle. The experimental design was a 5 × 5 Latin square, where each period lasted 28 days. Five rumen-cannulated Nellore yearling bulls were used (414,86 ± 21,71 kg of body weight), which were assigned to five treatments: (1) MON during the entire feeding period; (2) VM during the entire feeding period; (3) MON + VM during the adaptation period and only VM during the finishing period 1 and 2; (4) MON + VM during the entire feeding period; (5) MON + VM during the adaptation and finishing period 1 and only VM during the finishing period 2. For the finishing period 1, animals fed T3 had improved potential degradability of dry matter (p = 0.02). Cattle fed T3 and T5 had the highest crude protein degradability when compared to animals receiving T2 (p = 0.01). Animals fed T2 and T3 had reduced the time (p < 0.01) and area under pH 6.2 (p = 0.02). Moreover, animals fed T4 had greater population of protozoa from the genus Diplodinium (p = 0.04) when compared to those from animals fed T2, T3 and T5. For the finishing period 2, animals fed T3 had greater starch degradability when compared to animals receiving T4 and T5 (p = 0.04). Animals fed T3, T4 and T5 had increased the duration of time in which pH was below 5.6 (p = 0.03). The area under the curve for ruminal pH 5.2 and pH 5.6 was higher for the animals fed T3 (p = 0.01), and the area under pH 6.2 was higher for the animals fed T3 and T5 (p < 0.01) when compared to animals receiving T2. There is no substantial improvement on the rumen fermentation parameters by the concurrent utilization of MON and VM molecules, where the higher starch and protein degradability did not improve the rumen fermentation. [ABSTRACT FROM AUTHOR]

A determination of how the amount of allotted feedlot living space influences both production indicators as well as carcass and meat quality traits obtained from Holstein steers was performed by forming two treatment groups, T14: 65 steers/pen (14 m²/head of space allowances) and T16: 57 steers/pen (16 m²/head of space allowances), with five replications each treatment. The average arrival weight 238 ± 0.74 kg. During the fattening period the cattle was feed twice a day with commercial diets. The steers were slaughtered after a 261-d period. At the moment of the first reimplant a greater average body weight was found in T16 vs T14 (384.25 vs 378.38 kg; P<0.05) and the difference continued until day 261 (612.35 vs 595.54 kg; P<0.05); regarding ADG, hot carcass weight and cold carcass weight the result were: 1.50 vs 1.46 kg (P<0.05), of ADG kg/d; 367.34 vs 360.35 kg (P<0.05) and 366.68 vs 358.78 kg (P<0.05). No difference between treatments were found in dorsal fat, marbling, pH and meat color. The results suggest that an increase from 14 m²/animal to 16 m²/animal improves the production results as well as the hot and cold carcass weight, with no effect on the quality traits of the carcass and beef. [ABSTRACT FROM AUTHOR]

Antimicrobials are crucial for treating bovine respiratory disease (BRD) in beef feedlots. Evidence is needed to support antimicrobial use (AMU) decisions, particularly in the early part of the feeding period when BRD risk is highest. The study objective was to describe changes in prevalence and antimicrobial susceptibility of BRD bacterial pathogens at feedlot processing (1 day on feed (1DOF)), 12 days later (13DOF), and for a subset at 36DOF following metaphylactic antimicrobial treatment. Mixed-origin steer calves (n = 1599) from Western Canada were managed as 16 pens of 100 calves, receiving either tulathromycin (n = 1199) or oxytetracycline (n = 400) at arrival. Deep nasopharyngeal swabs collected at all time points underwent culture and antimicrobial susceptibility testing (AST). Variability in the pen-level prevalence of bacteria and antimicrobial susceptibility profiles were observed over time, between years, and metaphylaxis options. Susceptibility to most antimicrobials was high, but resistance increased from 1DOF to 13DOF, especially for tetracyclines and macrolides. Simulation results suggested that sampling 20 to 30 calves per pen of 200 reflected the relative pen-level prevalence of the culture and AST outcomes of interest. Pen-level assessment of antimicrobial resistance early in the feeding period can inform the evaluation of AMU protocols and surveillance efforts and support antimicrobial stewardship in animal agriculture. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the replacement of barley-based ingredients with short-season high-moisture corn products on steer growth performance and carcass characteristics. Over 2 years, 320 beef steers (528�±�36.2�kg initial body weight) were assigned to 32 pens (4 pens/treatment/year). Treatments were finishing diets that contained dry-rolled barley grain and barley silage (BGBS; control), barley grain and corn silage (BGCS), high-moisture shelled corn and barley grain with barley silage (HCBS), or snaplage (included as a silage and grain source) with barley grain (SNAP). Steers were fed for 99 days and 72 days in years 1 and 2, respectively. Steers fed BGCS did not differ (P�≥�0.13) from BGBS for dry matter intake, average daily gain, gain:feed, or carcass characteristics. Steers fed HCBS had greater (P�≤�0.05) hot carcass weight and dressing percentage than BGBS. A lesser (P�=�0.02) proportion of steers fed SNAP had severe liver abscesses than BGBS. We concluded that corn silage can replace barley silage, 50% replacement of barley grain with high-moisture shelled corn may improve hot carcass weight, and replacement of barley silage and some barley grain with snaplage decreases the proportion of cattle with severe liver abscesses at slaughter. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the performance, intake, digestibility, ruminal parameters, carcass traits, and the yield of commercial cuts of Santa Ines (SI) and Rabo Largo (RL) breeds fed diets with high or low roughage-to-concentrate ratio (R:C) under a tropical climate. Twenty lambs from each breed were individually housed in covered pens and fed the experimental diets for 58 days. The diets were formulated to meet the growth requirements of lambs with a roughage-to-concentrate ratio of 70:30 and 30:70. Significant interactions of breed × diet for nutrient intake were observed (P < 0.05), with SI lambs fed low R:C diet showing higher intake of dry matter, organic matter, crude protein, and total carbohydrates compared to RL lambs fed the same diet. SI lambs fed high R:C diet had higher intake of neutral detergent fiber than RL lambs (P < 0.05). SI lambs displayed better average daily gain and feed efficiency, regardless of diet (P < 0.05). Carcass traits and gastrointestinal components were influenced by breed and diet (P < 0.05). SI lambs fed low R:C diet showed higher subcutaneous fat thickness and better carcass finishing compared to RL lambs (P < 0.05). SI breed lambs exhibited better growth performance, carcass traits, and gastrointestinal characteristics, even when fed diets with a high roughage-to-concentrate ratio. [ABSTRACT FROM AUTHOR]

The use of high-grain diets in feedlots is associated with the development of acidosis and ruminitis, which can lead to the occurrence of liver abscesses (LAs). However, the effect of LA on carcass traits is not well known. This study assessed the effects of LA on the performance and carcass traits of beef cattle. Nine peer-reviewed publications with forty-seven treatment means were included in the data set. The effects of the LA were evaluated by examining the weighted mean difference (WMD) between LA (animal with LA) and control treatment (animal without LA). Heterogeneity was explored by meta-regression, followed by a subgroup analysis of the scores and percentages of liver abscess and concentrate level in the feedlot diet. Animals affected by LA showed a reduction in dry matter intake (−1.03%) and feed efficiency (−1.82%). Animals with an LA score of "A" (one or two small abscesses) exhibited a decrease in carcass weight (WMD = 3.41 kg; p = 0.034) and ribeye area (WMD = −1.37 cm2; p = 0.019). When assessing the impact of LA on carcass traits, the most reliable finding indicates a 1.21% reduction in the ribeye area, with no adverse effects observed on subcutaneous fat thickness or the marbling score in the carcass. [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]

ABSTRACT The objective of this study was to evaluate the effects of an essential oil blend (EO), based on cinnamaldehyde and diallyl disulfide, associated or not with antibiotics on intake and nutrient digestibility, ingestive behavior, rumen fermentation, ruminal microbial synthesis, and blood metabolites of feedlot cattle fed a no-forage diet. The study was carried out as a Latin Square with five treatments consisting of a blend of essential oil (EO), monensin (MON) and virginiamycin (VM), both separately and combined as follows: CON (monensin at 30 mg kg–1 DM), VM (virginiamycin at 25 mg kg–1 DM and monensin at 30 mg kg–1 DM), MEO25 (monensin at 30 mg kg–1 DM and EO at 25 mg kg–1 DM), MEO35 (monensin at 30 mg kg–1 DM and EO at 35 mg kg–1 DM) and EO35 (blend of EO at 35 mg kg–1 DM). There were no effects from additives and their combinations on the intake and apparent digestibility of nutrients or ingestive behavior. Furthermore, treatments did not modify the ruminal pH, nor the concentration of short-chain fatty acids and ammonia, nor the microbial protein synthesis. Blood glucose concentration was higher 4 h after morning feeding for all treatments. There was a significant contrast between the VM and EO for the blood concentration of D-Lactate and L-Lactate. There was no difference between the additives in the concentration of cortisol metabolites in the feces. The blend of essential oil studied, containing cinnamaldehyde and diallyl disulfide, associated or not with antibiotics, does not change the nutritional parameters nor the metabolism of feedlot cattle fed a no-forage diet.

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.

The use of high-grain diets in feedlots is associated with the development of acidosis and ruminitis, which can lead to the occurrence of liver abscesses (LAs). However, the effect of LA on carcass traits is not well known. This study assessed the effects of LA on the performance and carcass traits of beef cattle. Nine peer-reviewed publications with forty-seven treatment means were included in the data set. The effects of the LA were evaluated by examining the weighted mean difference (WMD) between LA (animal with LA) and control treatment (animal without LA). Heterogeneity was explored by meta-regression, followed by a subgroup analysis of the scores and percentages of liver abscess and concentrate level in the feedlot diet. Animals affected by LA showed a reduction in dry matter intake (−1.03%) and feed efficiency (−1.82%). Animals with an LA score of “A” (one or two small abscesses) exhibited a decrease in carcass weight (WMD = 3.41 kg; p = 0.034) and ribeye area (WMD = −1.37 cm2; p = 0.019). When assessing the impact of LA on carcass traits, the most reliable finding indicates a 1.21% reduction in the ribeye area, with no adverse effects observed on subcutaneous fat thickness or the marbling score in the carcass.

The evolution of ruminants was largely influenced by the symbiotic relationship between ruminal microbiota and the host. Within the rumen, these microorganisms degrade feedstuffs to produce organic acids and synthesize microbial protein, as energy and protein source for ruminants, respectively. This process is accelerated when these animals are transferred to feedlot diets. This review brings the most current studies that reported the most used nutritional managements in this transition process, in order to avoid metabolic disturbances, in which rumen development is a fundamental point. Also, this review brings the main biomolecules used as feed additive, which can in the help control of fermentation processes in order to minimize energetically inefficient processes within the rumen, as well as losses by excretion to the environment, which are widely questioned by be environmental pollutants. Furthermore, the main results of research on animal performance in response to these additives are reported, supplemented alone or associated with different feed additives when used on diets with high grain contents, as well as evaluating the potential of additives as antibiotics alternatives, a fact that has been discussed and is worrying since the use of ionophores or non-ionophores antibiotics represent practically the totality of feedlot diets.

Grain-fed steers and heifers have increasing problems with both lameness and congestive heart failure. Congestive heart failure used to be limited to cattle raised at high altitudes. It is now occurring at much lower elevations. An inspection of hearts at the slaughter plant indicated that some groups of grain-fed steers and heifers had abnormally swollen hearts in 34% of the animals. Congestive heart failure may also increase death losses in the late stages of the feeding program. Lameness has also increased to 8% of grain-fed steers and heifers arriving at U.S. slaughter plants. Twenty years ago, observations by the author indicated that lameness in fed cattle arriving at the slaughter plant was almost zero. There has also been an increasing occurrence of abnormal hoof structure and poor leg conformation. Genetic selection for rapid growth and a large ribeye may be associated with the increase in both of these problems. Lameness and heart problems severely compromise animal welfare.

Context. Wagyu Feeder Check is a genomic-based tool designed to provide genomic estimated breeding values (GEBV) for five feedlot growth and carcase traits. At present, Wagyu Feeder Check is based on a reference population of 8316 genotyped and phenotyped Australian fullblood (FB; N = 2120) Wagyu and Wagyu-crossed (XB; N = 6196) cattle, principally Wagyu × Angus F1 animals. Aims. We provide technical details behind the development of the Wagyu Feeder Check and validate the ability of its GEBV to predict differences in performance of Wagyu cattle in daily weight gain at feedlot, carcase weight, carcase eye muscle area, carcase marbling score and carcase rump fat at the P8 site. Methods. Data supplied from eight commercial supply chains across Australia was used to generate GEBV using mixed-model equations that incorporated a genomic relationship matrix build with 82 504 autosomal markers. The bias, dispersion, and accuracy of the GEBV were evaluated using a four-way cross-validation scheme where, in each turn, the phenotypes from a random 1549 (or 25%) XB cattle were set as missing. Key results. The genomic estimate of the Wagyu content in the FB and XB population averaged 99.12% and 59.55%, respectively, and with most of the non-Wagyu content associated with Angus. The estimates of heritability (± s.e.) were 0.497 ± 0.016, 0.474 ± 0.004, 0.347 ± 0.014, 0.429 ± 0.003 and 0.422 ± 0.003 for daily weight gain at feedlot, carcase weight, eye muscle area, marbling and rump fat, respectively. Averaged across the four XB validation populations, the accuracy of GEBV was 0.624, 0.634, 0.385, 0.620, and 0.526 for the same set of traits. Conclusions. Genomic predictions generated by Wagyu Feeder Check can predict differences in feedlot and carcase performance of Australian Wagyu cattle. Given the large content of Angus in the XB population, further research is required to determine the predictive ability of GEBV in Wagyu × Bos indicus and Wagyu × dairy animals. Implications. Commercial feedlot operators finishing animals with a strong Wagyu breed component will benefit from using Wagyu Feeder Check for decision making. [ABSTRACT FROM AUTHOR]

The objective of this work was to analyze the effects of dentition and finishing degree on weight and carcass yield of predominantly Aberdeen Angus cattle, finished in feedlot. The independent variables evaluated were dentition and degree of finishing. The dependent variables evaluated were cold carcass weight (PCF), cold carcass yield related to farm weight (RFZ) and cold carcass yield related to slaughterhouse weight (RFG). Data of 7,171 bovines, castrated steers and heifers, finished in feedlot of the slaughterhouse that provided the data were considered. The feedlot and slaughterhouse are located in Rio Grande do Sul state, Brazil, and the data were collected during the years 2020 and 2021. These were analised to interaction and linear regression. For steers and heifers, the regression equations of the dependent variables as a function of dentition are significant, presenting a positive estimator for PCF. For RFZ the equation was not significant for steers, and for RFG the equation was not significant for the heifers. The equations of the variables in relation to the finishing degree were significant, presenting a positive estimator for steers and heifers. The increase in dentition increases PCF in both males and females, but decreases RFZ in females, not changing in steers. The GFR decreases in males with advancing maturity, but does not change in females. The increment in the finishing degree increases the PCF, and the yields of cold carcass, RFZ and RFG. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the impact of increasing levels of heat-treated soybean in the diet of crossbred cattle during the finishing phase on nutrient intake and digestibility, ruminal parameters, digesta passage rate, nitrogen balance, and microbial protein synthesis. Five steers, crossbred 7/8 Jersey x Zebu, fitted with rumen cannulas and with an average weight of 350 ± 50 kg, were utilized. The experimental treatments consisted of 0, 7, 14, 21, and 28% inclusion of heat-treated soybean in the total diet dry matter. The animals were randomly allocated in a 5 × 5 Latin square design. Evaluation of the animals took place over five experimental periods, each lasting 20 days. During each experimental period, the first 15 days were allocated for animal adaptation to the experimental diets, followed by five days of data collection. No significant differences were observed among the diets in terms of dry matter intake (average of 6.57 kg day−1; P = 0.615) and organic matter intake (average of 6.23 kg day−1; P = 0.832). However, heat-treated soybean had a significant impact on the digestibility of dry matter (P = 0.02), organic matter (P = 0.01), crude protein (P < 0.01), and neutral detergent fiber (P < 0.01). There was no observed change on microbial protein synthesis (average of 409.6 g day−1) in animals with the inclusion of heat-treated soybean in the diets. With each 1% inclusion of heat-treated soybean in the cattle diet, there was an increase of 0.00754 units in ruminal pH values and a reduction of 0.75839 mg dL−1 in ruminal ammoniacal nitrogen values. This study suggests that heat-treated soybean can be included in up to 15% of the dry matter in diets for finishing feedlot cattle. [ABSTRACT FROM AUTHOR]

The evolution of ruminants was largely influenced by the symbiotic relationship between ruminal microbiota and the host. Within the rumen, these microorganisms degrade feedstuffs to produce organic acids and synthesize microbial protein, as energy and protein source for ruminants, respectively. This process is accelerated when these animals are transferred to feedlot diets. This review brings the most current studies that reported the most used nutritional managements in this transition process, in order to avoid metabolic disturbances, in which rumen development is a fundamental point. Also, this review brings the main biomolecules used as feed additive, which can in the help control of fermentation processes in order to minimize energetically inefficient processes within the rumen, as well as losses by excretion to the environment, which are widely questioned by be environmental pollutants. Furthermore, the main results of research on animal performance in response to these additives are reported, supplemented alone or associated with different feed additives when used on diets with high grain contents, as well as evaluating the potential of additives as antibiotics alternatives, a fact that has been discussed and is worrying since the use of ionophores or non-ionophores antibiotics represent practically the totality of feedlot diets. [ABSTRACT FROM AUTHOR]

Feedlot cattle are at times exposed to high environmental temperatures. Faecal cortisol metabolites were related to possible indicators of heat stress that could be measured under field conditions: respiratory dynamics (respiration rate), body surface temperature and adaptive behaviours, such as water consumption, posture (standing, lying), and activity (eating, drinking and rumination). Twelve (12) yearling Black Angus steers were divided into two treatment groups: a hot treatment (HOT; n = 6) and a thermoneutral-treatment (TN; n = 6) and individually housed in a climate-controlled facility at The University of Queensland, Australia. In the TN treatment, all animals were exposed to an ambient temperature of 20.34 ± 0.25 °C, relative humidity 71.51 ± 3.26% and Temperature humidity index (THI) 66.91 ± 0.33 throughout. In the HOT treatment group, environmental conditions were exposed to different climatic phases from thermoneutral to hot conditions, where they remained for 7 d, and then returned to TN conditions in the recovery period. The dry bulb ambient temperature (TA) and relative humidity (RH) in the pens of cattle in the HOT treatment were increased from 28 °C (daily maximum ambient temperature) and 45% RH at 0700 h to a daily maximum TA and RH of 35 °C (daily maximum ambient temperature) and 50% (THI 77) at 1100 h, which was maintained until 1600 h, after which it declined until it reached the baseline at 2000 h. In both treatments, there was a significant decrease in faecal cortisol metabolite concentration from the start to the end of the experiments they adapted to the experimental facility. The concentration of faecal cortisol metabolites was greater in the HOT treatment, compared to the TN treatment during the heat exposure period, but there was no difference in the transition or recovery periods. Respiration rate was greater in the HOT treatment during heat exposure, and it increased with ambient dry bulb temperature above 26 °C, the latter being the upper critical temperature. Although positive correlations were detected between faecal cortisol metabolites and body surface temperature measurements, particularly the shoulder and rump, as well as standing time, panting score and drinking, a stepwise regression found that faecal cortisol metabolites were only significantly correlated with one variable, respiration rate. It is concluded that respiration rate is the best indicator of the stress induced by hot conditions for cattle.

Feed additives such as monensin (MON) and virginiamycin (VM) are commonly utilized in feedlot diets to enhance rumen fermentation. Nevertheless, the precise effects of combining MON and VM during specific feedlot periods and the advantages of this combination remain unclear. This study was designed to investigate the effects of withdrawal of MON when associated with VM during the adaptation and finishing periods on ruminal metabolism, feeding behavior, and nutrient digestibility in Nellore cattle. The experimental design was a 5 × 5 Latin square, where each period lasted 28 days. Five rumen-cannulated Nellore yearling bulls were used (414,86 ± 21,71 kg of body weight), which were assigned to five treatments: (1) MON during the entire feeding period; (2) VM during the entire feeding period; (3) MON + VM during the adaptation period and only VM during the finishing period 1 and 2; (4) MON + VM during the entire feeding period; (5) MON + VM during the adaptation and finishing period 1 and only VM during the finishing period 2. For the finishing period 1, animals fed T3 had improved potential degradability of dry matter (p = 0.02). Cattle fed T3 and T5 had the highest crude protein degradability when compared to animals receiving T2 (p = 0.01). Animals fed T2 and T3 had reduced the time (p

In calf-fed Holstein steers, the early growing phase is characterized by very high relative dry matter intake (DMI) accompanied with lower-than-expected efficiency of energy utilization. Although fat is commonly supplemented in growing-finishing diets, the comparative feeding value has not been investigated during the initial receiving-growing period. Eighty-four Holstein calves (127.7 ± 2.1 kg body weight) were used to evaluate the effects of including 3.5% of supplemental yellow grease (YG) in the diet on characteristics of growth performance and dietary energy utilization of calves during the early growth phase. Morbidity and mortality were not affected by dietary treatments. Yellow grease supplementation did not affect DMI, but tended to increase average daily gain (4.6%; P = 0.07), and increased (P ≤ 0.03) gain efficiency (5.8%) and dietary net energy for maintenance (NEm) and gain (NEg) by 4.1% and 5.3%, respectively. Based on performance data, the estimated NE value of supplemental YG was 4.67 and 3.68 Mcal/kg for NEm and NEg, respectively. These values are consistent with current tabular values assigned for vegetable oils (4.75 and 3.51 Mcal/kg), but markedly less (16.6%) than NEm value assigned for YG (5.60 Mcal NEm/kg; NASEM, 2016. Nutrient requirements of beef cattle. 8th ed. Washington (DC): National Academy Press.).

Bans on the use of ionophores in several regions of the world has led to a need to identify alternative feed additivies to be added in cattle diets. Essential oil blends have been identified as a potential alternative to ionophores in feedlot diets. The objective of this study was to evaluate the effects of a supplemental a blend of essential oils and 25-hydroxyvitamin D3 on growth performance, energetic efficiency, and carcass characteristics in calf-fed Holstein steers. Ninety Holstein steer calves (123 ± 7 kg; 4 months old) were randomly assigned to 18 pens (5 steers/pen; 6 pens/treatment). Dietary treatments consisted of a steam-flaked corn-based diet supplemented with (DM basis): (1) no additives (CON); (2) 30 mg/kg DM of monensin (MON); (3) 200 mg/kg DM of a mixture of essential oils plus 25-hydroxyvitamin D3 (EO+HYD). There were no treatment effects (P > 0.05) on initial, intermediate and final cattle live weight; moreover, cattle had similar (P > 0.05) average daily gain (ADG) and dry matter intake (DMI) among dietary treatments. However, during the first 112 days of feed, calf-fed Holstein steers supplemented with EO+HYD had a greater (P ≤ 0.05) gain to feed ratio (G/F) than cattle fed the control diet but similar (P > 0.05) G/F to cattle supplemented with MON. However, there was no effect (P > 0.05) of dietary treatments on 112 to 286 d and the overall G/F ratio of calf-fed Holstein steers. Calf-fed Holstein steers supplemented with EO+HYD had greater (P ≤ 0.05) estimated net energy for maintenance (NEm) and net energy for gain (NEg) based on cattle growth performance than cattle fed the CON diet. Cattle supplemented with MON had an intermediate and similar (P > 0.05) NEm and NEg compared to the other two dietary treatments. However, when observed vs. expected NEm and NEg were calculated, cattle supplemented with MON and EO+HYD had greater efficiency of dietary energy utilization than cattle fed the CON diet. Calf-fed Holstein steers supplemented with MON had greater (P < 0.05) fat thickness than EO+HYD supplemented steers, and both were intermediate (P ≥ 0.05) to that of cattle fed the CON diet. There were no other effects (P > 0.05) on kidney, pelvic and heart fat, longissimus area, marbling score, and retail yield. The health status of cattle and liver abscesses or liver scars at slaughter were similar (P > 0.05). We conclude that supplementing calf-fed Holstein steers with MON or EO+HYD for over 285 days increased dietary net energy utilization for maintenance and gain of the diet by 3 and 4%, respectively, compared to non-supplemented steers.

In experiment 1, 150 calf-fed Holstein steers (119 ± 6 kg) were used to evaluate the effects of level of supplemental condensed tannin (0, 14, and 28 g/kg diet DM) in a conventional steam-flaked corn-based growing-finishing diet on feedlot growth performance. There were no treatment effects on growth performance during the initial 56-d period. However, during the subsequent 56-d period, supplemental condensed tannin tended to increase average daily gain (ADG; linear effect, P = 0.09). The increase in ADG was consistent with the tendency for increased dry matter intake (DMI; linear effect, P = 0.08). Hence, differences in gain efficiency during the second 56-d period were not appreciably affected (P = 0.80). Supplemental condensed tannin did not affect overall (112-d) ADG, DMI, gain efficiency, or dietary NE. In a second experiment, six Holstein steers (179.4 ± 7.9 kg) with cannulas in the rumen and proximal duodenum were used in a replicated 3 × 3 Latin square design to evaluate treatment effects on characteristics of ruminal and total tract digestion. Treatments were the same as in Trial 1. Tannin supplementation decreased (linear effect, P = 0.03) ruminal OM digestion and tended to decrease (linear effect, P = 0.06) ruminal feed N degradation. Tannin supplementation decreased (linear effect, P = 0.03) ruminal pH, but did not affect (P > 0.20) ruminal molar proportions of volatile fatty acids and estimated methane production. In current study, supplemental tannin had marginal effects on overall growth performance of calf-fed Holstein steers, but reduced ruminal, postruminal, and total tract nitrogen digestion.

ObjectiveEvaluate the effect of arrival weight on feedlot growth performance and carcass characteristics of Holstein steers of similar age.Material and methodsThree hundred calf-fed Holstein steers (age 113 ± 1-day) were distributed in a completely randomly unbalanced design and divided into five categories (105, 112, 117, 123, and 129 kg) of shrunk initial weight (SIW). Calves were weighed on days 1, 112, 224, and 361. Calves were fed steam-flaked corn-based diets. Growth performance and dietary energy were evaluated for each period and the study as a whole (1-361-day).ResultsDuring the rearing period, average daily gain (ADG) increased (linearly effect, p < 0.01) with increasing birth weight. Birthweight was positively associated (p < 0.05) with feedlot arrival weight (R 2 = 0.47) and final harvest weight (R 2 = 0.36). Overall ADG increased (p < 0.01) with increasing SIW. Dry matter intake increased linearly during the first 224-day but quadratically during the last 137 days. Overall, there was a quadratic effect (p < 0.05) of SIW on gain-to-feed and observed-to-expected dietary NE, with lower efficiencies (4%) for steers in both the lightest and heaviest SIW. Hot carcass weight, Longissimus muscle area, marbling score, and fat thickness increased (linear effect, p ≤ 0.03) as SIW increased, whereas kidney-pelvic-heart fat and yield-grade were unaffected.ConclusionsThe initial arrival weight influences the growth performance, energetic efficiency, and carcass characteristics of Holstein steers of similar age. The effect is more pronounced in the lighter (

One hundred sixty-eight Holstein steer calves (133.4 ± 7.9 kg) were used to evaluate the influence of virginiamycin (VM) supplementation on cattle growth performance and liver abscess incidence, and the effect of feeding 100% vs. 87% of metabolizable protein (MP) requirements during the initial 112 d on growth performance, efficiency of energy utilization, and carcass characteristics. Steers were balanced by weight and assigned to 28 pens (6 steers/pen). During the initial 112-d feeding period, dietary treatments consisted of two levels of MP (100% vs. 87% of expected requirements) supplemented with or without 22.5 mg/kg VM in a 2 × 2 factorial arrangement. There were no VM × MP supplementation interactions (P ≥ 0.14) on any of the parameters measured in both experiments. Calf-fed Holstein steers supplemented with VM increased (P ≤ 0.03) overall average daily gain (ADG), feed efficiency (G:F), observed/expected net energy (NE) values for maintenance and gain, and final body weight (BW). Cattle fed VM also increased (P ≤ 0.04) carcass weight, dressing percent, and longissimus muscle area. However, there was no effect (P ≥ 0.22) of VM supplementation on any other carcass characteristics. Calf-fed Holstein steers fed 100% MP requirements during the initial 112-d feeding period had greater (P ≤ 0.02) ADG, G:F, observed/expected NE values for maintenance and gain, and live BW compared with steers fed 87% of the expected MP requirements. However, there was no effect (P ≥ 0.17) of MP supply during the initial 112-d period on overall (342 d) growth performance measurements. The incidence of liver abscesses was low (averaging 7.7%) and not affected by dietary treatments. We conclude that, independent of MP supplies, supplemental VM enhances overall growth performance and efficiency of energy utilization of calf-fed Holstein steers.

A dynamic model has been developed to simulate aspects of feedlot lamb growth and body composition, including energy and protein requirements, growth rate, composition of gain, and body mass. Model inputs include initial body mass (kg), standard final mass (kg), age (days), and dietary energy concentration (Mcal·kg−1). The model was assessed as a decision support tool using a dataset of 564 individual measures of final body mass and diet energy. The simulations provide graphical and numerical descriptions of nutrient requirements, composition of gain, and estimates of animal performance over time. The model is accurate and precise, with a root mean squared error of 7.79% of the observed final body mass and a coefficient of determination of 0.89 when simulating the same variable. The model can be used as a reliable decision support tool to estimate final body mass and the days on feed required to reach a certain final mass with precision and accuracy. Moreover, the dynamic model can also serve as a learning tool to illustrate practical principles of animal nutrition, nutrient requirement relationships, and body composition changes. This model holds the potential to enhance livestock management practices and assist producers in making informed decisions about feedlot lamb production.

The objective of the current study was to evaluate the effects of soybean oil inclusion in diets on feeding behaviour, digestibility, performance, and blood metabolites of feedlot lambs. Forty non-castrated Santa Inês lambs with a mean age of 5 months and initial body weight of 34.88 ± 3.19 kg were used in a 40-day feeding trial. The lambs were distributed in five experimental diets with the inclusion of increasing soybean oil (SO) levels: 0, 30, 60, 90, and 120 g/kg DM. The SO inclusion promoted a linear reduction in DM intake (p < 0.001), crude protein (CP, p < 0.001), non-fibrous carbohydrates (NFC, p < 0.001), and total digestible nutrients (TDN, p = 0.004). There was an increasing quadratic effect on the intake of ether extract (EE; p = 0.002) and decreasing for neutral detergent fiber (p = 0.005). The soybean oil inclusion promoted the greater apparent digestibility of CP (p = 0.016), EE (p = 0.005), NDFom (p < 0.001), and TDN (p < 0.001); on the other hand, the apparent digestibility of NFC (p = 0.005) was decreased. The average daily gain decreased (p < 0.001) with SO inclusion. The SO inclusion increased feeding time (p = 0.004), reduced the efficiency of DM rumination (p = 0.001), and reduced the concentration of blood N-ureic (p < 0.001). Considering the productive parameters, SO can be included in diets and it is recommended that we include SO of up to 41 g/kg DM in diets for fattening lambs as the ideal maximum level. The strategy implemented to adapt lambs to increasing levels of high-fat diet mitigated the detrimental effects of lipids on the rumen, with high-density energy intake being the constraining factor on performance.

The aim of this study was to investigate the effects of feeding systems on the growth performance of Santa Inês x Dorper lambs, meat quality, fatty acid profile, and gene expression. Thirty lambs at an initial body weight of 22.6 ± 2.59 kg were randomly assigned to one of three feed systems: a grazing system with 1.2% body weight concentrate supplementation (GS); a feedlot system with 28% forage and 72% concentrate (FFC); or feedlot with 85% whole corn grain and 15% pellets (FHG). The lambs were slaughtered after 60 days of experiment. Average daily gain, glucose, and insulin concentration were higher for lambs on FHC than lambs on a GS feeding system. The fatty acid profile in the meat of the lambs fed GS showed a higher proportion of c9t11-C18:2, C20:5, C22:5, and C22:6 compared with FFC and FHC (p < 0.05). Meat tenderness was lower for lambs under FFC treatment compared with GS and FHG. FHG treatment provides better performance and higher deposition of lipid content in meat compared with GS and FHG. The expression of the genes SCD-1, SREBP1-c, and EVOL6 was greater in lambs undergoing GS and FHC treatments compared with FFC. Results of this research showed a reduced performance of grazing lambs compared with the feedlot system; however, it enhanced the fatty acid profile with increased levels of polyunsaturated acids and reduced n6/n3 ratio.

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 This study aimed to evaluate the performance of reproductive culled lambs kept in confinement, through weight gain, carcass yield, and the state of non-carcass components using two high concentrate diets (90%). One diet was formulated on the property compared to commercially available concentrate. The cost-benefits of each diet were analyzed and compared. We used 24 Corriedale lambs, aged 180 days weighing an average of 28 ± 4 kg. The animals were randomly separated into two groups: the commercial concentrate group (CC) which received 0.4% and 4% of their live weight in Tifton hay and commercial concentrate, respectively, and the property concentrate group (CP) received hay and a high-concentrate diet produced on the property (using whole grain corn as a base), in the same proportions. The study was conducted, for a period of 55 days, along with ten days of adaptation, until they reached 40 ± 2 kg body weight (BW). Animals in the property concentrate group achieved a higher average daily gain (0.232 kg/day), but there was no significant difference in carcass yield between the groups The weights of non-carcass components such as the liver, spleen, and kidneys with fat were higher in the concentrate group. The property concentrate group presented a net income of R$ 0.40, while the animals that received the commercial concentrate presented a negative income of R$ - 0.45, per day. Therefore, the use of a high-grain diet produced on the property under the conditions of this study allowed for better weight gain, and a better cost-benefit ratio.

Objective. The aim of this study was to evaluate the behavior and performance of steers in two different housing areas (10 vs. 100 m2/animal) and two feeding models (daily supply vs. self-feeding) during the fattening period. Materials and methods: Forty-eight Hereford steers with initial live weight (LW): 214,0 kg were housed under four treatments: 100DS (100 m2/animal and daily supply), 100SF (100 m2/animal and self-feeding), 10DS (10 m2/animal and daily supply), 10SF (10 m2/animal and self-feeding) until reaching a final LW of 370 – 390 kg. Behavior was recorded by observation. Dry matter intake (DMI) and average daily gain (ADG) were recorded to estimate feed conversion ratio (FCR). Back fat thickness (BFT) and Longissimus muscle area (LMA) were measured. Steers were sent to a commercial abattoir to evaluate carcass yield. Results: The frequency of rest and walking was higher in steers in the largest housing area. Self-feeding contributed to the intake distribution during the day. No differences were detected in DMI, ADG and FCR. However, the confined animals (10DS and 10SF) produced more BFT and less LMA. In addition, they had less carcass yield at slaughter. Conclusions: Therefore, a larger housing area and the self-feeding model could contribute to express steers’ natural behavior and improve their performance.

The purpose of this study was to determine climatologically suitable places to raise feedlot cattle in Türkiye. The Comprehensive Climate Index (CCI), a model that enables one to quantify beef cattle performance based on environmental conditions (temperature, relative humidity, wind speed, solar radiation) at any time in the year, was used to predict dry matter intake (DMI), average daily gain (ADG), and feed efficiency (FE) of feedlot cattle. Thirty years of daily average temperature, relative humidity, and wind speed values were obtained for 15 cities, namely, Antalya, Balikesir, Çorum, Diyarbakir, Edirne, Elazig, Erzincan, Erzurum, Eskisehir, Isparta, Izmir, Kayseri, Konya, Sivas, and Van. Measured daily solar radiation values were not available and values were calculated based on a formula that takes hemisphere, latitude, and day of the year into account. Since mostly dairy breed calves are placed into a feedlot in Türkiye, the Holstein option in the CCI model was chosen to calculate the maintenance energy requirement. Based on previous feedlot feeding studies conducted in Türkiye, it was assumed that calves would be placed on feed at 250 kg and be marketed at 520 kg, that the diet would have 2600 kcal/kg metabolic energy, and that DMI would be 2.31% of the body weight. Results indicate that cattle raised in Antalya (the hottest place) and Erzurum (the coldest place) had the lowest and highest DMI, respectively (P<0.05). Summer months depressed the DMI of cattle in hotter cities and winter months increased the DMI of cattle in colder cities (P<0.05). Feedlot cattle raised in hotter and colder regions of Türkiye had lower ADG than other places having a more temperate climate (P<0.05). In general, cattle raised in a hotter climate had better FE than those raised in a cold climate (P<0.05). [ABSTRACT FROM AUTHOR]

Simple Summary: In the United States, cattle in feedyards can experience heat stress due to extreme climatic events negatively affecting welfare and productivity. Various heat mitigation strategies have been studied in feedyard settings, but information on the current adoption of those strategies and stakeholder perceptions of strategies and their benefits is limited. This study utilized an online survey to ask feedyard operators, veterinarians, and nutritionists about their perception and use of heat mitigation strategies. Generally, respondents agreed that heat stress impacts cattle performance, health, and welfare. The majority of respondents utilized or recommended some type of heat mitigation such as changing feed delivery time and feed composition, utilizing sprinklers and/or changing processing and handling times. Respondents used a variety of indicators and monitoring tools to aid in identifying when to implement protocols and strategies. Respondents perceived pen infrastructure (i.e., shade, fans) and water/feed management as important considerations for better mitigating the negative effects of heat stress on cattle in the face of another extreme heat event. This survey highlighted the need for future research to evaluate the cost:benefit of different mitigation strategies, the effectiveness of mitigation strategies in different geographical areas, and development of more in-depth heat stress forecasting and monitoring tools. The purpose of this study was to: (1) understand heat mitigation strategies currently used and recommended by feedyard operators, veterinarians, and nutritionists, (2) understand their perceptions of heat mitigation strategies related to cattle health, performance, welfare, and carcass quality, (3) quantify the frequency of extreme heat events, and (4) understand industry needs associated with heat stress mitigation strategies. An online survey was shared via 11 industry association listservs. Descriptive statistics were performed on 56 responses (n = 22 operators, 26 veterinarians and eight nutritionists). Thematic analysis was performed on free-response questions. Sixteen (72.7%) operators, 23 (88.5%) veterinarians and eight (100%) nutritionists utilized at least one heat mitigation strategy. "Changing processing and shipping hours" (n = 42, 75%) had the most "strongly agree" responses when asked about strategy effectiveness. The majority of respondents agreed that heat stress negatively impacts cattle health, performance, and welfare (Mean ± SD; ≥7.8 ± 2.6 for all roles). Forty-two (75%) respondents experienced cattle death loss from extreme heat events. Thematic analysis indicated that respondents perceived pen infrastructure and water/feed management as important considerations for better mitigating heat stress impacts. When asked what resources would be helpful, respondents indicated research and data regarding the effectiveness of various strategies. [ABSTRACT FROM AUTHOR]