Angus Steers Research Articles

59 Neutrophils and respiratory health of feedlot cattle supplemented with autolized yeast

Abstract The objective of this study was to evaluate whether autolyzed yeast (AY) in the diet interferes with the innate immunity and healthy of feedlot finished steer. At 0, 14, 42, 70, and 105 days of feedlot, the following were measured: neutrophil-lymphocyte ratio (N/L), neutrophilic oxidative metabolism, and respiratory disease indicators (frequency of animal with mucopurulent nasal secretion and orbital temperature) and frequency of pneumonia (histopathological analyses at slaughter day). For this, 36 ½ Angus steers (average BW 330kg and 11 months of age), were distributed in three treatments, with 12 animals each: Control; YA 4g (4g/animal/day, RumenYeast®); and AY 7g (7g/animal/day, RumenYeast®) for 105d. For all results, significant data were considered that show significance level P ≤ 0.05 and statistical trend, 0.05 > P < 0.1. On days 42 and 70, the AY 4g increased neutrophil oxidative metabolism (P = 0.06 and 0.01) and reduced N:L ratio (P = 0.08 and 0.01) comparing to the control group. This neutrophil oxidative metabolism increase was punctual for AY 7g, at 70d (P = 0.01), but the reduction of the N:L ratio occurs at 42 and 70d (P = 0.08 and 0.01). These immune increments promoted fewer respiratory diseases indicators, especially in the AY 4g, observed by a higher frequency of animals without nasal secretion at 42, 70 e 105d comparing to the control group (P = 0.03, 0.001 and 0.001), a lower orbital temperature at 105d (P = 0.02), and a lower frequency of pneumonia (P = 0.06). The AY 7 showed a higher frequency of animals with nasal secretion 14d (P = 0.04) and a lower frequency of animals without mucopurulent nasal secretion at 42 and 70d (P = 0.03 and 0.001), without significant difference for orbital temperature or pneumonia comparing to the other groups. We conclude the autolyzed yeast included in the diet improved the neutrophils functions of the animal and the health of the respiratory tract of feedlot cattle, especially when used at 4g/animal/day.

PSIX-31 The effect of days on feed and trenbolone acetate + estradiol-17β implants on the dimensional measurements of serially harvested steer carcasses

Abstract Charolais x Angus steers (n = 80) were serially harvested to evaluate the effect of days on feed and exogenous growth promotion on dimensional measurements of chilled carcasses. Steers were randomly distributed to treatment and harvest day in a 2 x 10 factorial design. Steers were paired by genetic similarity and randomly assigned one of two treatments; implanted with Revalor-XS (REV) on d 0 and d 190 or non-implanted control (CON). Four pairs were randomly assigned to market endpoints of 0, 42, 84, 126, 168, 210, 252, 294, 336, or 378 DOF. Forty-eight h after harvest, a digital image was obtained of the lateral aspect of the right side of each carcass in front of a grid containing 390 contrasting black and green squares (100 cm2 each). Images were individually calibrated to a common standard and digitally measured for 2-dimensional surface area and maximal carcass length and width. Maximal length was measured from the caudal tip of the hindshank to cranial edge of the foreshank and maximal width was measured from the dorsal edge of the crest to the ventral edge of the foreshank. Carcass dimensional measurements were analyzed using mixed models; fixed effects were implant treatment and DOF with d 0 BW as a covariate. No TRT x DOF interaction was observed (P ≥ 0.13) for any dependent variable. Steers administered REV yielded 516 cm2 greater (P < 0.01) surface area than CON; moreover, surface area increased 21.0 cm2 /day. No TRT effect (P = 0.57) was observed for maximal length, however maximal width was 3.9 cm greater (P < 0.01) for REV steers. Steer carcasses increased 0.16 cm/day in length and 0.07 cm/day in width. These data illustrate growth in carcass size following exogenous growth promotant administration and finishing steers for various lengths of time.

232 Effects of bismuth subsalicylate and encapsulated calcium-ammonium nitrate on beef cattle performance and liver mineral concentration

Abstract The effects of bismuth subsalicylate (BSS) and encapsulated calcium-ammonium nitrate (eCAN) on feedlot beef cattle performance and liver mineral concentration were evaluated. Two hundred Angus steers (BW = 385 ± 27 kg) were used in a randomize complete block design (block = BW) and allocated to 50 pens (4 steers/pen) where treatments were randomly assigned as follows: CTL (urea at 0.70%, 0.28% ruminally available sulfur [RAS]), NIT (eCAN at 2.0%, 0.28% RAS), UBS (urea at 0.70%, BSS at 0.33%, 0.28% RAS), NITBS (eCAN at 2.0%, BSS at 0.33%, 0.28% RAS), and LOW-S (urea at 0.70%, 0.14% RAS). Steers were fed for 171 d and weighed every 35 d. Dry matter intake (DMI) was recorded weekly. Liver biopsies were taken on d -5 and 124 from the same randomly selected animal per pen. The MIXED procedure of SAS was used with the fixed effect of BSS, eCAN, S, BSS × CAN, and the random effect of block. Cattle consuming urea as non-protein nitrogen source (NPNS) had greater final body weight (FBW; P = 0.045) than cattle consuming eCAN. There was a NPNS effect where eCAN reduced DMI (P < 0.001) and average daily gain (ADG; P = 0.041), but did not affect feed efficiency (G:F; P = 0.876). There was a tendency for BSS to reduce DMI (P = 0.095), but not affect ADG (P = 0.436) or G:F (P = 0.876). The effect of S was also observed (P = 0.042) where LOW-S cattle consumed less feed than CTL. A reduction of final liver Cu concentration was observed (P = 0.042) where BSS reduced the concentration of Cu by 58%. Bismuth subsalicylate did not affect cattle performance; however, it might be detrimental to cattle consuming low Cu diets.

PSI-2 Activity and rumination of implanted British × Continental steers vs. non-hormone treated counterparts consuming various levels of roughage throughout a 361-d growth window

Abstract A serial-harvest study was conducted to evaluate rumination and activity of growing steers in response to implant and dietary roughage. Charolais×Angus steers (n = 80) were randomized to harvest (0, 42, 84, 126, 168, 210, 252, 294, 336 or 378 DOF) and implant treatment (REV: Revalor-XS on d-0 and d-190 or CON: no implant). Activity and rumination were objectively monitored by SCR accelerometers attached to the left ear. Steers consumed 3 rations throughout the study: starter (38.5% roughage), intermediate (23% roughage), and finishing (8.5% roughage). Data was logged in 2-h increments from 77 steers across 361 d and analyzed using mixed models. Rumination and activity varied (P < 0.01) within 24-h, exhibiting bimodal patterns; rumination peaked at 0600 and 1400 h and troughed at 1000 and 1800 h. Activity peaked at 0800 and 1800 h and troughed at 0400, 1200–1400, and 2200 h. Steers administered REV ruminated less (364 vs 380 min/d; P = 0.04) than CON; however, 24-h activity was similar (P = 0.29) among treatments. Treatment×roughage interactions (P < 0.01) occurred for rumination and activity. Rumination tended to differ (P = 0.06) between CON consuming 38.5% and 23% roughage, however, CON steers ruminated (P < 0.01) more than REV when consuming 8.5% roughage. Implanted and non-implanted steers ruminated less (P < 0.01) as roughage inclusion decreased from 38.5% and 23% to 8.5% (457 and 439 vs 317 min/d) in the finishing ration. Activity was highest for steers consuming 38.5% roughage and was similar (P > 0.05) among treatments; however, activity decreased (P < 0.01) upon transition to 23 and 8.5% roughage. Activity peaks and troughs can be attributed to processing days and weather events. Implanted steers consuming 8.5% roughage were more active (342 vs. 337 and 333 min/d; P < 0.01) than CON and REV steers consuming 23% roughage. In conclusion, rumination and activity are responsive to hour, dietary roughage and growth-promoting implants.

191 Effects of injectable vitamin C at weaning and prior to transit on growth performance and immune function of beef steers

Abstract Ninety-one early-weaned (65 ± 11 d) Angus steers (92 ± 4 kg) were blocked by age to a 2 × 2 factorial examining effects of injectable vitamin C (VC) at weaning and/or prior to transport to the feedlot on antibody titers and growth performance. Injections (20 mL/steer) of VC (250 mg sodium ascorbate/mL) or saline (SAL) were given at time of weaning on d 0 (WEAN) and/or prior to a 6 hr trucking event to a feedlot on d 49 (TRANS). Steers were given booster vaccinations on d 0. Steers were weighed on d 0, 1, 14, 48, 49, 64, 106, and 107. Blood was collected (12 steers/treatment) on d 0, 1, 2, 14, 49 (pre- and post-transit), 50, and 51. Data were analyzed via Proc-Mixed of SAS (experimental unit = steer; n = 22–23/treatment) with fixed effects of block, WEAN, TRANS, and WEAN × TRANS. Plasma ascorbate concentrations for weaning (d 0, 1, and 2) and transit (d 49-pre-trucking, 49-post-trucking, 50, and 51) were analyzed as repeated measures (repeated effect = day). Plasma ascorbate concentrations were greater on d 1 and 2 for steers that received VC at weaning (VC = 19.6, SAL = 8.8 ± 1.26 µM; WEAN × day P < 0.01). Similarly, ascorbate concentrations were greater on d 49 post-trucking, 50, and 51 for steers that received VC pre-transit (TRANS × day P = 0.01). Treatments did not affect bodyweight or average daily gain throughout the trial (P > 0.32). There were no effects of treatment on serum Bovine Viral Diarrhea Virus type 2 antibody titers on d 14 or 51 (P > 0.33). An injection of VC administered to early weaned beef steers at weaning or pre-transit increases plasma ascorbate concentrations but does not improve growth performance or antibody response to vaccination booster.

PSII-27 Effect of endophyte-infected tall fescue seed and red clover isoflavones on the serum metabolites in beef steers

Abstract Fescue toxicosis reduces animal performance, costing approximately $2 billion dollars to the beef industry annually. Emerging research has demonstrated effects of fescue toxicosis can be reduced by consumption of red clover isoflavones. The objective of the current study was to evaluate the effect of isoflavone supplementation with endophyte infected seed consumption on serum metabolites in beef steers. Angus steers (n = 36) were randomly allocated to treatments in a 2×2 factorial arrangement of endophyte-infected (E+) or endophyte-free (E-) tall fescue seed, with (P+) or without (P-) a red clover isoflavone supplement. For the 21d trial, steers were provided a basal diet supplemented with fescue seed head targeting a minimum of 0.011 mg×kg of body weight−1×d−1 of total alkaloids. A total of 943 mg isoflavones were administered daily via bolus. Following the 21d trial, blood samples were collected for metabolite analysis. Metabolites were filtered from serum and extracted using 0.1% formic acid in acetonitrile:water:methanol (2:2:1) for analysis on the Dionex UltiMate 3000 UHPLC system and Exactive Plus Orbitrap MS. The Metabolomic Analysis and Visualization Engine program was used to determine peaks and identify metabolites. Resulting metabolite data were analyzed in MetaboAnalyst 4.0 and SAS 9.4 with significance at P≤0.05. Principle component analysis indicated separation of metabolomes between E+P+ and E-P- steers. Orthogonal partial least squares discriminant analysis depicted distinct separation between P+ and P- steers and partial separation between E+ and E- steers. The variation between P+ and P- metabolomes were mainly due to differences in citrulline (r = 0.47, P = 0.003), and AMP (r = -0.35, P = 0.03) between E+ and E- metabolomes. A total of 13 and 8 metabolic pathways were impacted from differences in seed type and isoflavone treatment, respectively (P ≤ 0.05). Therefore, metabolism is altered by isoflavone supplementation that may improve animal performance during fescue toxicosis.

PSI-5 Comparison of ninth-tenth-eleventh rib section to carcass components in serially harvested steer carcasses

Abstract The objective of this study was to compare separable lean, fat and bone of samples taken from the ninth-tenth-eleventh rib section to those of the carcass. Charolais x Angus steers (n = 80) were randomized to implant treatments (REV: Revalor-XS on d-0 and d-190 or CON: no implant) and harvest date in a 2x10 factorial design. Four pairs of steers were randomly allocated to one of 10 harvest dates and harvested in 42d intervals (0, 42, 84, 126, 168, 210, 252, 294, 336, and 378). Carcass yields were determined by fabricating the right side of each carcass and separating lean, fat, and bone components and weighing to the nearest +/- .05 kg. Ninth-tenth-eleventh rib sections were collected from the left side of each carcass, dissected into lean, fat, and bone, and weighed to the nearest +/- .005 g. Regression models were created to determine linear associations between rib sections and carcass parameters. Carcass fat and lean were strongly correlated (r = 0.87 and 0.80 respectively) to 9-10-11 fat and lean, however carcass bone was only moderately correlated (r = 0.59) to 9-10-11 bone. Rib sections were representative of a whole carcass supporting use of this method to predict carcass composition of beef cattle.

275 Phenotypic relationships between heart score and feed efficiency, carcass, and pulmonary arterial pressure traits

Abstract Pulmonary hypertension (PH) can lead to premature mortality in fed cattle and is often called Feedlot Heart Disease (FHD). To date, pulmonary arterial pressure (PAP) has been the only indicator trait of PH that has been evaluated. The objective of this study was to evaluate relationships between heart score (using heart score as a phenotype for PH) and PAP, carcass, and feed efficiency traits in fattening Angus steers. Our hypothesis was that feed efficiency and carcass traits, along with PAP, would demonstrate a strong relationship with heart score. Feed efficiency, carcass, PAP and heart score data from 89 Black Angus steers from Colorado State University Beef Improvement Center were collected and used for this study. Evaluations were performed using a multiple linear regression model, which included heart score as a categorical fixed effect and age as a continuous fixed effect. Least Square Means, pairwise comparisons, and ANOVA tables were constructed per trait. PAP (P < 0.001) showed an important relationship to heart score and average dry matter (P < 0.10) intake approached importance to heart score. In general, feed efficiency and carcass traits decreased as heart score increased, but PAP was the only trait with a strong relationship to heart score (P < 0.05). This led us to reject our hypothesis.

PSI-3 Allometric Growth Coefficients of Non-Carcass and Carcass Components of Serially Harvested Implanted and Non-Implanted Steers

Abstract The objective of this study was to quantify allometric growth coefficients of non-carcass and carcass components of implanted or non-implanted Charolais×Angus steers in relation to empty body weight. Steers (n = 80; initial BW 271±99 kg) were paired, randomized to harvest date (d 0-42-84-126-168-210-252-294-336-378), and CON (negative control) or REV (Revalor-XS on d 0 and 190) treatments. Weights were log transformed and consolidated to arithmetic means by treatment and harvest date. Growth coefficients were calculated using the log transformed allometric equation Y=K+aX where Y=log(part), X=log(whole), A=log(slope), and K=log(intercept), where empty body growth = 1. Coefficients by treatment were analyzed via independent t-test. Kidney (0.58 vs 0.51; P=0.06) and lungs/trachea (0.52 vs 0.46; P = 0.09) tended to grow faster for REV, and pituitary glands grew numerically faster (P = 0.82) for REV (0.71 vs 0.56). Non-carcass components with lowest growth coefficients included small intestine (0.02), large intestine (0.12), and brain/spinal cord (0.13), whereas kidney-pelvic-heart fat (2.01) accumulated quickly. Growth coefficients of primals were numerically greater for REV steers, except in the rib. All primals except round (0.81) and foreshank (0.87) exhibited coefficients greater than 1 (brisket, 1.18; chuck, 1.03; rib, 1.18; plate, 1.45; loin, 1.04; and flank, 1.47). Growth coefficients were greater (P< 0.01) for REV in two subprimals (chuck eye roll, 0.87; eye of round, 0.75), CON was greater (P < 0.01) in one subprimal (flank steak, 0.79). Pectoral meat (0.19), bottom sirloin flap (0.56), and heel meat (0.59) exhibited growth coefficients less than 1. Although not significant, total lean was deposited more quickly in REV (0.95 vs 0.88; P=0.45), whereas total fat (2.17 vs 1.98; P=0.35) and total bone (0.92 vs 0.75; P=0.29) were faster growing for CON. These data indicate fat exhibits greatest growth coefficients compared to the empty body; whereas, there were minimal differences in growth coefficients in regards to treatment.

216 Autolysed yeast supplementation in finishing beef steers diets during feedlot

Abstract The objective of this study was to evaluate the productive performance, the ingestive behavior, the apparent digestibility of the feed, and the carcass characteristics of finishing beef steers during feedlot under different inclusions of autolyzed yeast (AY). For this, 36 ½ Angus steers (average BW 330 kg and 11 months of age), were distributed in a completely randomized way, consisting of three treatments and six replications (of two animals each): T1 - Control; T2 – AY 4g (diet with 4 g/animal/day of AY Saccharomyces cerevisiae product RumenYeast®), and T3 – AY 7g (diet with 7 g/animal/day of RumenYeast®), for 105 days, being 14 days of adaptation, two periods of 28 days and 1 of 35 days. The performance was evaluated, as well as the apparent digestibility of the diet, at the end of the 1st and 3rd periods with the total collection of feces. The carcass gain in the period was also calculated, and the thickness of fat on the Longissimus dorsi muscle was measured, as well as on the front, side, and back, using a digital caliper. The data were submitted to analysis of variance and the means compared to 5% of significance. The supplementation of AY 4g promoted higher daily BWG and better FCR during the adaptation feedlot period (P < 0.05), and the AY 7g did not differ from the other treatments. The animals that received AY ended up with higher fat thickness in the carcass than the control group (P < 0.05). The apparent digestibility of diets containing AY was higher than the control diet (P < 0.05). Based on these results, the supplementation of AY 4g yielded positive results in the initial phase of the feedlot, improved the apparent digestibility of DM, and resulted in better carcass finishing.

PSIX-24 Comparison of serial real-time A-mode vs. B-mode ultrasound fat depth measures on prediction of final carcass value endpoints

Abstract Charolais x Angus steers (n = 80) were evaluated across a 378-day feeding period in response to administration of a growth promoting implant containing trenbolone acetate (TBA) and estradiol (E2) using A-mode and B-mode ultrasound. Steers were scanned at 42-d intervals (0, 42, 84, 126, 168, 210, 252, 294, 336) during 10 separate ultrasound scanning sessions 24-h prior to harvest. Ultrasound B-mode rump fat images (BRFU) were obtained by a certified Ultrasound Guidelines Council (UGC) technician using an ALOKA 500V console equipped with a 17.2 cm carcass probe. Ultrasound A-mode images (ARFU) were obtained by a non-UGC certified technician using a RENCO Lean Meater. Images of BRFU were analyzed by the CUP lab whereas ARFU image results were determined chute side by the scanning technician. Carcasses were dissected into total lean, fat and bone post-harvest. Rump fat thickness ultrasound measurements were compared to carcass traits used to determine carcass value. Carcass endpoints included 12th–rib fat thickness (FTC), 12th rib-eye area (REAC), marbling score (MARB), and total percentage of carcass fat (PCF). The correlation between BRFU and ARFU was 0.70 (P < 0.01). Positive correlations (P < 0.01) between ultrasound rump fat measures taken the day before harvest and carcass measurements indicated moderate relationships between BRFU and FTC (r=0.80); BRFU and REAC (r=0.66); BRFU and MARB (r=0.68); BRFU and PCF (r=0.75); ARFU and FTC (r=0.69); ARFU and REAC (r=0.76); ARFU and MARB (r=0.79); and ARFU and PCF (r=0.80). These results indicate A- and B-mode ultrasound measures of rump fat may be adequate measures for estimation of total percent carcass fat.

PSXI-19 Investigating the Relationship Between Temperament and Performance Traits in Feedlot Cattle

Abstract Temperament in cattle, is defined as behavioral changes in response to humans or changes in the environment, and has been associated with reduced feed efficiency, reduced growth rate, and poor feedlot health. The objective of the study was to determine if temperament affected the performance, growth and health of feedlot cattle. One-hundred and thirty-one Angus x Simmental steers from a single ranch were sampled at a commercial feedlot in Chappell, NE. Blood samples for metabolite analysis, exit velocity, and blood lactate concentration for temperament classification were collected in addition to feedlot performance data and carcass quality measurements. The GLM and LSM procedures of SAS (SAS 9.4, 2014) were used to evaluate differences between temperament classifications. Pearson correlations were calculated between temperament and performance variables. Steers were divided into three exit velocity classifications, with fast animals (n = 27) having exit velocity greater than one standard deviation from the mean and slow animals (n = 26) having exit velocities lower than one standard deviation from the mean. Feed intake and behavior was monitored for 42 days with GrowSafe feed bunks and average daily gain, dry matter intake and residual feed intake calculated. There were significant differences between the temperament classifications of fast, medium and slow for both exit velocity and blood lactate (P < 0.0001), indicating there was a difference in responses from the classifications. Exit velocity had no effect on any of the growth parameters measured. There was a significant positive correlation between exit velocity and blood lactate (P < 0.0001). RFI was significantly correlated with exit velocity (P = 0. 051) and blood lactate (P < 0.05). This suggests that animals with higher RFI or less efficient animals had more flighty temperaments as determined by blood lactate and exit velocity.

207 Effects of increasing dietary metabolizable protein in lightweight beef calves

Abstract The objective was to assess the effect of increasing metabolizable protein (MP) supply to lightweight beef steers on total tract digestion, N balance, and performance. The 2016 Beef Cattle Nutrient Requirements Model (BCNRM) prediction of MP requirements in lightweight beef steers (less than 250 kg) is limited by available data. Spring-born Angus steers (n = 12; BW = 166 +/- 10.7 kg) were weaned at 97 ± 10 d of age, backgrounded 42 d, implanted with Component TE-IS, stratified by BW, and assigned to one of four treatments in a crossover design with two 19 day periods. Each period included a 12-day adaptation followed by a 6-day collection period of total orts, feces, and urine. Treatment diets were formulated to provide 0.62 (MP1), 0.76 (MP2), 0.89 (MP3), and 1.01 (MP4) kg MP per day. Metabolizable energy was similar across diets (2.14 Mcal/kg). Data were analyzed using the Mixed procedure of SAS. Dry matter intake was not affected by treatment (P = 0.92) and averaged 5.7 kg per d. Average daily gain (ADG) tended (P = 0.06) to increase quadratically with MP provision with 1.45, 1.72, 1.93, and 1.71 kg per day for MP1, MP2 MP3, and MP4, respectively. Feed efficiency (G:F) also increased quadratically (P = 0.05) at 0.27, 0.32, 0.35, and 0.31 for MP1, MP2 MP3, and MP4, respectively. Greater dietary MP linearly increased (P < 0.01) N intake, N absorption, and urinary N. Fecal N and retained N were not affected by treatment (P ≥ 0.56). Apparent organic matter digestibility increased linearly (P ≤ 0.01). Increasing MP resulted in a linear increase in N absorption but a quadratic response for ADG, suggesting MP greater than 0.89 kg per d may exceed MP requirements for steers weighing 166 kg and consuming a 2.14 Mcal/kg diet.

223 The effects of supplemental zinc and ractopamine hydrochloride on the Longissimus dorsi proteome of finishing beef steers

Abstract The objective of this study was to determine how steer growth rate and Zn nutrition affects the muscle proteome. Forty-eight, high percentage Angus steers (494 ± 18.2 kg) were blocked by BW and GeneMax gain score (GeneMax Focus, Zoetis, Parsippany, NJ) to treatments arranged in a 2×2 factorial. On d 0, steers were assigned to control (CON; 36 mg Zn/kg dry matter [DM]) or supranutritional Zn (SUPZN; CON + 60 mg Zn/kg DM as ZnSO4+ 60 mg Zn/kg DM as Zn-amino acid complex) dietary treatment (ZNTRT), and housed in pens (n = 6 or 8 steers/pen) with Growsafe bunks. On d 62, within ZNTRT steers were assigned to ractopamine hydrochloride treatments (RACTRT) of 0 (NO) or 300 mg·steer-1·d-1(RAC) for 28 d. Longissimus dorsi biopsies (between 12thand 13thrib) were collected on d 77. Sarcoplasmic fractions were extracted and submitted for proteomics analysis using mass spectrometry (LC-MS/MS). Data were log transformed and comparisons made using t-tests with adjusted P-value cutoffs of 0.1. Differences were noted in abundance of proteins involved in glycolytic, retinol and fatty acid metabolism. A shift from slow to fast muscle fiber type was suggested by decreased abundance of myoglobin and slow skeletal troponin 1 in steers fed RAC compared to steers not fed RAC within CON (P ≤ 0.04), while these proteins also tended to be lesser due to SUPZN within steers not fed RAC (P ≤0.09). The intermediate filament associated protein, vimentin, tended to be less abundant in RAC steers (P ≤ 0.09), suggesting RAC affects cellular remodeling. Proteins involved in immune function were also affected; for instance, the acute phase protein alpha-1-acid glycoprotein was more abundant in CON-RAC compared to either SUPZN-RAC (P = 0.001) or CON-NO (P = 0.02). Ractopamine hydrochloride and supranutritional Zn, independently and collectively, affect proteins involved in muscle metabolism, cellular remodeling and immune function in beef steers.

PSIX-9 Impacts of bunk management on feedlot performance, carcass characteristics, hydrogen sulfide concentration and blood oxygen saturation in steers fed 25 or 50% modified distillers grains plus solubles

Abstract One hundred and twenty-six yearling angus steers (initial body weight 445.87 ± 7.13 kg) were utilized in a 2 x 2 factorial design to evaluate the impacts of bunk management and modified distillers grains plus solubles (mDGS) inclusion on feedlot performance, hydrogen sulfide concentrations and blood oxygen saturation. Treatments included bunk management strategy either control bunk management (CON; clean bunks at the time of next day’s feeding) or long bunk management (LONG; feed remaining at time of next day’s feeding), and two inclusion rates of mDGS either 25% or 50% (DM Basis). On d 0, 7, 14, 21, 28 and 35 rumen gas samples were collected via rumenocentesis, and arterial blood samples were collected on two steers from each pen. No differences (P ≥ 0.09) were observed for dry matter intake, average daily gain and gain-to-feed ratio for bunk management or mDGS inclusion. Hot carcass weight, ribeye area, marbling score and quality grade were not affected (P ≥ 0.48) by either bunk management or mDGS inclusion. Back fat was greater (P = 0.04) for CON steers compared to LONG (1.30 vs 1.12 ± 0.05cm, respectively), but was not affected (P = 0.59) by mDGS inclusion. Steers on CON had greater (P = 0.03) yield grades compared to LONG (3.21 vs 2.96 ± 0.11, respectively). Bunk management strategy did not impact hydrogen sulfide concentrations or blood oxygen saturation (P = 0.82). Hydrogen sulfide concentrations increased (P < 0.001) with increasing mDGS inclusion. Blood oxygen saturation was influenced by day of sampling (P = 0.01). Blood oxygen saturation was not affected (P = 0.07) by mDGS inclusion. The fact that ruminal hydrogen sulfide concentrations increased while blood oxygen saturation remained similar raises questions about the quantity of hydrogen sulfide and metabolic fate of excess hydrogen sulfide in the blood of ruminant animals.

PSV-32 Pulmonary arterial pressure in cattle influences beef color during retail display

Abstract Pulmonary hypertension is a noninfectious disease of cattle at altitudes > 1524 m (5,000 ft). Mean pulmonary arterial pressures (mPAP) ≥ 50 mmHg is used as an indicator for pulmonary hypertension in cattle. Meat quality attribute, such as color, critically influencing consumer purchase decision, is economically significant. However, the effect of pulmonary arterial pressures (PAP) on postmortem beef color has not been investigated. To examine this, instrumental color, metmyoglobin reducing activity (MRA), and lipid oxidation of aged strip loins (longissimus lumborum; LL) steaks from high PAP (98±13; n = 5) and low PAP score (41±3; n = 6) fattened Angus steers (i.e., live weight of ~600 kg) were evaluated during simulated retail display (day 1, 3, 5, 7, 9). A split-plot design was used to analyze the effects of PAP score and display day on instrumental color, MRA, and lipid oxidation. Data analysis was performed using R with the lme4 package as a mixed model, where PAP score (high or low), display day, and their interactions were the fixed effects, and random effect was individual steer. Differences between least square means (P < 0.05) were determined by Tukey’s multiple comparisons. An interaction (P < 0.05) between PAP score and display day for redness (a* value), chroma, hue, and MRA was observed. The LL steaks from high PAP score animal had lower (P < 0.05) redness, chroma, and hue, than from low PAP score steer on day 9. A main effect (P < 0.05) of display day on lipid oxidation of was observed, with lipid oxidation increasing as display days increased. The results of current study indicated that the LL steaks from steers with high PAP score have lower color stability than those from steers with low PAP score during simulated retail display. Research partially supported by USDA-NIFA grant: 2018-67015-28241.

PSXII-7 Supplementing beef cattle finishing diets with ruminal protected live yeast affected fatty acid profiles in meat

Abstract Fatty acid (FA) composition in beef is related to beef quality and human health. It was recently reported that feeding active dried yeast (ADY) in finishing bull altered some FA of longissimus muscle. The objective was to evaluate the effects of adding ruminally protected versus non-protected ADY on FA profiles of the pars costalis diaphragmatis (PCD) muscle of beef cattle. Seventy-five Angus steers (initial BW 448 kg) were assigned to a randomized complete block design with five treatments: control (no additives), antibiotics (ANT, 330 mg monensin + 110 mg tylosin/d), ADY (1.5 g/d), encapsulated ADY (EDY, 3 g/d) and combination of ADY and EDY (MDY). The encapsulated ADY consisted of 1.5 g ADY and 2 g capsule. Antibiotics, ADY and EDY were top-dressed to a diet containing 10% barley silage and 90% barley concentrate (DM basis). The PCD samples were collected from cattle at slaughter. Intakes (g/d) of total FA (144), saturated FA (SFA; 41), monounsaturated FA (MUFA, 16) and polyunsaturated FA (PUFA, 87) were not different among treatments. Proportion of SFA (49.0%) and MUFA (48.2%) in PCD did not differ among treatments, whereas the proportion of PUFA was greater (P < 0.05) with EDY (3.0%) and MDY (3.0%) than control (2.4%). The proportion of n-3 FA also tended (P < 0.06) to be greater with EDY (0.49%) and MDY (0.50%) than control (0.41%) and ADY (0.41%). Steers fed EDY and MDY enhanced (P < 0.05) the proportion of linoleic acid (LA n-6) and decosapentaenoic acid (DPA n-3) compared with control. These results indicated that feeding EDY and MDY increased amounts of PUFA, FA n-3, LA n-6 and DPA n-3. Inclusion of encapsulated yeasts to diet might increase the amount of bioactive yeasts reached intestines and result in better utilization of PUFA from the digesta and increase the accumulation in the intramuscular fat.

186 Hormone content of anabolic implants differentially affects plasma and liver trace mineral concentrations

Abstract Forty-eight commercial Angus steers (327 ± 25 kg) were utilized to determine effects of varying implant hormone composition on liver and plasma trace mineral concentrations. Implant (IMP) treatments (n = 12/treatment) included: no implant (CON), estradiol (E2; Compudose; 25.7 mg estradiol; Elanco Animal Health; Greenfield, IN), trenbolone acetate (TBA; Finaplix H; 200 mg trenbolone acetate; Merck Animal Health; Madison, NJ), and a combination of estradiol and trenbolone acetate (ETBA Revalor-S; 24 mg estradiol + 120 mg trenbolone acetate; Merck Animal Health). Cattle were fed forage-based step up rations throughout the sampling period. Plasma samples were collected on d 0, 2, 10 and 30, with liver biopsies collected on d 2 and 10. Data were analyzed with ProcMixed of SAS with fixed effect of IMP. Contrast statements for each treatment vs CON were developed. Plasma trace mineral analysis utilized repeated measures (repeated effect = day). No IMP × Day effects (P ≥ 0.18) on plasma trace mineral were observed. Day 2 liver Zn and Cu and d 10 liver Mn were lesser (P ≤ 0.04) for TBA implanted steers than CON and d 2 liver Mn tended to be lesser (P = 0.06). The Mn response may reflect changes in protein metabolism due to TBA. However, E2 and ETBA tended to have greater (P ≤ 0.07) d 10 liver Fe concentrations than CON while plasma Fe was unaffected (P ≥ 0.75) by E2, TBA, or ETBA. Both d 2 liver and plasma Zn were lesser for ETBA than CON (P ≤ 0.04) likely driven by the TBA in the implant. Implant contrasts did not affect (P ≥ 0.13) other plasma or liver trace mineral concentrations. These data indicate implant strategies, and thus hormones differentially influence trace mineral metabolism in feedlot steers, which may have implications for diet formulation.

189 Evaluation of Hybrid Rye on Growth Performance, Carcass Traits, and Efficiency of Net Energy Utilization in Finishing Steers

Abstract Predominately Angus steers (n = 240, initial shrunk BW 404 ± 18.5 kg) were used in a 117d feedlot experiment to evaluate the effect of hybrid rye (KWS Cereals USA, LLC, Champaign, IL; Rye) as a replacement for dry-rolled corn (DRC) on growth performance, carcass traits, and comparative net energy value in diets fed to finishing steers. Rye from a single hybrid (KWS Bono) with an ergot alkaloid concentration of 392 ppb was processed with a roller mill to a processing index (PI) of 78.8 ± 2.29. Four treatments were used in a completely randomized design (n = 6 pens/treatment, 10 steers/pen) where DRC (PI = 86.9 ± 4.19) was replaced by varying proportions of Rye [DRC:Rye, DM Basis (60:0), (40:20), (20:40), and (0:60)]. Liver abscess scores and carcass characteristics were collected at the harvest facility. Carcass-adjusted performance was calculated from HCW/0.625. Performance-adjusted NE was calculated using carcass-adjusted ADG, DMI, and mean equivalent shrunk BW with the comparative NE values for Rye calculated using the replacement technique. Data were analyzed using the GLIMMIX procedure with pen as the experimental unit. Means were separated using linear and quadratic contrasts. Replacing DRC with Rye linearly decreased (P ≤ 0.01) carcass-adjusted final BW, ADG, DMI and G:F. Feeding Rye linearly decreased HCW and LM area (P ≤ 0.04). Distributions of liver scores and USDA grades for quality and yield were unaffected by treatment (P ≥ 0.09). Using observed performance from d 19 to d 117 (period when steers were on final diet), the estimated replacement NEm and NEg values for Rye were 1.93 and 1.26 Mcal/kg, respectively. Rye can be a suitable feed ingredient in finishing diets for feedlot steers with the optimal inclusion in this experiment at 20% of DM. Complete replacement of DRC with Rye depressed DMI, ADG, and G:F.

104 Effects of nutritional management and implant strategies on growth and carcass performance of steers selected for superior marbling

Abstract A 187-day study utilizing Angus steers (283±4.4 kg) in a 2 x 2 factorial examined the effects of diet and implant strategy on growth and carcass performance of steers selected from Iowa State’s Angus herd genetically selected for enhanced marbling. Factors included diet: finishing (63 NEg; 12% roughage; FIN) or backgrounding (57 NEg, 30% roughage) fed for first 70 days before transitioning to finishing diet (BKG) and implant strategy (IMP): single, long duration implant administered on d0 (Synovex One Feedlot, Zoetis; ONE) or a multiple, regular duration implant strategy (Synovex S on d0, Synovex Choice on d70 and d155, Zoetis; SCC) designed to match trenbolone acetate delivery of 200 mg. Steers were stratified to treatment by marbling potential and initial body weight, and fed via bunks that captured individual steer feed disappearance (n = 15 steers/treatment). Carcass ultrasound, including percent intramuscular fat (IMF), was collected on d0, 70, 155, and 187. Data were analyzed in Proc Mixed of SAS with fixed effects of diet, IMP, and interaction. Initial weight was covariate for performance data, and initial IMF was covariate for IMF analysis. Steers fed BKG had greater DMI, lower ADG, and decreased G:F (P< 0.01) during first 70 days versus FIN. Implant strategy had no effect on growth at d0-d154. From d155-d187, IMP affected ADG (P=0.01) with ONE having lesser ADG, while BKG had greater ADG than FIN. ONE had greater marbling and IMF (P=0.01) on d187 than SCC, suggesting greater IMF deposition during the final re-implant period (d155-d187) and reinforcing the importance for timing of implant administration. Regardless of IMP or diet, steers selected for enhanced marbling graded 100% Choice and higher with 65% of carcasses grading Prime, suggesting potential for using implants to increase efficiency without sacrificing carcass quality.