Angus Steers Research Articles

Effect of continuous or intermittent feeding of ergot contaminated grain in a mash or pelleted form on the performance and health of feedlot beef steers.

This study evaluated the effect of feeding ergot contaminated grain continuously or intermittently through backgrounding (BG) and finishing (FN) in a mash or pelleted supplement on the growth performance, health and welfare parameters, and carcass characteristics of feedlot beef steers. Sixty black Angus steers (300 ± 29.4kg BW) were used in a complete randomized 238-d study. Steers were stratified by weight and randomly assigned to four different diets (15 steers/treatment) and individually housed. Treatments included: (1) control [CON; no added ergot alkaloids (EA)], (2) continuous ergot mash (CEM; fed continuously at 2mg total EA/kg of DM), (3) intermittent ergot mash (IEM; fed at 2mg total EA/kg of DM, during the first week of each 21-d period and CON for the remaining 2wk, this feeding pattern was repeated in each period), and (4) intermittent ergot pellet (IEP; fed at 2mg of total EA/kg of DM as a pellet during the first week of each 21-d period and CON for the remaining 2wk as described for IEM). Steers were fed barley based BG diets containing 40% concentrate:60% silage (DM basis) for 84 d (four 21-d periods), transitioned over 28 d (no ergot fed) to an FN diet (90% concentrate:10% silage DM basis) and fed for 126 d (six 21-d periods) before slaughter. In the BG phase, steer DMI (P < 0.01, 7.45 vs. 8.05kg/d) and ADG (P < 0.01) were reduced for all EA diets compared to CON. The CEM fed steers had lower ADG (P < 0.01, 0.735 vs. 0.980kg) and shrunk final BW (P < 0.01, 350 vs. 366kg) than CON. CEM had lower gain:feed (P < 0.07, 0.130 vs. 0.142) than CON. In the FN phase, steer DMI (P < 0.01, 9.95 vs. 11.05kg/d) and ADG (P = 0.04) were also decreased for all EA fed steers compared to CON. Total shrunk BW gain (P = 0.03, 202.5 vs. 225.2kg), final BW (P = 0.03, 617.9 vs. 662.2kg), and carcass weight (P = 0.06) decreased for all EA fed steers compared to CON. The percentage of AAA carcasses decreased for all EA fed steers (P < 0.01, 46.7 vs. 93.3%) compared to CON. EA fed steers had increased rectal temperatures (P < 0.01, 39.8 vs. 39.4 °C) compared to CON. Pelleting ergot contaminated grain did not reduce the impact of ergot alkaloids on any of the measured parameters during BG or FN. Continuously or intermittently feeding ergot contaminated diets (2mg total EA/kg of DM) significantly reduced intake, growth performance, and carcass weight, with minimal impact on blood parameters in feedlot steers. Pelleting was not an effective method of reducing ergot toxicity.

The impact of sire breed on feedlot performance and carcass characteristics of beef × Holstein steers.

Dairy herds are mating a portion of cows to beef cattle semen to create a value-added calf. Objectives of this study were to compare the feedlot performance and carcass characteristics of beef × Holstein steers by breed when sires represented bulls with commercially available semen. Three groups of single-born, male calves (n = 262) born to Holstein dams on 10 Pennsylvania dairies were sourced during 3 yr. Steers were sired by seven beef breeds: Angus, Charolais, Limousin, Hereford, Red Angus, Simmental, and Wagyu. Steers were picked up within a week of age and raised at two preweaned calf facilities until weaning (8 ± 1wk of age) under similar health and management protocols. Steers were then transported to a commercial calf growing facility where they were managed as a single group until 10 ± 2 mo of age when they were moved to be finished at the Pennsylvania Department of Agriculture's Livestock Evaluation Center feedlot. Groups of steers were selected for slaughter based on body weight. Carcass characteristics were evaluated by trained personnel and a three-rib section of the longissimus muscle (LM) was collected from each carcass for Warner-Bratzler shear force (WBSF) evaluation and intramuscular fat determination. Steers sired by all sire breeds except for Limousin had greater average daily gain (ADG; 1.62 to 1.76kg/d) than Wagyu × Holstein steers (1.39kg/d; P < 0.05). Angus-sired steers had an 8.6% greater ADG than Red Angus-sired steers (P < 0.05). Angus, Charolais (1.73kg/d), and Simmental-sired steers (1.68kg/d) also had greater ADG than Limousin-sired steers (1.55kg/d; P < 0.05). Wagyu × Holstein steers spent 5 to 26 more days on feed (P < 0.05) than Limousin × Holstein, Simmental × Holstein, Angus × Holstein, and Charolais × Holstein steers. Angus and Charolais-sired steers were also on feed for 19 and 21 d fewer, respectively, than Limousin-sired steers (P < 0.05). Red Angus-sired steers had greater marbling scores than Simmental and Limousin-sired steers and Angus and Charolais-sired steers had greater marbling scores than Limousin-sired steers (P < 0.05). Angus, Limousin, and Hereford-sired steers produced the most tender LM as evaluated by WBSF; Angus-sired carcasses (3.82kg) were more tender than Charolais (4.30kg) and Simmental-sired carcasses (4.51kg; P < 0.05). Limousin and Hereford-sired steers (3.70 and 3.83kg, respectively) also had more tender steaks than Simmental-sired steers.

Predicting fat cover in beef cattle to make on-farm management decisions: a review of assessing fat and of modeling fat deposition.

Demands of domestic and foreign market specifications of carcass weight and fat cover, of beef cattle, have led to the development of cattle growth models that predict fat cover to assist on-farm managers make management decisions. The objectives of this paper are 4-fold: 1) conduct a brief review of the biological basis of adipose tissue accretion, 2) briefly review live and carcass assessments of beef cattle, and carcass grading systems used to develop quantitative compositional and quality indices, 3) review fat deposition models: Davis growth model (DGM), French National Institute for Agricultural Research growth model (IGM), Cornell Value Discovery System (CVDS), and BeefSpecs drafting tool (BeefSpecsDT), and 4) appraise the process of translating science and practical skills into research/decision support tools that assist the Beef industry improve profitability. The r2 for live and carcass animal assessments, using several techniques across a range of species and traits, ranged from 0.61 to 0.99 and from 0.52 to 0.99, respectively. Model evaluations of DGM and IGM were conducted using Salers heifers (n = 24) and Angus-Hereford steers (n = 15) from an existing publication and model evaluations of CVDS and BeefSpecsDT were conducted using Angus steers (n = 33) from a research trial where steers were grain finished for 101 d in a commercial feedlot. Evaluating the observed and predicted fat mass (FM) is the focus of this review. The FM mean bias for Salers heifers were 7.5 and 1.3kg and the root mean square error of prediction (RMSEP) were 31.2 and 27.8kg and for Angus-Hereford steers the mean bias were -4.0 and -10.5kg and the RMSEP were 9.14 and 21.5kg for DGM and IGM, respectively. The FM mean bias for Angus steers were -5.61 and -2.93kg and the RMSEP were 12.3 and 13.4kg for CVDS and BeefSpecsDT, respectively. The decomposition for bias, slope, and deviance were 21%, 12%, and 68% and 5%, 4%, and 91% for CVDS and BeefSpecsDT, respectively. The modeling efficiencies were 0.38 and 0.27 and the models were within a 20kg level of tolerance 91% and 88% for CVDS and BeefSpecsDT, respectively. Fat deposition models reported in this review have the potential to assist the beef industry make on-farm management decisions on live cattle before slaughter and improve profitability. Modelers need to continually assess and improve their models but with a caveat of 1) striving to minimize inputs, and 2) choosing on-farm inputs that are readily available.

Effect of SeaFeed, a canola oil infused with Asparagopsis armata, on methane emissions, animal health, performance, and carcass characteristics of Angus feedlot cattle.

The objectives of this project were to measure the effect of SeaFeed, a canola oil infused with Asparagopsis armata, on methane emissions, animal health, performance, and carcass characteristics of feedlot cattle. Angus steers (n = 160) with an initial body weight of 474.4 kgwere fed a steam-flaked wheat and barley ration for 200d in a large, commercial feedlot. A single-blinded randomized complete block design compared two treatments including control and SeaFeed included at a rate of 25mg bromoform per kg dry matter intake (DMI). Monthly testing of bromoform levels in the canola demonstrated that SeaFeed maintained a stable bromoform concentration for 6mo. The inclusion of SeaFeed had no effect on daily DMI. However, steers fed SeaFeed were more efficient with a 6.6% higher (P < 0.01) gain-to-feed ratio as compared to control steers over the 200-d feeding period. This improved efficiency resulted in 0.094kg higher (P < 0.01) average daily gain and 19.7kg higher (P < 0.01) live exit weight in steers fed SeaFeed as compared to control steers. Steers fed SeaFeed produced 51.7% less (P < 0.01) methane and yielded 50.5% less (P < 0.01) methane over the 200-d feeding period as compared to cattle fed the control ration. Peak methane inhibition occurred on day 29 on feed with 90.6% less methane production in cattle fed SeaFeed as compared to control animals. SeaFeed reduced (P < 0.01) methane intensity by 55.4% over the 200-d feeding period. Hot carcass weight tended (P = 0.097) to be 6.9kg heavier in cattle fed SeaFeed as compared to controls. Cattle fed SeaFeed had similar (P > 0.20) marbling, meat color, eye muscle, area, and ultimate pH to control cattle. Interestingly, cattle fed SeaFeed tended (P = 0.054) to have slightly higher fat color scores. Rumen papillae from cattle fed SeaFeed were more (P < 0.01) gray in color and more oval (P < 0.01) in shape as compared to control animals; however, rumen damage was not different between treatment groups. In regards to food safety and residues, all muscle, fat, and kidney samples were free from bromoform residues. Bromine residues in kidney and meat samples were higher (P < 0.01) in the SeaFeed group as compared to controls. Cattle fed SeaFeed produced strip loin steaks similar (P > 0.05) in eating quality to control cattle. These results demonstrate that SeaFeed reduced methane emissions, improved performance, and produced safe beef with similar eating quality to conventional beef.

Methane emissions and rumen microbiome response during compensatory growth on either a forage or grain-based finishing diet in beef cattle.

The aim of this experiment was to evaluate the effect of the level of prior nutritional restriction during backgrounding in Angus steers on methane (CH4) emissions, diet digestibility, rumen fermentation, and ruminal microbiome under either a forage or grain-based finishing diet. Eighty steers (body weight [BW]: 444 ± 39kg, age: 18 ± 1 mo) were blocked and randomly assigned within the block to either an optimal (0.6 to 0.7kg/d) or suboptimal (0.3 to 0.4kg/d) growth rate to exploit compensatory growth (CG), during 97 d of backgrounding. Following, for 84 d, half of the steers in each group were finished on a forage diet while the other half were finished on a grain-based diet. During the backgrounding period, CH4 emissions tended (P ≤ 0.07) to be higher; however, CH4 intensity expressed by BW gain was 50% lower (P < 0.01) for optimal compared to suboptimal growth steers. BW gain, dry matter intake, diet digestibility, and ammonia nitrogen in the rumen were greater (P < 0.01) for optimal compared to suboptimal steers. During the finishing period, CH4 emissions in either forage or grain finishing diets were similar (P > 0.05) for both backgrounding treatments. However, due to greater BW gain in suboptimal steers (1.20 vs. 0.97kg/d), their CH4 intensity-related coefficient decreased (P < 0.05) during the finishing period. Diet digestibility or any fermentation parameter was unaffected (P > 0.05) by previous backgrounding during the finishing period. In fact, rumen microbial abundance measured during finishing was not modified (P > 0.05) by previous backgrounding. Steers finished under grain conditions, had lower (P < 0.01) daily CH4 emissions and CH4 intensity. Additionally, grain-fed steers increased (P < 0.05) BW gain, diet digestibility, propionic, lactic, and valeric acids, Succinivibrionaceae family and Succiniclasticum, Erysipelotrichaceae UCG-002, Sharpea, and Megasphaera bacteria genera, compared to forage-fed steers. In conclusion, ruminal microbiome and fermentation, diet digestibility, and CH4 emissions were unaffected during finishing between prior levels of backgrounding growth. However, given the higher BW gain in suboptimal steers in both finishing diets, CH4 intensity was reduced in comparison to the optimal backgrounded steers. Nevertheless, lifetime emissions of the steers need to be assessed with the different dietary regimens, since suboptimal steers reduced CH4 emissions during the backgrounding period but, additional days of finishing were required to achieve the same BW as their contemporaries.

Influência de suplementos de baixo e médio consumo na fase de crescimento de novilhos mantidos em pastagem tropical e terminados em confinamento

ABSTRACT: The objective was to evaluate the animal production and ingestive behavior of the steers fed different supplements during the growth phase in Aruana grass, and the influence of this supplementation on production performance in feedlot phase. The treatments consisted of three supplements during the growing phase: mineral salt (0.12 g/kg of body weight - BW), low intake energy-protein supplement (1.26 g/kg of BW), and medium intake (3.76 g/kg of BW). Forage canopy characteristics, animal production, and animal behavior on pasture were evaluated in a completely randomized design with three replicates (paddocks). The titanium dioxide marker was used to determine the intake and apparent digestibility during the pasture phase. The production performance in feedlot was evaluated in a completely randomized design with eight replicates (animals). Twenty-four Aberdeen Angus steers (15 ± 1.5 months old; 364.8 ± 21.7 kg BW) were used. At the end of the growth phase the animals were confined and fed a single diet. Dry matter, crude protein, and neutral detergent fiber (NDF) contents of forage and intake were not influenced by the treatments. The average daily gain was higher for the medium intake supplement in pasture phase. The apparent digestibility of NDF (P = and chewing rate were higher for the medium intake supplement. The average daily gain and fat thickness of carcasses were higher for the medium intake supplement in the feedlot phase. The supplements of medium intake increase animal productivity during the growing phase on pastures and cattle’s finishing performance in intensive production systems.

Allostasis as a consequence of high heat load in grain-fed feedlot cattle.

Heat wave intensity, frequency, and duration are increasing in many regions of the world, including locations where highly productive livestock are raised. There are animal health and welfare, as well as economic impacts from these events. In this study, the physiological responses of grain-fed steers during a high heat load challenge through to recovery in climate-controlled rooms (CCR) were intensively evaluated. Two cohorts of 12 Black Angus steers (BW, 615.4 ± 40.1kg) sequentially underwent a simulated heatwave event that consisted of 3 phases in the CCR: PreChallenge (5 d duration and temperature humidity index (THI) range of 65 to 71), Challenge (7-d duration and THI 66 to 95 with diurnal cycling), and Recovery (5 d duration and THI 65 to 70). The Challenge period was modeled on a severe heat wave, characterized by 3 very hot days. Individual rumen temperature (RumT, °C) was collected every 10min, and respiration rate (RR, breaths per minute), panting score (PS), and water usage (L·steer-1·day-1) were obtained at multiple time points daily, by trained observers. Individual animal daily DMI was also determined. Morning (0700 hours) rectal temperature (RecT, °C)was measured on days 3, 5, 7 to 13, 15, and 17. Not unexpectedly, RumT, RecT, RR, and PS rose during Challenge and fell rapidly as conditions eased. Conversely, DMI was reduced during Challenge. During the transition between PreChallenge and Challenge, there were abrupt increases in RumT, and RR. It was also very apparent that during Recovery the steers did not return to the baseline PreChallenge state. Compared to PreChallenge, Recovery was characterized by persistent lowered daily mean RumT (P = 0.0010), RecT (P = 0.0922), RR (P = 0.0257), PS (P ≤ 0.0001), and DMI (P ≤ 0.0001). These results provide evidence that these steers have undergone an allostatic response in response to high heat load, and the new adjusted physiological state post-heat event may not be transient.

Increasing long-chain n-3 fatty acids in beef from forage-finished cattle through supplementation with the calcium salts of fish oil

Two experiments were conducted to determine the effects of dietary fish oil Ca salts supplementation on the muscle deposition of fatty acids, with the major focus on eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) in beef cattle. For Experiment 1, thirty-eight grazing LowLine Angus steers were divided into three groups and supplemented either control, fish oil (FO)- or palm oil (PO)-based fatty acid Ca salts, supplemented individually in dry form. In Experiment 2, 14 Angus heifers and 14 Angus steers were fed free-choice harvested forage and supplemented either PO or FO Ca salts, delivered as a suspension within dried molasses lick tubs. Growth performances, sensory characteristics and the concentrations of EPA and DHA of the M. Longissimus thoracis (LT) were evaluated. M. Longissimus thoracis fatty acid concentrations of EPA and DHA were greater (P&lt;0.001) for cattle fed FO; whereas C18:2 n-6 and the ratio of n-6 to n-3 were greater (P&lt;0.001) for cattle fed PO in both experiments. Sensory evaluation of LT steaks obtained from the carcasses of the LowLine steers of Experiment 1 did not reveal any adverse effects of the FO supplementation (P≥0.2695). We conclude that supplementing FO Ca-salts to forage-fed beef cattle increases muscle deposition of EPA and DHA, with no adverse effects on flavor. Supplementing fish oil to beef cattle is a way to meet the omega fatty acid requirements of humans.

Comparing the responses of grain-fed feedlot cattle under moderate heat load and during subsequent recovery with those of feed-restricted thermoneutral counterparts: blood cells and inflammatory markers

Given the climate projections for livestock rearing regions globally, understanding the inflammatory status of livestock under various heat loads will be informative to animal welfare and management. A survey of plasma inflammatory markers was conducted, and blood leucocyte counts followed to investigate the capacity of the ~ 500 kg grain fed Black Angus steer to respond to and recover from a moderate heat load challenge. Two sequential cohorts of 12 steers were housed in climate-controlled rooms (CCR) for 18 days. A thermally challenged (TC) group (n = 2 × 6) experienced five consecutive periods: PreChallenge, Challenge, and Recovery within the CCR, and 40 days in outdoor pens (PENS and Late PENS). PreChallenge (5 days) and Recovery (7 days) delivered thermoneutral conditions, whereas in Challenge the TC steers experienced a diurnal temperature range of 28–35 °C. A feed-restricted thermoneutral (FRTN) treatment (n = 2 × 6) was run concurrently to differentiate between responses to reduced feed intake alone and moderate heat stress. Blood neutrophil counts were particularly sensitive to moderate heat load with higher numbers during Challlenge and in PENs. The plasma concentrations of TNFα and IL-1β were depressed in the TC group compared to the FRTN counterparts and remained so for 40 days after Challenge. Linear relationships of the concentrations of IL-1β, IL-10, and haptoglobin with rumen temperature or dry matter intake detected in the FRTN group were altered or absent in the TC group. The findings suggest significant impacts of moderate heat load on the inflammatory status of feedlot cattle.

PSVIII-A-8 Growth and Physiological Responses to Heat Stress and Zilpaterol Hydrochloride in Angus and Brahman Steers

Abstract The response to zilpaterol hydrochloride supplementation by two breeds of beef steers under controlled heat stress conditions were evaluated for impacts on growth, carcass merit, and physiological stress indicators. In two separate studies, Brahman and Angus steers were placed in environmental chambers and housed for 21 d under 1 of 2 environmental conditions 1) heat stress (THI = 73 to 85) or thermoneutral (THI = 68). In a 2 x 2 factorial, steers also received 8.38 mg· kg-1· d-1 on 88% DM of zilpaterol hydrochloride (ZH) or soybean meal carrier only for the 21-d period. Feed intake, respiratory rate, and rectal temperatures were evaluated daily. Total weight gain was recorded and used to calculate average daily gain (ADG) and gain-to-feed ratio (G:F). Brahman steers were harvested at the market weight (489.31 ± 97.7 kg) and Angus steers on d ~22 after treatment (307.26 ± 6.23 kg). In both studies, body weight gain and ADG did not differ between environments or supplements. Brahman steers exposed to heat stress exhibited greater (P &amp;lt; 0.05) respiratory rate than thermoneutral steers, regardless of supplement. An environment x day interactions (P &amp;lt; 0.04) was observed for rectal temperature. On d 8, unsupplemented heat-stressed Brahman steers had higher (P &amp;lt; 0.05) rectal temperatures than ZH-supplemented thermoneutral steers. On d 11, ZH-supplemented heat-stressed Brahman steers had higher (P &amp;lt; 0.05) rectal temperatures than unsupplemented thermoneutral steers. Angus steers exposed to heat stress exhibited greater (P &amp;lt; 0.05) respiration rates throughout the experiment than thermoneutral steers. On d 8, unsupplemented heat-stressed Angus steers exhibited greater (P &amp;lt; 0.05) respiration rates than ZH-supplemented heat-stressed steers. On d 8 and 19, heat-stressed Angus steers exhibited greater (P &amp;lt; 0.05) rectal temperatures than thermoneutral steers. Angus steers exhibited an environment x supplement x day interaction (P &amp;lt; 0.05) for rectal temperature, with a decrease (P &amp;lt; 0.05) rectal temperature in ZH-supplemented steers. Carcass merit traits did not differ between environments in Brahman steers. Cold carcass weights were lighter (P &amp;lt; 0.05) in heat-stressed Angus steers compared with thermoneutral steers. ZH-supplemented Angus (but not Brahman) steers exhibited decreased (P &amp;lt; 0.05) respiration rates and rectal temperatures. Together these findings indicate that Brahman steers were more resistant to heat stress than Angus steers but were less efficient, with ~10% less G:F. Based upon the data collected, supplementation with zilpaterol hydrochloride did not negatively impact production in either breed.

PSXIV-26 Live Animal Longissimus Thoracis Mitochondrial Capacities at 10, 13, and 18 Months of Age Are Related to Meat Quality in Angus and Brahman Steers

Abstract Mitochondrial abundance and efficiency correlate with meat color, but relationships between live animal mitochondria and other markers of beef quality remain largely unknown. To test the hypothesis that live animal skeletal muscle mitochondrial markers would be correlated with post-harvest hot carcass weight, ribeye area, calculated yield grade, backfat thickness, and marbling, samples were collected from the longissimus thoracis of Brahman and Angus steers at 10 mo (25 Angus, 23 Brahman), 13 mo (35 Angus, 33 Brahman), and 18 mo (35 Angus, 33 Brahman) of age. Mitochondrial volume density and function were quantified by citrate synthase (CS) and cytochrome c oxidase activities, respectively. Mitochondrial oxidative phosphorylation (OxP) and electron transfer (E) capacities were determined via high-resolution respirometry. Relationships between mitochondrial variables and carcass quality were determined using PROC CORR in SAS (v9.4). Within Angus at 10 mo, integrative (per mg tissue) complex I-supported OxP (PCI), maximal OxP (PCI+II), maximal E (ECI+II), and E supported by complex II (ECII) were positively correlated with hot carcass weight (P ≤ 0.05). Also, within 10 mo Angus, integrative OxPCI and flux control ratio (FCR) for OxPCI were positively correlated with backfat thickness (P ≤ 0.03). Within 10 mo Brahman, integrative PCI was positively correlated with ribeye area (P = 0.04). Within 13 mo Brahman, integrative mitochondrial proton LEAK was positively correlated with hot carcass weight (P = 0.02) and intrinsic (relative to CS activity) LEAK, PCI, and ECI+II were positively correlated with marbling (P ≤ 0.05). Conversely, CS activity was negatively correlated with marbling in 13 mo Brahman (P = 0.05). Integrative, FCR, and intrinsic LEAK were negatively correlated with ribeye area (P ≤ 0.05) but positively correlated with calculated yield grade in 13 mo Angus (P ≤ 0.03). However, at 18 mo, integrative, FCR, and intrinsic LEAK were positively correlated with ribeye area (P ≤ 0.008) but negatively correlated with calculated yield grade (P ≤ 0.01) in Angus steers. Furthermore, integrative and intrinsic OxPCI+II, ECI+II, and ECII were positively correlated with marbling in 18 mo Angus (P ≤ 0.04). Within 18 mo Brahman, CS activity was positively correlated with ribeye area (P = 0.006). Cytochrome c oxidase activity was not correlated with any markers of meat quality. These results suggest that mitochondrial capacity for energy production in Angus and Brahman steers at different life and production stages may dictate potential for skeletal muscle growth and lipid metabolism leading to differences in beef quality at slaughter. This project was supported by USDA NIFA Award #2021-67015-33392.

PSXII-20 Differences in Fat Accretion Rate of Different Depots of Angus, Brahman and Charolais Feedlot Steers

Abstract Understanding accretion rate of intramuscular and subcutaneous fat in feedlot steers is crucial to ensure that carcasses are meeting market specifications and therefore optimizing profitability. Intramuscular fat (marbling) and subcutaneous fat (P8 and rib) are key areas of assessment on the live animals and carcasses determining quality. The objective of the present study was to determine fat accretion rate in three popular breeds of cattle with contrasting accretion rate throughout the feedlotting period. We hypothesized that Angus would have the fastest fat accretion rate being early maturing. Thirty of each Angus, Brahman and Charolais steers were entered into a feedlot (344 ± 5.3 kg initial BW) and six of each breed randomly selected for slaughter at 50-day intervals for 200 days on feed (DOF). Ultrasound scanning and BW were measured at each slaughter point, measuring fat thickness at the rib and P8 site, intramuscular fat (IMF), kidney fat and the eye muscle area (EMA). Body weight, intramuscular fat (%), P8 and rib fat (mm) all had significant interactions between DOF and breed (P &amp;lt; 0.001). At the start of the feeding period, Charolais were lighter than Angus and Brahman (P &amp;gt; 0.001). However, Charolais (663.7 ± 9.31 kg) and Angus were the heavier (680.4 ± 8.68 kg) than Brahman (539.4 ± 8.68 kg) at 200 DOF (P &amp;lt; 0.05). The interaction for P8 and rib fat was due to all breeds having similar fat thickness at 0 DOF (P &amp;gt; 0.05) but Angus had greatest (21.38 ± 0.882 mm, 17.12 ± 0.549 mm), Brahman intermediate (16.73 ± 0.883 mm and 10.38 ± 0.550 mm) and Charolais thinnest (9.97 ± 0.966 mm, 7.23 ± 0.600 mm) P8 and rib fat, respectively, at 200 DOF (P &amp;lt; 0.05). Similarly, IMF was similar between breeds at 0 DOF (P &amp;gt; 0.05), but Angus had greater IMF (7.76 ± 0.287 %; P &amp;lt; 0.001) compared with Brahman (5.08 ± 0.287 %) and Charolais (5.18 ± 0.314 %), which were not different amongst them (P &amp;gt; 0.10). Results of the present study demonstrated the contrasting fat metabolisms of each genotype with Angus steers showing the fastest fat accretion rate for all fat depots, whereas Brahman steers showed intermediate and Charolais slowest subcutaneous fat accretion rate. However, both Brahman and Charolais steers showed similarly low IMF and kidney fat accretion rates. Fat accretion rate of each depot and whole body should be considered in mathematical simulation models of animal growth.

360 Effect of Dietary Protein Levels and Growth Promotants in Dairy-Beef Cross Steers on Nitrogen Utilization Efficiency

Abstract Reducing nitrogen excretion of finishing beef cattle is needed to protect the environment but methods used to decrease nitrogen excretion need to have economic benefits as well. The objective of this experiment was to determine the potential of implant strategy and phase-feeding crude protein (CP) to reduce urinary nitrogen (UN) and fecal nitrogen excretion. Holstein × Angus steers (n = 72) were blocked by body weight (BW) and treatments were randomly assigned to pens (n = 4 per treatment). This experiment was a 2 × 2 factorial design, where cattle were fed a constant CP (control), or the CP content of the diet was reduced every 49 days (phase-fed) and cattle received either an aggressive or moderate implant strategy. All cattle were implanted on d-0 and d-98. Body weight was measured, and blood, urine, and fecal samples were collected on days 0, 49, 98, 147, and at shipping. Phase-feeding CP and implant strategy had no effect (P ≥ 0.47) on dry matter intake or average daily gain. There was a tendency (P = 0.10) for a diet × implant-strategy interaction for feed efficiency, indicating that phase-fed cattle were more efficient with the moderate implant strategy than the aggressive implant strategy. UN excretions decreased (P &amp;lt; 0.01), on day-147 among both implant treatments, indicating that re-implanting on d-98 may have reduced nitrogen excretion. There was a sampling-day × implant interaction (P ≤ 0.03) and a sampling-day × diet interaction (P &amp;lt; 0.01) for blood urea nitrogen concentrations (BUN) and total UN excretion, where BUN and total UN excretion were decreased among the moderate implant and the phase-fed groups on day-147 compared with the aggressive implant and control-fed groups, respectively. Overall, fecal nitrogen concentrations were less for the phase-fed treatment group compared with the control (P ≤ 0.05). These results suggest that phase-feeding CP can be an effective strategy to reduce nitrogen excretion from cattle in the feedlot without negatively affecting performance.

PSVII-28 Effects of Adding Either Fibrolytic Enzymes Or Sodium Butyrate to Feedlot Diets on Rumen Parameters of Angus Cattle

Abstract This study conducted at São Paulo State University feedlot, Dracena campus, Brazil, was designed to evaluate the addition of either sodium butyrate (BUT) or exogenous fibrolytic enzymes (ENZ) on dry matter intake (DMI), ruminal pH, short-chain fatty acids (SCFA), and rumen disappearance rate of Angus cattle. Three Angus steers, cannulated in the rumen (+ 690 kg), were used in a replicated 3 x 3 Latin square, resulting in 6 experimental periods, in a total of 203 days of study. Each experimental period lasted 28 days; 14 days of adaptation diets, and 14 days of the finishing diet containing 85% concentrate (71% finely-ground corn). Cattle were given a 7-day washout interval between periods, where they were allowed to graze. The experimental diets fed to the animals were different only with respect to the feed additives used, according to the treatments: Control (CTL; no feed additives added), ENZ [0.01% of diet dry matter (DM)], and BUT (0.3% and 0.1% of diet DM during adaptation and finishing phases, respectively). The DMI was measured daily, and rumen pH and temperature were measured by data loggers on days 25 and 26 of each experimental period. The rumen fluid samples were collected at 0, 4, 8, and 12 hours after feeding on day 26 of each period to determine the molar proportion of SCFA. The rumen of the animals was emptied on day 27 at 1100 h (3 hours after feeding) and day 28 at 0800 h (before feeding) in each experimental period. The rumen contents were separated into solid and liquid fractions and then weighed. Based on the solid and liquid mass values obtained, as well as the DM intake, the rumen disappearance rate was calculated and expressed in %/h. Data were analyzed by PROC MIXED of SAS (2003), using Tukey's test to compare means when appropriate, considering P ≤ 0.05 as significant. The DMI was not affected (P &amp;gt; 0.76) by treatments in this study. Likewise, no treatment effect was observed on minimum, maximum, and mean ruminal pH (P &amp;gt; 0.23). The pH time below 6.2, 5.6, and 5.2 was not affected by treatments (P &amp;gt; 0.45), as well as pH area under 6.2, 5.6, and 5.2 (P &amp;gt; 0.55). Rumen temperature was lower in cattle fed ENZ when compared with those fed CON and BUT (39.63°C vs. 40.12°C and 40.02°C, respectively; P = 0.04). Furthermore, the molar proportions of SCFA were not affected by treatments (P &amp;gt; 0.71). Cattle consuming ENZ increased ruminal disappearance rate (%/h) when compared with CTL-fed cattle (8.61 vs 6.36; P = 0.05). Thus, the addition of BUT to feedlot diets did not cause any impact on ruminal fermentation parameters; however, the use of ENZ promoted small benefits that deserve further investigation.

369 Effects of Supplementing Sources of Zinc on Digestibility Parameters of Beef Steers

Abstract Zinc (Zn) has numerous functions and many life-sustaining processes depend on the presence of Zn within the body. The objective of this study was to determine if apparent digestibility differed by Zn source. In this study, Angus steers (n = 12, 226 kg ± 16.17) underwent three isozinc treatments: Organic Zn glycinate, Inorganic Zn sulfate (ZnSO4), and Zn hydroxychloride (Phibro Animal Health, Teaneck, NJ). On day 1, steers were weighed, rumen fluid collected, liver biopsy performed, and blood collected. Steers were then placed in metabolism crates for a 4-day adaptation period. Each steer was assigned a source of Zn in a completely randomized design (4 steers/treatment). Steers had ad libitum access to hay and treatments were fed once daily. Treatments contained the assigned source of Zn 0.063 g/d, soybean pellets 0.063 g/d, ground corn 0.063 g/d, and molasses 0.2 g/d. Orts were quantified daily, and total fecal samples were collected and sampled daily at time of feeding (0600h) for 5 consecutive days (d 5 to d 10). On d 10, steers were removed from metabolism crates, weighed, rumen fluid collected, liver biopsy performed, and blood collected. Feed and fecal samples were composited for the entirety of the collection period. Each sample was dried, ground, and analyzed to determine DM, NDF, ADF, fat, protein, and mineral content. Data were analyzed using the proc mixed procedure of SAS. Digestibility results for Organic Zn, Inorganic ZnSO4, and Zn hydroxychloride were DM (70.74, 70.64, 72.46, respectively), NDF (75.98,76.03, 77.79, respectively), ADF (83.00, 82.47, 84.00, respectively), Fat (67.28, 66.00, 70.04, respectively), and protein (69.14, 68.56, 70.12, respectively). Hemicellulose and organic matter (OM) were calculated and determined, with digestibility of Organic Zn, Inorganic ZnSO4, and Zn hydroxychloride to be OM (74.13,73.50, 75.67, respectively), and hemicellulose (57.66, 59.27, 61.65, respectively). The results of proximate analysis reported digestibility of DM, NDF, ADF, fat, protein, OM, and hemicellulose, were not affected (P &amp;lt; 0.05) by treatment. Mineral analysis was performed by Inductively coupled plasma spectroscopy. Treatment did not affect Zinc liver concentrations. However, numerical differences indicate additional research is needed on rumen dynamics to fully understand the impact of mineral source within the animal, and ultimately its final environmental impact.

358 The Effects of Varying Levels of Cotton Gin Byproduct and Wet brewers’ Grains on Growth Performance of Growing and Finishing Steers

Abstract The abundance of craft breweries provides widespread availability of wet brewers grains (WBG) to be used by beef cattle producers as a potential feedstuff. Cotton gin byproduct (CGB) is a feedstuff typically reserved for mature beef cows due to its low and variable feed value. Both WBG and CGB have high cost of transportation but are sometimes used by producers near supply centers due to their low price. The objective of this study was to analyze animal performance of growing Angus steers fed total mixed rations with varying amounts of CGB and WBG. Sixty-four Angus steers (365 ± 26 kg) were allotted and blocked by initial body weight (BW) in a randomized complete block design to 8 dietary treatments and fed in 2 phases, growing phase (GP) and finishing phase (FP) (84-d and 69-d, respectively). Dietary treatments were arranged in a 2 x 4 factorial with two levels of CGB (0 or 25% of DM) and 4 levels of WBG (0, 10, 20 or 30% of DM). The control and base of all treatments were corn, corn silage and soybean meal. Body weights were recorded on two consecutive days at the beginning and end of GP and FP. Feed samples were collected, and refusals were weighed weekly. Data were analyzed using the MIXED procedure of SAS 9.4 with main effects of CGB, WBG, and the interaction. The linear, quadratic, and cubic effects of increasing levels of WBG and CGB were tested with polynomial contrasts. Average daily gain (ADG) did not differ among dietary treatments (0, 25% CGB and 0, 10, 20, 30% WBG) for GP, (1.67, 1.61, and 1.67, 1.57, 1.74, and 1.60 kg/d, respectively) (P &amp;gt; 0.3031), FP (1.53, 1.61 and 1.56, 1.53, 1.61, and 1.58 kg/d) or the overall trial (1.61, 1.62 and 1.62, 1.55, 1.68, and 1.60 kg/d). The addition of CGB increased GP dry matter intake (DMI; 11.06 vs 11.99 kg/d; P = 0.0011), while the addition of WBG linearly decreased GP DMI (11.81, 11.69. 11.81, and 10.81 kg/d; P = 0.0292). There was an interaction between CGB and WBG (P = 0.0206), with increasing levels of WBG at 0% CGB exhibiting a cubic effect (P = 0.0127), but no effect at 25% CGB. Inclusion of CGB decreased feed efficiency (FE) in the GP (6.77 vs. 7.69; P = 0.0008) but had no carry-over effect in the FP. There was no effect of WBG on FE in GP or FP. In conclusion, CGB increased DMI, reduced FE, and maintained ADG. Increasing quantities of WBG did not reduce ADG or FE, but decreased DMI with increasing feeding level. Therefore, WBG and CGB can be considered viable options for cattle producers seeking to lower input costs.

PSVI-27 Evaluation of Coated and Non-Coated Seed Species Pertinent to the Great Basin in Response to in Vitro Ruminal Incubation

Abstract Target grazing has exhibited itself as an effective method of invasive weed mitigation across degraded rangelands in the Great Basin. Additionally, if the seeds of target species are supplemented into the diets of ruminants, they can serve as vectors for the dispersal of native seed species through fecal pats, which may prove to be a useful tactic for rangeland rehabilitation. However, a challenge associated with seed supplementation, is that the seeds of many target species are sufficiently degraded in the rumen. Therefore, the aim of this study was to evaluate the effects of seed coating technologies on germination rates post ruminal in vitro incubation. In vitro incubations were performed on seven species of seeds pertinent to the Great Basin: Achnatherum hymenoides (ACHY), Achillea millefolium (ACMI), Agropyron cristatum (AGCR), Atriplex canascens (ATCA), Elymus elymoides (ELEL), Pseudoregneria spicata (PSSP), and Sphaeralcea grossulariifolia (SPRT) uncoated (control) or coated with either Polyvinylpyrrolidone (PVP) or PVP+ ethocel, as well as uncoated Bromus tectorum (BRTE) seeds. A Daisy II incubator (Ankom Technology, Macedon, NY) was used for the in vitro analysis with rumen inoculum from two rumen-cannulated crossbred Angus steers (body weight = 910.5 ± 34.5 kg) and a buffer ratio of 1:4. Two F57 filter bags containing 1 g of seeds per treatment (control, PVP or PVP+ethocel) were then placed inside of the Daisy II incubator and kept at 39°C for 12 and 24 h for the control treatments, and for 12, 24, and 48 h for the PVP and PVP+ethocel coating treatments. For uncoated seeds, ACHY germination by 24 h was greater when compared with 0 h (P &amp;lt; 0.05), whereas ATCA germination rate decreased linearly by 12 h (P &amp;lt; 0.05). No differences were observed over time on germination rates of BRTE, as well as all of the other uncoated seeds (P &amp;gt; 0.05). When seeds were coated with PVP, ATCA germination rates started to linearly decrease by 12 h (P &amp;lt; 0.05), whereas PVP coated ACMI germination rates only started to decrease by 24 h (P &amp;lt; 0.05). The germination rates of PVP coated ELEL and PSSP seeds only started to significantly decrease by 48 h (P &amp;lt; 0.05). When coated with PVP+ethocel, the observed germination rates were similar to those observed for PVP coated seeds. However, when compared with uncoated seeds, coating with PVP+ethocel seem to decrease germination rates of ACMI and ATCA by 0 h (P &amp;lt; 0.05). No changes on germination rates were observed over time for coated and uncoated AGCR and SPRT (P &amp;gt; 0.05). In conclusion, seed germination rates after in vitro incubation were not increased by coating the seeds with PVP or PVP+ethocel.

348 The Influence of Previous Nitrogen Levels on Nitrogen Metabolism and Rumen Gene Expression of Grain Or Forage-Fed Finished Steers

Abstract The objective of this study was to evaluate how the previous nitrogen levels (PNL) in the diet might affect nitrogen balance and nitrogen-related genes in the rumen of either forage-fed or grain-fed steers during finishing. Twenty-four crossbred Angus steers were randomly distributed into one of two backgrounding nutritional plans: moderate (MP; crude protein (CP): 9.10%) or high (HP; CP:12.6%). After 85 d, animals were blocked by PNL, transitioned, and fed a finishing diet for 105 d, which consisted of either alfalfa only (forage-fed; CP: 21.3%) or predominantly whole grain (grain-fed; CP: 10.8%). Feed, orts, feces, and urine samples were collected in both phases. By the end of the finishing phase, animals were slaughtered, and ventral sac rumen tissue was collected. Gene expression of Aquaporins (AQP) -3 and -7, and UT-B from rumen tissue were assayed via real-time qPCR; 18S rRNA was used as an endogenous control. Animals on MP diets excreted less N through urine (P &amp;lt; 0.01) and feces (P &amp;lt; 0.01), while retaining more N (P &amp;lt; 0.01), which resulted in an increased N efficiency (P &amp;lt; 0.01) compared with HP animals. No differences were observed for microbial N production (P &amp;gt; 0.05). Grain-fed animals consumed less N (P &amp;lt; 0.01), but still had a greater amount of N being digested compared with forage-fed animals (P &amp;lt; 0.01), as well as the least excretion of N through feces (P &amp;lt; 0.01) and urine (P &amp;lt; 0.01), and consequently a greater rate of N being retained (P &amp;lt; 0.01) and a greater efficiency on utilizing the ingested N (P &amp;lt; 0.05). Further, an interaction was also observed between treatment and PNL, where animals coming from a MP had the least dry matter intake, greatest amount of N being digested and least N excretion, fecal output, and excretion of N through the feces (P &amp;lt; 0.05) when finished on a grain-based diet. In the rumen, steers coming from a low PNL that were finished as forage-fed, had the greatest expression of AQP7, with no statistically significant differences observed for the other groups. When comparing only animals backgrounded on MP, AQP7 (P &amp;lt; 0.01) expression was greater in forage-fed animals, with a trend for greater expression of UT-B in grain-fed animals (P &amp;lt; 0.1). Overall, these results indicate that animals receiving MP will reduce their excretion of N while producing the same amount of microbial N due to more efficient N recycling. Further, carried-over effects were also observed after these animals were transitioned to grain-fed finishing systems. In the rumen, PNL affects expression of AQP7 and UT-B, which may ultimately impact nitrogen metabolism, since both genes are also related with urea transport.

PSIV-3 The Effects of Feeding Sprouted Barley on Rumen Health of Backgrounded Steers

Abstract By the year 2050 the world population is expected to reach 9.7 billion, which increases the demand for beef production. Urbanization continues to decrease available cropland, resulting in a need for innovative technologies to produce livestock feed. Controlled environment vertical farming systems are an alternative technology that can be used to produce feed. This research assesses the effects of including sprouted grains grown in this type of system in the ration of backgrounding steers. A total of 60 commercial Angus steers (328.24 ± 6.48 kg) were each stratified into one of four treatment groups (n = 15). A typical ration for the region served as the control and treatment groups had a 5%, 10%, or 20% (DM) inclusion of sprouted barley. Rumen fluid was collected on days 0, 30, and 60 of the trial and analyzed for pH and volatile fatty acids (VFA). Data were analyzed using the PROC MIXED procedure of SAS where day was analyzed as a repeated measure to assess the effects of treatment x day, treatment and day. VFA are presented as a percentage of the total VFA analyzed. There was a treatment x day effect (P = 0.006) on rumen pH where steers getting 5 or 20% sprouted barley had a lower rumen pH at days 30 and 60 than the other two treatment groups. However, it is important to note that all rumen pH values were at healthy levels. Additionally, there was a treatment x day effect (P = 0.01) for total VFA where all values were consistent at days 0 and 30 and then steers receiving 5 or 20% sprouted barley decreased compared with the other two treatments. A treatment x day effect (P = 0.0005) was also observed for acetic acid and demonstrated that on day 30 values decreased from day 0, but steers receiving 5 or 10% sprouted barley decreased most drastically, but at day 60 those receiving 10% sprouted barley was less than the other groups. Propionic acid was also altered by treatmentx day (P = 0.008) such that levels increased from day 0 to day 30 in all groups except those receiving 20% sprouted barley, and then a decrease was observed at day 60 in all treatments with steers receiving 5 or 20% sprouted barley having the least amounts. A treatmentx day effect (P = 0.05) was also seen for butyric acid and is described with an increase from day 0 to day 30 and then a slight decrease at day 60 with those receiving the 10% sprouted barley staying consistent from day 30 to day 60. These data demonstrate that including sprouted barley in the ration of backgrounding cattle has an effect on rumen pH and VFA production in the rumen, but all values stayed within an acceptable range.

PSX-14 Effects of Forage and Grain-Based Finishing Diets on Fatty Acid Profile of Angus Steers Backgrounded Either in a Moderate Or in a High Plane of Nutrition

Abstract The objective of this study was to evaluate the fatty acid profile of beef backgrounded in two planes of nutrition and finished with forage-only or corn. Steers (n = 24) weighing approximately 298.63 ± 10.19 kg were randomly backgrounded in Triticale (100% DM; Moderate n = 12) and alfalfa (85% DM) and beardless wheat (15% DM; High, n = 12), blocked, and finished with forage-only (FORAGE – Alfalfa with 21% CP, 100% DM, n = 12) or with a grain-based diet (GRAIN - Alfalfa with 16% CP, 80% DM and Corn, 20% DM, n = 12). The feeding trial lasted 220 days (85 d backgrounding, 30 d finishing diet adaptation, and 105 d finishing). The fatty acid profile of strip loin steaks (m. longissimus lumborum) was assessed, and data were analyzed as a 2x2 factorial. Overall, no interaction effect between plane of nutrition and finishing diet was observed for individual or group of fatty acids. Minimal effects were observed for plane of nutrition. Steaks from steers backgrounded in Moderate had greater concentrations of C14:1T n-5 (P = 0.04) and C18:1TΔ n-9 (P = 0.04) when compared with steaks from steers backgrounded in High. Beef from steers finished with FORAGE showed higher concentrations of C10:0 (P = 0.01), C14:1T n-5 (P &amp;lt; 0.0001), C15:0 (P = 0.003), C16:0 (P = 0 .001), C16:1T n-7 (P &amp;lt; 0.0001), C17:0 (P = 0.001), C18:0 (P = 0.0002), C18:1TΔ n-9 (P = 0.0003), C18:2T n-6 (P = 0.005), C20:1 n-12 (P &amp;lt; 0.0001), C18:3 n-3 (P = 0.0003), 18:2 CLA t10c12 (P &amp;lt; 0.0001), C22:1 n-9 (P = 0.02), C22:2 n-6 (P = 0.001), and C22:5 n-3 (P = 0.02) when compared with beef from steers fed GRAIN. Beef fed GRAIN, had greater concentrations of C16:1 n-7 (P = 0.001), C18:1 n-9 (P = 0.004), C18:1Δ n-11 (P &amp;lt; 0.0001) and C18:2 n-6 (P = 0.02) when compared with beef fed FORAGE. Overall, backgrounding steers in moderate and high planes of nutrition does not affect the fatty acid profile of beef. Beef fed with FORAGE has higher total Omega 3 (P = 0.05), total Saturated (P &amp;lt; 0.0001), and total Trans fatty acids (P &amp;lt; 0.0001) when compared with beef fed GRAIN. GRAIN-fed beef has total Monounsaturated fatty acids (P = 0.0002) and higher Omega6:Omega3 (P = 0.0003). Regarding health indexes, based on its fatty acid profile, FORAGE-fed beef had Atherogenicity (P = 0.01) and Thrombogenicity indexes (P = 0.0001) when compared with beef fed GRAIN (Table 1).