Drylot Pens Research Articles

Breed and trace mineral source influence the performance of beef heifers during periods of nutrient restriction and grazing forage at early vegetative stage.

We evaluated the effects of breed and mineral source on heifer performance during periods of nutrient restriction and grazing. On day -7, ½ Angus × ½ Nelore (ANE) and Nelore (NE) heifers (12 heifers per breed; body weight, BW = 264 ± 35kg; age = 15 ± 1 mo) were assigned to individual drylot pens to receive ad libitum Tifton 85 (Cynodon sp.) hay and white salt for 7 days. On day 0, within each breed, heifers were randomly assigned (2 × 2 factorial arrangement) to receive protein supplementation (0.20% of BW; dry matter, DM) added with sulfate (SUL) or hydroxychloride (HYD) sources of Cu, Mn, and Zn from day 0 to 49. From day 0 to 34, hay DM intake was restricted to 50% of the ad libitum intake recorded from day -7 to -1. On day 35, heifers were transferred to individual pastures to graze Tifton 85 forage at early vegetative stage until day 49. No effects of breed × mineral source × day and breed × mineral source were detected (P ≥ 0.11). Nelore heifers had greater (P ≤ 0.02) average daily gain (ADG) from day 0 to 35 and day 0 to 49 compared to ANE heifers. Cumulative diarrhea incidence, fecal pH and total days of diarrhea symptoms did not differ (P ≥ 0.19) between breeds. Nelore heifers had greater (P ≤ 0.05) serum concentrations of insulin-like growth factor 1 (IGF-1) from day 35 to 45 but had less (P ≤ 0.05) serum concentrations of cortisol and haptoglobin on day 42 and 45, respectively. Serum concentrations of urea N were greater (P ≤ 0.05) for NE vs. ANE heifers on days 0 and 42 and were less (P ≤ 0.05) for NE vs. ANE on days 38, 45 and 49. Heifers supplemented with HYD had (P ≤ 0.05) greater ADG from day 0 to 35, lower cumulative diarrhea incidence and percentage of heifers exhibiting ≥ 2 days of diarrhea from day 36 to 49, less serum concentrations of non-esterified fatty acids (NEFA) on day 35, and less serum concentrations of NEFA, cortisol and urea N on day 38 compared to SUL heifers. In summary, breed influenced serum concentrations of haptoglobin, cortisol, urea N, insulin and IGF-1, and the growth of beef heifers during nutrient restriction, but did not impact growth and incidence of diarrhea during periods of grazing forage at early vegetative stage. Regardless of breed, replacing sulfate with hydroxychloride sources of Cu, Mn, and Zn led to minimal reductions on serum concentrations of NEFA, cortisol and urea N, enhanced growth during nutrient restriction, and reduced diarrhea incidence during grazing of early vegetative forage.

326 Relationship between activity and social interactions of beef bulls during the pre-breeding period and siring capacity in multi-sire breeding groups

Abstract It is currently unknown whether the behavior of bulls during pre-breeding is related to their siring capacity. This information could help producers anticipate the reproductive potential of their bulls and include it in their decision-making. This study aimed to investigate the relationship between the activity and characteristics of social interaction of beef bulls expressed in drylot pens during the pre-breeding period and their siring capacity. Collars with 3-axis accelerometers and proximity sensors were placed on bulls for 12 d prior to breeding season in 2020 (n = 11 bulls) and in 2021 (n = 10 bulls). Bulls were satisfactory at the breeding soundness evaluation, and ages ranged from 1.5 to 5.4 yr. Afterward, bulls were exposed to cows in multi-sire groups at a 1:30 ratio for 2 mo, however, some bulls were removed early due to injuries (range = 15 to 62 d). DNA samples were collected from bulls and calves to calculate the number of calves sired per bull (SRC), adjusted to days exposed to cows. Daily proportion of time active (AC) was measured through a machine learning algorithm created in Python for beef bulls to differentiate activity vs. non-activity from accelerometer data every 20 sec (Precision = 95%). Daily non-directional social networks were created from proximity perceived by the sensors (Precision = 91%, <3m) in Python, where nodes represented bulls and a connection represented one second in proximity. Eigencentrality (how well connected a bull is to others, EC) and strength (proportion of connections among overall connections, ST) were calculated for each bull daily, where greater EC and ST values indicated more interactions. The statistical analyses were performed in RStudio. Negative binomial mixed effect models were fitted to AC (mean ± S.E., 26.05 ± 0.31 %), EC (26.50 ± 0.89), and ST (8.90 ± 0.21 %) as repeated measures, age (3.3 ± 0.3 yr), days exposed to cows (54 ± 3.1 d), and year as covariates, identification of bull as a random effect, and SRC as the outcome variable (21 ± 2, 2 to 45 calves). Estimates were transformed into percentage change. Days exposed to cows, year, and interactions were not significant (P > 0.05). Separate models with EC or ST (model-EC and model-ST) were built due to collinearity (r = 0.89, P < 0.001). In model-EC (marginal-R2 = 0.26, conditional-R2 = 0.70) bulls with increased AC (estimate = 2.16±0.67, P = 0.001), increased EC (0.56±0.24, P = 0.019), and younger (-20.75 ± 5.51, P < 0.001) had greater SRC. In model-ST (marginal-R2 = 0.25, conditional-R2 = 0.72) bulls with increased AC (2.29 ± 0.65, P < 0.001), increased ST (3.57 ± 0.98, P < 0.001), and younger (-19.90 ± 5.49, P < 0.001) had greater SRC. These preliminary results suggest that activity and social interactions during pre-breeding of beef bulls are related to SRC when accounted for age. Therefore, the behavior of beef bulls during the pre-breeding period might have the potential to predict their SRC, and future studies could investigate using this information to select bulls and form breeding groups aiming at optimization of the use of the bulls.

127 Effects of maternal pre- and post-partum supplementation of a Bacillus-based DFM on plasma metabolome profile of Bos indicus-influenced heifers and their offspring

Abstract This study evaluated the effects of maternal supplementation during pre- and postpartum of a Bacillus-based direct-fed microbial (DFM) on plasma metabolome of Bos indicus-influenced cow-calf pairs. On d 0, 72 pregnant Brangus crossbred beef heifers (20 to 22 mo of age) were stratified by their initial body weight (BW; 431 ± 31 kg) and body condition score (BCS; 6.0 ± 0.36), and randomly allocated into 1 of 12 bahiagrass pastures (1 ha and 6 heifers/pasture). Treatments were randomly assigned to pastures (6 pastures/treatment) and consisted of heifers supplemented with 1 kg/d of soybean hulls dry matter added (BAC) or not (CON) with a Bacillus-based DFM mixture (Bovacillus; Chr. Hansen A/S, Hørsholm, Denmark) from d 0 to 242 (139 ± 4 d prepartum to 104 ± 4 d postpartum). Calves were weaned on d 242 (96 ± 30 d of age) and then allocated into 1 of 12 drylot pens and limit-fed the same concentrate at 3.25% of BW until day 319. On d 271 and 287, calves were vaccinated against pathogens associated with bovine respiratory disease and Clostridium. Blood samples were collected from all heifers on d 0 and 63 and from all calves on d 271, 274, and 287 to determine the plasma concentration of metabolites using liquid chromatography. The PLS-DA revealed a clear separation of plasma metabolome profile of BAC and CON heifers and offspring. For the heifer metabolome, 66.5% of the treatment separation on d 63 was explained using 3 components (R2 = 0.96), and BAC heifers had increased (P ≤ 0.05) plasma concentration of 17 metabolites, including phosphatidylcholines and amino acids related classes, but decreased (P ≤ 0.05) plasma concentration of 4 metabolites from triglycerides class compared with CON heifers. For the calf metabolome, 45.6 (R2 = 0.95), 56.7 (R2 = 0.95), and 61.3% (R2 = 0.99) of the treatment separation on d 271, 274, and 287, respectively, were explained using 3 components. Plasma concentrations of 9, 10, and 28 metabolites associated with protein and fatty acid metabolism increased (P ≤ 0.05) in BAC vs. CON calves on d 271, 274, and 287, respectively. Compared with CON, BAC calves had increased (P ≤ 0.05) concentration of metabolites from phosphatidylcholines class all days, from amino acids related class on d 274 and 287, and from triglycerides class on d 287. Plasma concentrations of 3 and 6 metabolites from triglycerides class decreased (P ≤ 0.05) in BAC vs. CON calves on d 271 and 274, respectively. Thus, maternal supplementation of Bacillus-based DFM altered the plasma metabolome of heifers and their calves, leading to increased plasma concentrations of phosphatidylcholine and amino acids related classes in heifers and calves, but fluctuating effects on triglycerides class concentrations in calves.

18 Impacts of supplementing sulfate vs. hydroxychloride sources of Cu, Mn, and Zn on heifer growth performance and physiology during feed restriction and high-starch challenge periods

Abstract This study evaluated the effects of supplementing different sources (sulfate vs. hydroxychloride) of Cu, Mn, and Zn during feed restriction and high-starch challenge periods on heifer growth performance and physiology. On d 0, Nelore heifers (n = 40) were stratified by body weight (BW = 238 ± 38 kg) and age (21 ± 1 mo), and individually allocated into 1 of 40 drylot pens. The study was divided: washout (d 0 to 27), nutrient surplus (d 28 to 55), nutrient restriction (d 56 to 83), and high-starch challenge (d 84 to 112). The washout period consisted of limit-feeding Tifton hay (2.5% of BW; DM basis) and providing free choice access to white salt only. On d 28, heifers were randomly assigned to receive protein DM supplementation (0.10 to 0.20% of BW) added with sulfate (SUL) or hydroxychloride (HYD) sources of Cu, Mn, and Zn (≥ 260, 200, and 960 mg of Cu, Mn, and Zn per kg of supplement DM) from d 28 to 112 (n = 20 heifers/treatment). From d 28 to 55, heifers were offered ad libitum Tifton hay. From d 56 to 83, heifers were limit-fed 50% of average hay DM intake consumed in the last 6 d of the previous phase (d 50 to 55). From d 84 to 112, each respective protein supplement was mixed with a starch-based total mixed ration (TMR). Heifers were gradually adapted to the starch-based TMR by increasing the concentrate DM amount while simultaneously decreasing the hay DM amount by 20% every 7 d (starting with 35% concentrate and 65% hay on d 84 and ending with 80% concentrate and 20% hay from day 106 to 112). Individual heifer shrunk BW were collected on d 0, 28, 56, 84, and 112, following 12 h of feed and water withdrawal. Effects of treatment × day and treatment were not detected (P ≥ 0.37) for heifer BW, average daily gain (ADG), and dry matter (DM) intake, except for ADG from d 28 to 56, which was less (P = 0.05) for SUL vs. HYD heifers (-0.21 ± 0.05 vs. -0.10 ± 0.05 kg/day, respectively). Effects of day, but not treatment × day and treatment (P ≥ 0.43), were detected for fecal pH, which remained relatively constant from d 0 to 84, and then decreased (P < 0.01) from 7.2 on d 84 to 5.8-6.0 on d 110. Overall, protein supplementation added with hydroxychloride sources of Cu, Mn, and Zn had minor positive effects on heifer growth performance immediately following a washout period, but did not improve heifer growth performance and fecal pH during nutrient restriction and high-starch challenge periods, compared with protein supplementation added with sulfate sources of same metals.

Assessing supplementing strategies for beef cattle in a bale grazing system using grass hay during variable winter conditions

IntroductionBeef cattle in the Northern Great Plains of the United States of America are normally kept in open dry lot pens in winter. Practices such as bale grazing, swath grazing, stockpiling, and corn residue grazing, can be used to extend the grazing season and minimize dry lot use. Extending the grazing season has several advantages over dry lot use but arguably the most important benefit is cost savings due to lower labor and input costs. Strategies selected to supplement cattle in extended grazing systems should maintain cost savings while providing required nutrients to cattle. This study was conducted to evaluate supplementing strategies for beef cattle in a bale grazing system using grass hay during variable winter conditions. The study was conducted across variable winter conditions that are encountered in winters in the US Northern Great Plains.MethodsThe study extended over four years. Each year, non-lactating pregnant beef cows (n = 64, year 1; n = 80, year 2, 3, 4) were divided into eight groups of similar average body weight and randomly assigned to one of four bale grazing treatments as follows: a) bale grazing grass hay, b) bale grazing grass hay treated with a liquid supplement, c) bale grazing grass hay and alfalfa hay, and d) bale grazing grass hay and plus 1.8 kg corn DDGS/head/day. Animal performance was assessed from two-day body weights and body condition scores taken at the start and end of the study. Data analysis considered the fixed effects of treatment, year, and treatment x year interaction.ResultsFinal BW tended (P = 0.09) to be greatest following corn DDGS supplementation and lowest when grass hay was offered. The treatment strategy x year interaction (P = 0.026) for ADG showed that corn DDGS supplementation resulted in positive ADG across the years regardless of environmental conditions. Liquid or alfalfa hay supplementation resulted in positive ADG when environmental conditions were favorable. Final BCS (P = 0.005) and BCS change (P = 0.004) were greater following corn DDGS supplementation, intermediate following alfalfa hay or liquid supplementation and lowest when grass hay was fed. Supplementation costs ranged from $1.33 to $1.90/head/day, the highest cost occurred with corn DDGS supplementation mainly due to cost of corn DDGS and labor required to deliver corn DDGS to cattle on pasture.DiscussionAlfalfa hay or molasses-based liquids increased diet CP content but did not supply adequate energy in severely cold winters. Despite relatively higher supplement costs, high energy supplements such as corn DDGS may be required in severely cold winters where cattle require extra energy. Supplement selection should consider supplement effectiveness to meet animal nutrient requirements particularly in adverse winter conditions such as those encountered in the US Northern Great Plains.

Plasma proteomic analysis reveals key pathways associated with divergent residual body weight gain phenotype in beef steers.

We utilized plasma proteomics profiling to explore metabolic pathways and key proteins associated with divergent residual body weight gain (RADG) phenotype in crossbred (Angus × Hereford) beef steers. A group of 108 crossbred growing beef steers (average BW = 282.87 ± 30 kg; age = 253 ± 28 days) were fed a high-forage total mixed ration for 49 days in five dry lot pens (20-22 beef steers per pen), each equipped with two GrowSafe8000 intake nodes to determine their RADG phenotype. After RADG identification, blood samples were collected from the beef steers with the highest RADG (most efficient; n = 15; 0.76 kg/d) and lowest RADG (least efficient; n = 15; -0.65 kg/d). Plasma proteomics analysis was conducted on all plasma samples using a nano LC-MS/MS platform. Proteins with FC ≥ 1.2 and false-discovery rate-adjusted p-values (FDR) ≤ 0.05 were considered significantly differentially abundant. The analysis identified 435 proteins, with 59 differentially abundant proteins (DAPs) between positive and negative-RADG beef steers. Plasma abundance of 38 proteins, such as macrophage stimulating 1 and peptidase D was upregulated (FC ≥ 1.2, FDR ≤ 0.05) in positive-RADG beef steers, while 21 proteins, including fibronectin and ALB protein were greater (FC < 1.2, FDR ≤ 0.05) in negative-RADG beef steers. The results of the Gene Ontology (GO) analysis of all the DAPs showed enrichment of pathways such as metabolic processes, biological regulation, and catalytic activity in positive-RADG beef steers. Results of the EuKaryotic Orthologous Groups (KOG) analysis revealed increased abundance of DAPs involved in energy production and conversion, amino acid transport and metabolism, and lipid transport and metabolism in positive-RADG beef steers. The results of this study revealed key metabolic pathways and proteins associated with divergent RADG phenotype in beef cattle which give more insight into the biological basis of feed efficiency in crossbred beef cattle.

PSV-13 The influence of diet type on beef cattle performance and meat quality characteristics

Abstract The objective of this study was to determine what additive effect hormonal implants and inclusion of beta-agonists in the diet have on carcass quality in yearling beef steers. Hereford-cross steers [n = 21; initial body weight (BW) = 450 ± 15 kg] were assigned to one of three drylot pens based on initial BW and sire so that each pen had an equal starting BW and sires were equally represented in each pen. Each drylot pen was assigned to one of three treatments: receiving a hormonal implant (IMP), consuming a beta-agonist (BAG), or receiving both of the previous treatments (AND). All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement [22.0% CP, 2.90 Mcal ME/kg dry matter (DM)]. Animals were fed daily at 0700 and 1700 h and weighed weekly at 0630 h. For the duration of the trial, animals were housed in drylot pens with ad libitum access to feed and water and had shade structures in each pen. Following a 15-d adaptation period, feed intake was recorded for 45 d. Body weight gain for each treatment group were 1.26, 1.28, and 1.48 kg/d for IMP, BAG, and AND, respectively. Animals on the AND treatment were significantly more feed efficient than the IMP treatment with F:G ratios of 5.9 kg/kg gain and 6.8 kg/kg gain, respectively. After the intake portion of the study was completed, an animal from each pen was slaughtered and evaluated for carcass quality. Hot carcass weights for diets IMP, BAG, and AND were 347.4, 352.9, and 394.8 kg, respectively. Data were analyzed as a completely random design in SAS v9.4. There was not a significant difference between the IMP treatment and the AND treatment based on assessment from Warner-Bratzler shear force, carcass yield, marbling score, and sensory assessment (P &amp;gt; 0.05); however, the BAG treatment had less marbling than the other two treatments. It was concluded that the additive effect of using both a hormonal implant and a beta-agonist can improve feed intake and feedlot performance without detrimental effects on carcass quality.

PSV-6 The additive effect of hormonal implant and inclusion of beta-agonists in carcass quality in beef cattle

Abstract The objective of this study was to determine what additive effect hormonal implants and inclusion of beta-agonists in the diet have on carcass quality in yearling beef steers. Twenty-one Hereford-cross steers (450 ± 15 kg) were assigned to one of three drylot pens based on initial body weight (BW) and sire so that each pen had an equal starting BW and sires were equally represented in each pen. Each drylot pen was assigned to one of three treatments: receiving a hormonal implant (IMP), consuming a beta-agonist (BAG), or receiving both of the previous treatments (AND). All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement (22.0% CP, 2.90 Mcal ME/kg DM). Animals were fed daily at 0700 and 1700 and weighed weekly at 0630. For the duration of the trial, animals were housed in drylot pens with ad libitum access to feed and water and had shade structures in each pen. Following a 15-d adaptation period, feed intake was recorded for 45 d. Weight gain for each treatment group were 1.26, 1.28, and 1.48 kg/d for IMP, BAG, and AND, respectively. After the intake portion of the study was completed, an animal from each pen was slaughtered and evaluated for carcass quality. Hot carcass weights for diets IMP, BAG, and AND were 347.4, 352.9, and 394.8 kg, respectively. Following 14 d aging, samples from the ribeye area were collected from each animal and subjected to sensory analysis and other assessments of quality. Data were analyzed as a completely random design in SAS v9.4. There was not a significant difference between the IMP treatment and the AND treatment based on assessment from Warner-Bratzler shear force, carcass yield, marbling score, and sensory assessment (P &amp;lt; 0.05); however, the BAG treatment had significantly less marbling than the other two treatments. It was concluded that the additive effect of using both a hormonal implant and a beta-agonist can produce carcass of good quality without detrimental effects on meat quality when compared with a beta-agonist only inclusion.

89 Evaluation of repeatability of anogenital distance measured with either a caliper or photogrammetry

Abstract The objective was to determine the repeatability of anogenital distance (AGD) measurements over time in growing heifers and evaluate the relationship of photogrammetric and caliper AGD measurements. Reproductive success is one of the most important determinants of profitability in the beef industry. However, fertility traits generally have low heritability, and there are few phenotypic traits that correlate to fertility in beef cattle. The AGD is the distance from the center of the rectum to the base of the clitoris. Recently, researchers in dairy cattle have reported a correlation between shorter AGD and improved fertility. In the published dairy research, AGD has been measured with the use of calipers. Photogrammetric measurement could be a quicker and safer way of taking the measurement and easier to implement on farm. Heifers (n = 153), either Angus or Hereford sired by commercial dams, were used in the analysis. Heifers were early weaned at 82 ± 7 d of age. Following weaning, heifers were managed in partially covered, dry lot pens and fed a moderate roughage growing diet. The heifers rotationally grazed predominantly tall fescue pastures beginning in April of 2023. Heifer AGD was evaluated monthly from June to September. Heifers weighed 210 ± 22 kg and 282 ± 6 d of age at the time of the first AGD measurements. Heifer body weight was collected monthly at time of AGD measurements. The heifers were restrained in a squeeze chute and had their tail held in a relaxed upright position and AGD was measured with a caliper. Immediately following caliper measurements, anogenital photographs were taken with an Iphone 14 plus. A white board with a forensic photomacrographic scale attached and the ear tag number recorded on the right corner was held adjacent to the vulva and was included in the photograph. Photographs were converted from HEIC to JPEG. A software program, Digitizer, was used to set the measurement scale using the forensic photomacrographic scale. The AGD was then digitally measured from the center of the rectum to the base of the clitoris. Repeatability of AGD and relationship of caliper and photogrammetric AGD were evaluated using the CORR procedure of SAS 9.4. Caliper AGD measurements were repeatable as all of the time points were moderately correlated (r ≥ 0.47; P ≤ 0.01) throughout the evaluation period. Photogrammetric AGD measurements were also repeatable as all of the time points were correlated (r ≥ 0.21; P ≤ 0.02) throughout the evaluation period. Photogrammetric AGD had a moderate correlation (r ≥ 0.44; P ≤ 0.01) with the caliper AGD measurements. In conclusion, AGD measurements were repeatable in growing heifers regardless of measurement method. Photogrammetric measurements may be a viable option for estimating AGD as they were strongly correlated to caliper measurements of AGD.

PSV-1 A comparison of Holstein-cross cattle and beef-cross cattle in terms of performance and carcass quality

Abstract Crossbreeding Holstein cows to beef sires has increased in popularity as a means to increase marketability of the dairy offspring. A large portion of these dairy-cross animals are offspring of Holstein cows and Angus bulls. The objective of this study was to evaluate the carcass quality of 3 crossbred beef steers (Hereford x Angus) and 3 dairy x beef cross steers (Holstein x Angus). These animals had been a part of a previous study evaluating the additive effect of implanting strategy combined with inclusion of a beta-agonist and represent the three different treatments evaluated on that study with one dairy-cross and one beef-cross animal coming from each treatment. All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement (22.0% CP, 2.90 Mcal ME/kg DM). Animals were fed daily at 0700 and 1700 and weighed weekly at 0630. For the duration of the trial, animals were housed in drylot pens with ad libitum access to feed and water and had shade structures in each pen. Following a 15-d adaptation period, feed intake was recorded for 45 d. Data were analyzed as a completely random design in SAS v9.4. The animals were evaluated in terms of growth and performance, carcass quality, and feed efficiency. There was no difference in intake for either treatment; however, beef-cross steers gained significantly more than their dairy-cross counterpart on the same diet. After the intake portion of the study was completed, all six chosen animals were slaughtered and evaluated for carcass quality. Following 14 d aging, samples from the ribeye area were collected from each animal and subjected to sensory analysis and other assessments of quality. Other than a numerical difference in marbling score between treatments, there were no statistical differences in meat quality between the two crosses indicating that dairy-cross animals are an important addition to the beef industry.

PSVI-2 Economic evaluation of forage-fed vs concentrate-fed beef finishing systems

Abstract The objective of this study was to determine the economic benefit of implanting beef steers and including a beta-agonist in the finishing diet. To accomplish this, Hereford-cross steers (450 ± 15 kg) were assigned to one of three drylot pens based on initial body weight (BW) and sire so that each pen had an equal starting BW and sires were equally represented in each pen. Each drylot pen was assigned to one of three treatments: receiving a hormonal implant (IMP), consuming a beta-agonist (BAG), or receiving both of the previous treatments (AND). All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement [22.0% CP, 2.90 Mcal ME/kg dry matter (DM)]. The data were analyzed in SAS v9.4. Animals were evaluated on intake, growth, and performance measures during a 45-d feeding trial. Average daily gain (ADG) and hot carcass weight differed (P &amp;lt; 0.05) between treatments with AND steers gaining 1.48 kg/d with a hot carcass weight of 394.8 kg, BAG steers gaining 1.28 kg/d with a hot carcass weight of 352.9 kg, and IMP steers gaining 1.26 kg/d with a hot carcass weight of 347.4 kg. The BAG treatment rendered decreased marbling scores than IMP and AND (P &amp;lt; 0.05). It was concluded based on carcass quality data that there was no difference in the IMP and AND treatments, though the AND treatment had greater growth rates and feed conversion rates. Results of this trial are expected to indicate at what price point it becomes economically effective to finish animals using a beta-agonist in conjunction with a hormonal implant.

101 Effects of moderate exercise regimen on reproductive development of replacement beef heifers reared in drylots at a high stocking density

Abstract This experiment evaluated growth and reproductive development of beef heifers reared at a high stocking density and provided with access to an exercise area. The experiment was replicated over 2 yr, with a total of 180 Angus × Brahman heifers. Each year, 90 heifers were ranked by age (264 ± 1 d) and body weight (BW; 200 ± 2 kg) on d 0, and assigned to a) 1 of 6 drylot pens (10 × 14 m pens; 10 heifers/pen) resulting in a stocking density of 14 m2/heifer (DENS), or b) 1 of 3 paddocks (2-ha paddocks; 10 heifers/paddock) resulting in a stocking density of 2,000 m2/heifer (CON). On d 15, 3 DENS pens were randomly selected and given access to an exercise area (DENS-EX) for 1 h three times weekly. Negligible forage was available for CON heifers, whereas all heifers received the same limit fed diet which averaged 13 kg/heifer daily of a corn-based diet. Heifer shrunk BW was recorded after 16 h of feed and water withdrawal on d -3 and 225 for BW gain calculation. Heifer temperament (chute score, exit velocity, and temperament score) were evaluated on d 0 and 225. Heifers were also fitted on d 0 with a pedometer behind their shoulder and an ear tag (CowManager, Select Sires, Plain City, OH) to record behavioral responses. Each week, pedometer results were recorded, and blood samples were collected for puberty evaluation via plasma progesterone. Heifers from CON had more (P &amp;lt; 0.05) steps per week compared with DENS and DENS-EX (23,973, 6,706, and 12,354 steps/week, respectively; SEM = 1,247), and DENS-EX heifers had more (P &amp;lt; 0.05) steps per week compared with DENS. Heifers from CON spent more (P &amp;lt; 0.05) time ruminating and eating compared with DENS and DENS-EX. No treatment effects (P ≥ 0.91) were detected for heifer BW gain (0.820, 0.815, and 0.824 kg/d for CON, DENS, and DENS-EX, respectively; SEM = 0.016). Heifers from DENS had greater (P ≤ 0.05) exit velocity and temperament score on d 225 compared with DENS-EX and CON. Heifers from DENS experienced delayed puberty attainment (treatment x day; P &amp;lt; 0.01) compared with DENS-EX and CON. A greater (P ≤ 0.05) proportion of CON heifers were pubertal by day 105 compared with DENS and DENS-EX (30.0, 11.6, and 15.0%, respectively; SEM = 6.5), whereas a greater (P &amp;lt; 0.05) proportion of CON and DENS-EX heifers were pubertal by d 154 compared with DENS (61.7, 66.7, and 43.3%, respectively; SEM = 6.5). Results from this experiment demonstrate that providing heifers with an exercise area alleviated the negative effects associated with high stocking density on their reproductive development. This work is supported by the USDA-NIFA AFRI program (#2021-67015-34083).

150 Effects of diet type on performance and methane yield in replacement beef heifers

Abstract The objective of this experiment was to determine the relationships among enteric gas production, body weight (BW) gain, and feed intake for growing heifers consuming two energy divergent diets. Fifty-five fall born yearling Angus and Angus cross heifers were used in a 157-d experiment. Heifers were fed two consecutive diets at the Oklahoma State University Range Cow Research Center. Heifers were sorted into one of two drylot pens based on BW. Each drylot pen was equipped with individual intake monitoring system (C-Lock Inc., Rapid City, SD) with a stocking rate of 3.3 heifers per feeder. The first intake segment (HAY) was initiated with a 21 d of adaptation followed by 70 d of data collection. Heifers were offered ad libitum access to long stem unprocessed bermudagrass hay and a salt/mineral/vitamin supplement. After the HAY period, heifers were adapted to a 50% forage, 50% concentrate diet (TMR) during a 14-d adaptation period, followed by 52-d of data collection. Means and standard deviations for phenotypic traits of DMI, ADG, RFI, and CH4 were 6.7 ± 0.7 kg, 0.44 ± 0.13kg, and 194.6 ± 17.56 g/d respectively for HAY and 14.3 ± 1.34 kg, 1.72 ± 0.20 kg, and 280 ± 24.69 g/d respectively for TMR. Pearson correlations between diets for DMI, ADG, and CH4 were 0.32, -0.16, and 0.29, respectively. Coefficient of variation for DMI was 10.8% for HAY and 9.4% for TMR. Coefficient of variation for ADG was 29.9% for HAY and 11.6% for TMR. Methane intensity was calculated as CH4, g/day divided by DMI, kg/d resulting in 29.6 ± 3.5 and 19.9 ± 2.2 g CH4/kg DMI for HAY and TMR, respectively. In summary, HAY DMI was moderately and positively correlated with TMR DMI while ADG was not correlated among the two diet types. The HAY diet generated less total daily CH4, although more CH4 per unit of feed intake.

88 Impacts of trace mineral source and ancillary drench on steer performance during a 60-day backgrounding phase

Abstract This experiment evaluated the impacts of supplementing organic complexed Cu, Co, Mn, and Zn on productive and health responses of high-risk beef cattle during a 60-d backgrounding phase. Crossbred steers (n = 120) were purchased at auction and transported to the experimental facility. Steer BW was recorded at arrival (d -1; initial shrunk BW = 227.7 ± 1.3 kg). On d 0, steers were ranked by BW and allocated to 1 of 8 groups (8 steers/group) and housed in drylot pens (6 m x 12 m) equipped with GrowSafe automated feeding systems (Model 8000; 2 bunks/pen; d 0 to 60). Groups were randomly assigned to receive a total mixed ration (TMR; 47% corn) containing: 1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 40); 2) organic complexed sources of Cu, Mn, Co, and Zn (AAC; Zinpro Availa 4; Zinpro Corp., Eden Prairie, MN; n = 40); or 3) AAC and an organic complexed trace mineral drench (APF; 30 mL/hd; Zinpro ProFusion, Zinpro Corp.) on d 0 and ancillary to morbidity treatment (n = 40). Diets provided the same daily amount of energy, protein, macro minerals and trace minerals based on 7 g/steer daily of Zinpro Availa 4. Steers were assessed for bovine respiratory disease (BRD) signs daily. Liver biopsies were performed on day 0, 28 and 60. Final BW was recorded on d 60 and 61. Blood samples were collected on d 0, 2, 6, 10, 13, 21, 28 and 45. No treatment differences were detected (P ≥ 0.23) for TMR intake, final BW, ADG, feed efficiency, or BRD incidence. Mean liver Co concentrations were greater (P = 0.02) in AAC and APF compared with INR steers. Mean liver Cu was greater (P = 0.02) in APF compared with AAC steers. Liver Zn tended to be greater (P = 0.10) on d 28 but less (P = 0.05) on d 60 for INR compared with AAC and APF steers. Plasma cortisol was least (P = 0.05) for steers supplemented with AAC on d 6, whereas AAC steers tended to have greater (P = 0.09) plasma cortisol on d 13 compared with APF. Plasma haptoglobin tended to be greater (P ≤ 0.10) for INR steers on d 28 and 45 compared with AAC and APF. While supplementing cattle with AAC or INR results in similar animal performance and clinical disease, AAC and APF reduces stress and acute phase protein responses.

104 Maternal pre- and post-partum supplementation of Bacillus-based DFM enhanced cow and calf performance

Abstract This study evaluated the effects of maternal supplementation of Bacillus-based direct-fed microbials (DFM) on physiology and growth performance of Bos indicus-influenced cow-calf pairs. On d 0 (~139 d before expected calving date), 72 fall-calving, Brangus crossbred beef heifers (25 to 37.5% Bos indicus; 20 to 22 mo of age) pregnant with their first offspring were stratified by their initial body weight (BW; 431 ± 31 kg) and body condition score (BCS; 6.0 ± 0.36; scale 1 to 9), and randomly allocated into 1 of 12 bahiagrass pastures (1 ha and 6 heifers per pasture). Treatments were randomly assigned to pastures (6 pastures per treatment) and consisted of heifers supplemented with 1 kg/d of soybean hulls dry matter (DM) added (BAC) or not (CON) with a Bacillus-based DFM mixture (BovacillusTM; Chr. Hansen A/S, Hørsholm, Denmark) from d 0 to 242 (139 ± 4 d prepartum to 104 ± 4 d postpartum). Calves were weaned on d 242 (96 ± 30 d of age) and then allocated into 1 of 16 drylot pens and limit-fed the same concentrate at 3.25% of BW until d 319. Maternal treatment effects were not detected (P ≥ 0.29) for herbage allowance, forage nutritive value, and heifer activity on pasture. Heifer BCS on d 39 and 63 tended (P ≤ 0.09) to be greater, whereas heifer BCS on d 91 was greater (P = 0.01) for BAC vs. CON heifers and did not differ (P ≥ 0.20) between treatments on d 179 and 242. Plasma concentrations of glucose did not differ from d 0 to 63 (P ≥ 0.14) but were greater (P = 0.005) on d 179 and tended (P = 0.09) to be greater on d 242 for BAC vs. CON heifers. First offspring BW at birth, ADG from birth to early weaning, and BW weaning did not differ (P ≥ 0.19), but BW at drylot exit (d 319) was greater (P = 0.05) for BAC vs. CON calves. Maternal treatment effects were not detected (P ≥ 0.42) for calf serum concentrations of IgG at birth, and post-vaccination plasma concentrations of glucose, cortisol and haptoglobin. However, serum titers against bovine respiratory syncytial virus (BRSV) were greater (P = 0.04) for BAC vs. CON calves on d 287, whereas seroconversion against parainfluenza 3 virus (PI-3) was greater (P &amp;lt; 0.01) for BAC vs. CON calves on d 271. Thus, maternal supplementation of Bacillus-based DFM increased prepartum BCS gain and postpartum plasma concentrations of glucose of heifers and led to positive carryover effects on post-weaning BW gain and some indicators of humoral immune response to vaccination in their first offspring.

Impacts of trace mineral source and ancillary drench on steer performance during a 60-day backgrounding phase

Nutritional approaches to optimize cattle health and performance during the receiving period are warranted. This experiment evaluated the impacts of supplementing organic complexed Cu, Co, Mn, and Zn on productive and health responses of high-risk beef cattle during a 60-day backgrounding phase. Crossbred steers (120) were purchased at auction and transported to the experimental facility, where BW was recorded (day−1; initial shrunk BW = 227.7 ± 1.3 kg). On day 0, steers were ranked by BW and allocated to one of eight groups and housed in drylot pens equipped with GrowSafe automated feeding systems (Model 8000; two bunks/pen). Groups were randomly assigned to receive a total mixed ration containing: (1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 40); (2) organic complexed sources of the same minerals (AAC; Zinpro Availa 4 based on a metal:amino acid complex ratio of 1:1 for Zn, Cu, and Mn in addition to cobalt glucoheptonate; Zinpro Corp., Eden Prairie, MN; n = 40); or (3) AAC and an organic complexed trace mineral drench (APF; 30 mL/hd; Zinpro ProFusion, Zinpro Corp.) on day 0 and with morbidity treatment (n = 40). Diets provided the same daily amount of all nutrients and minerals based on 7 g/steer daily of Zinpro Availa 4. Steers were assessed for bovine respiratory disease (BRD) signs daily. Liver biopsies were performed on days 0, 28 and 60. Blood samples were collected on days 0, 2, 6, 10, 13, 21, 28 and 45. No treatment differences were detected (P ≥ 0.23) for feed intake, final BW, average daily gain, or BRD incidence. Mean liver Co concentrations were greater (P = 0.02) in AAC and APF compared to INR steers. Mean liver Cu was greater (P = 0.02) in APF compared to AAC steers. Liver Zn tended to be greater (P = 0.10) on day 28 but less (P = 0.05) on day 60 for INR compared to AAC and APF steers. Plasma cortisol was lowest (P = 0.05) for AAC steers on day 6, whereas AAC steers tended to have greater (P = 0.09) plasma cortisol on day 13 compared with APF. Plasma haptoglobin tended to be greater (P ≤ 0.10) for INR steers on days 28 and 45 compared to AAC and APF. While supplementing cattle with AAC or INR results in similar animal performance and clinical disease, AAC and APF reduce stress and acute phase protein responses.

Effects of amoderate exercise regimen on development and puberty attainment of beef heifers reared in drylots at a high stocking density.

This experiment evaluated growth, physiological responses, and puberty attainment in beef heifers reared in drylots with a high stocking density, and provided or not with a moderate exercise regimen. A total of 180 heifers (75% Angus × 25% Brahman) were used in this experiment replicated over 2 yr. Each year, 90 heifers were ranked by age (264 ± 1 d) and body weight (BW on day -3; 200 ± 2kg) on day 0, and assigned to a) one of six drylot pens (10 × 14 m pens; 10 heifers per pen) with a stocking density of 14 m2/heifer (DENS), or b) one of three pastures (2-ha pastures; 10 heifers per pasture) with a stocking density of 2,000 m2/heifer (CON). Beginning on day 15, three DENS pens were given access to an exercise area (DENS-EX) 3 times/wk (1h). Negligible forage was available for CON, whereas heifers from all treatments received the same limit-fed diet (~13kg/heifer daily). Shrunk BW was recorded after 16h of feed and water withdrawal on days -3 and 225 to calculate BW gain. Temperament was evaluated on days 0, 128, and 224. Heifers were fitted with a pedometer behind their shoulder on day 0 to record physical activity. Pedometer results and blood samples were collected weekly for progesterone analysis. Hair samples from the tail switch were collected every 28 d. Data were analyzed with pen or pasture as an experimental unit, via ANOVA using the MIXED or GLIMMIX procedures of SAS (SAS Inst. Inc., Cary, NC). Heifers from CON had more (P < 0.01) steps per week compared with DENS and DENS-EX (23,973, 6,706, and 12,354 steps/wk, respectively; SEM = 1,247), and DENS-EX heifers had more (P < 0.01) steps per week compared with DENS. No treatment effects (P ≥ 0.91) were detected for heifer BW gain (~0.820kg/d). Hair cortisol concentrations were greater (P ≤ 0.05) in DENS and DENS-EX compared with CON beginning on day 56. Exit velocity and temperament score were greater (P ≤ 0.05) in DENS compared with DENS-EX and CON on day 224. Puberty attainment was delayed (treatment × day; P < 0.01) in DENS compared with DENS-EX and CON. A greater (P ≤ 0.05) proportion of CON were pubertal by day 105 compared with DENS and DENS-EX (30.0%, 11.6%, and 15.0%, respectively; SEM = 6.5), while a greater (P < 0.05) proportion of CON and DENS-EX were pubertal by day 154 compared to DENS (61.7%, 66.7%, and 43.3%, respectively; SEM = 6.5). Rearing replacement heifers in drylots with high stocking density has detrimental effects on their puberty attainment, and the moderate exercise regimen partially alleviated this negative outcome.

Replacing sulfate with hydroxychloride sources of trace minerals modulated the growth performance and plasma indicators of inflammation and energy metabolism in beef heifers during periods of feed restriction and adaptation to a high-starch diet.

This study evaluated the effects of different sources (sulfate vs. hydroxychloride) of Cu, Mn, and Zn during feed restriction and a high-starch diet on heifer growth performance. On day 0, Nelore heifers (n = 40) were stratified by body weight (BW = 238 ± 38kg) and age (21 ± 1 mo), and individually allocated into 1 of the 40 drylot pens. The study was divided into periods of pen acclimation (days 0 to 27), nutrient surplus (days 28 to 55), nutrient restriction (days 56 to 83), and step-up adaptation to a high-starch diet (days 84 to 112). Heifers had free choice access to Tifton hay (Cynodon sp.) and salt from days 0 to 27. On day 28, 20 heifers/treatment were randomly assigned to receive free choice access to Tifton hay and protein supplementation at 0.10% of BW (dry matter, DM) added with sulfate (SUL) or hydroxychloride (HYD) sources of Cu, Mn, and Zn from days 28 to 112. From days 56 to 83, heifers were offered 50% of the average hay DM intake obtained from days 50 to 55. From days 84 to 112, each respective protein supplement was mixed with a starch-based total mixed ration and the concentrate DM amount was gradually increased every 7 d (starting with 35% concentrate and 65% hay on day 84 and ending with 80% concentrate and 20% hay from days 106 to 112). Effects of treatment × day and treatment were not detected (P ≥ 0.37) for heifer BW, fecal pH, average daily gain (ADG), and DM intake, except for ADG from days 28 to 56, which was less (P = 0.05) for SUL vs. HYD heifers. Effects of treatment × day were detected (P = 0.02) for plasma concentrations of insulin-like growth factor 1 (IGF-1) and haptoglobin. Plasma concentrations of IGF-1 were greater (P ≤ 0.05) for HYD vs. SUL heifers on days 56, 70, 77, 84, and 91. Plasma concentration of haptoglobin was greater (P = 0.05) for SUL vs. HYD heifers on day 63. Effects of treatment × day of the study and treatment were not detected (P ≥ 0.35) for plasma concentrations of cortisol, ß-hydroxybutyrate (BHBA) and non-esterified fatty acids (NEFA). Thus, Nelore heifers offered hydroxychloride sources of Cu, Mn, and Zn exhibited greater plasma concentrations of IGF-1 and a temporary increase in ADG during nutrient surplus compared to those receiving sulfate sources. While hydroxychloride supplementation reduced the acute phase response early in nutrient restriction, it did not improve growth and plasma concentrations of haptoglobin, cortisol, NEFA, and BHBA during nutrient restriction and adaptation to a high-starch diet.

Administering the maternal bovine appeasing substance improves overall productivity and health in high-risk cattle during a 60-d feedlot receiving period.

This experiment evaluated health, physiological, and performance responses of high-risk cattle administered the maternal bovine appeasing substance (mBAS) during feedlot receiving. Angus-influenced, newly weaned male calves (n = 120) were purchased from an auction facility. Calves arrived at the research feedyard on day -1 and body weight (BW) was recorded upon arrival (199 ± 1 kg). Calves were ranked by arrival BW and received 1 of 2 treatments prior to initial processing (day 0): (1) 10 mL of an mBAS (Ferappease; FERA Diagnostics and Biologicals; College Station, TX) or (2) 10 mL of mineral oil (CON; placebo). Treatments were applied topically to the nuchal skin area (5 mL) and above the muzzle (5 mL). Calves were vaccinated against Clostridium and respiratory pathogens, dewormed, implanted, band-castrated, and received metaphylaxis at initial processing, and then distributed into 10 drylot pens according to arrival BW and treatment (n = 12 calves/pen, 5 pens/treatment). Calves were reapplied treatments (mBAS or CON) concurrently with booster vaccination on d 14. Feed intake and incidence of bovine respiratory disease (BRD) were recorded daily. Blood and hair samples from the tail-switch were collected on days 0, 14, 28, 42, and 60 for analysis of physiological variables. Calves were sampled for nasal microbiota analysis via swab on days 0, 14, and 28. Final shrunk BW was recorded on day 61 after 16 h of feed and water restriction. Calf BW gain and final BW did not differ between treatments (P ≥ 0.40). Incidence of BRD was similar (P = 0.99) between mBAS and CON (56.7% for both treatments; SEM = 6.45). A greater (P = 0.04) proportion of mBAS calves diagnosed with BRD required a single antibiotic treatment to regain health (70.6 vs. 47.0%; SEM = 8.32), and mortality was greater (P = 0.03) in CON calves diagnosed with BRD (17.6 vs. 2.94%; SEM = 5.133). Relative abundance of Mycoplasma in nasal microbiota was reduced (P = 0.04) in mBAS calves compared with CON (34.7 vs. 27.4%; SEM = 2.35). Cortisol concentration in hair from the tail-switch was less (P = 0.01) on day 28 for mBAS calves compared with CON. Administering mBAS improved (P = 0.04) total pen-based liveweight change during the experiment (498 vs. 309 kg/pen; SEM = 65.2) and final pen-based total liveweight (2,676 vs. 2,484 kg/pen; SEM = 65.4). Administration of mBAS to high-risk cattle decreased physiological stress markers, reduced mortality, and increased pen-based productivity during a 60-d receiving period.

Multiple administrations of bovine-appeasing substance during a 42-d preconditioning program followed by feedlot receiving and its effects on physiologic, health, and performance responses of feeder cattle.

This experiment evaluated the effects of multiple bovine-appeasing substance (BAS) administration during a 42-d preconditioning program followed by a feedlot receiving period on productivity, health, and physiological variables of feeder cattle. Ninety calves were weaned, weighed, loaded into a livestock trailer, transported for 70 km, and unloaded at the Bozeman Agricultural Research and Teaching Farm for a 42-d preconditioning program. Upon arrival, calf body weight (BW) was recorded again, and both pre- and post-transport BWs were averaged and used as calf weaning initial BW. Calves were ranked by BW, sex, and age in a completely randomized design and assigned to receive 1) multiple administrations of BAS at weaning (day 0), days 14, 28, and before transport and feedlot entry (day 42; BAS; RSEA Group, Quartier Salignan, France; n = 9 pens/treatment), or 2) placebo (diethylene glycol monoethyl ether; CON; n = 9 pens/treatment). Treatments (5mL) were applied to the nuchal skin area of each animal during the preconditioning period. Calves within treatment groups were ranked again by initial BW, sex, and age, in a manner that pens have similar initial BW, age, and three steers and two heifers and allocated to 1 of the18 drylot pens. On day 42, calves were combined within the treatment group, loaded into two different single double-deck commercial livestock trailers, and transported for 1,000 km (approximately 16h). Upon arrival (day 43), calves were unloaded at the same feedyard. Blood samples were collected on days 0, 3, 7, 14, 21, 28, 42, 43, 46, 50, 57, 64, and 90. Average daily gain, final BW, and feed efficiency did not differ (P > 0.52) between BAS and CON calves in the preconditioning and receiving phases. A treatment × day interaction was detected (P < 0.001) for plasma haptoglobin concentrations, which was greater (P < 0.01) in CON on days 3 and 7 vs. BAS calves. During the preconditioning phase, serum NEFA concentration was reduced (P < 0.01) in BAS on day 3 compared with CON calves. A treatment × day interaction was detected (P = 0.001) for exit velocity, which was greater (P < 0.001) for CON vs. BAS calves on days 3, 7, 14, and 21 during the preconditioning phase and on day 46 of the receiving phase. Therefore, Applications of BAS reduced immunological responses and exit velocity associated with stress caused by management practices, but did not improve performance during the preconditioning and receiving phases.