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Hot-iron branding uses thermal injury to permanently identify cattle causing painful tissue damage. The primary objective was to examine the physiological and behavioral effects of oral meloxicam (MEL), compared to a control, administered at the time of hot-iron branding in Angus and Hereford steers and heifers. The secondary objectives were to investigate breed and sex effects on pain biomarkers. A total of 70 yearlings, consisting of 35 heifers and 35 steers (Angus, Hereford, or Angus × Hereford), were enrolled in the study. Animals were blocked by sex, randomized across weight, and assigned to receive MEL (1 mg/kg) or a placebo (CON). Biomarkers were assessed for 48 h after branding and included infrared thermography (IRT), mechanical nociceptive threshold (MNT), accelerometry and a visual analog scale (VAS), and serum cortisol and prostaglandin E2 metabolites (PGEM). Wound healing was assessed for 12 wk. Hair samples to quantify cortisol levels were taken prior to and 30 d post-branding. Responses were analyzed using repeated measures with calf nested in treatment as a random effect, and treatment, time, treatment by time interaction, breed, and sex as fixed effects. There was a treatment by time interaction for PGEM (P0.01) with MEL having lower values than CON at 6, 24, and 48 h (MEL: 18.34 ± 3.52, 19.61 ± 3.48, and 22.24 ± 3.48 pg/mL, respectively; CON: 32.57 ± 3.58, 37.00 ± 3.52, and 33.07 ± 3.48 pg/mL; P0.01). MEL showed less of a difference in maximum IRT values between the branded (2.27 ± 0.29 °C) and control site (3.15 ± 0.29 °C; P0.01). MEL took fewer lying bouts at 0-12 h (4.91 bouts ± 0.56) compared with CON (6.87 bouts ± 0.55; P0.01). Compared with Hereford calves, Angus calves exhibited greater serum but lower hair cortisol, greater PGEM, more lying bouts, and less healed wound scores at 3, 4, and 5 wk. Compared with heifers, steers exhibited lower PGEM, lower branding site and ocular IRT, higher MNT, and lower plasma meloxicam levels. Steers spent more time lying, took more lying bouts and had greater VAS pain, and more healed wound scores at 5 wk than heifers. Meloxicam administration at branding reduced branding and control site temperature differences and reduced lying bouts for the first 12 h. Breed and sex effects were observed across many biomarkers. Changes from baseline values for IRT, MNT, lying time, step count, VAS pain, and wound scoring all support that branding cattle is painful.Hot-iron branding uses thermal injury to permanently identify cattle causing painful tissue damage. The primary objective was to examine the effects of oral meloxicam (MEL), compared with a control, administered at the time of hot-iron branding in Angus and Hereford steers and heifers. The secondary objectives were to investigate breed and sex effects on pain biomarkers. A total of 70 yearlings, consisting of 35 heifers and 35 steers (Angus, Hereford, or Angus × Hereford), were enrolled. Animals were assigned to receive MEL or a placebo. Changes from baseline values for infrared thermography (IRT), mechanical nociceptive threshold, lying time, step count, visual analog scale score, and wound scoring all support that hot-iron branding cattle is painful and investigation into analgesic strategies is needed. MEL administration reduced IRT differences from the branding and control site and reduced lying bouts. Breed and sex effects were observed across a wide range of biomarkers and should be considered in future pain studies. The practicality of administering a nonsteroidal anti-inflammatory drug once at the time of branding is attractive. However, a multimodal approach using a combination of analgesics or longer acting analgesic option warrants further investigation to alleviate pain and discomfort caused by hot-iron branding.

Cattle are stoic by nature and have long been subject to evolutionary pressure to mask pain to avoid becoming prey. Quantifying pain via biomarkers allows researchers to capture changes that are not easily detected by the human eye. Negative public perception of routine husbandry practices such as dehorning and castration is growing, increasing the need for the development of practices to relieve pain and suffering in cattle. The objective was to quantify pain associated with induced bacterial pneumonia, scoop and hot-iron dehorning, surgical castration, and hot-iron branding, and to investigate analgesic effectiveness. Calves were experimentally inoculated with Mannheimia haemolytica, scoop or cautery dehorned, surgically castrated, or hot-iron branded. Outcome variables were collected at baseline and following husbandry procedures and included serum cortisol; infrared thermography (IRT); mechanical nociceptive threshold (MNT); substance P; kinematic gait analysis; a visual analog scale; chute defense and behavior scoring; clinical illness score; computerized lung score; average activity and rumination; prostaglandin E2 metabolite; plasma serum amyloid A and rectal temperature. Responses were analyzed using repeated measures with calf nested in treatment designated as a random effect, and treatment, time, and their interaction designated as fixed effects. A combination of reduced activity levels, decreased force on calves’ right front limb, and increased visual analog scale pain scores all support that bacterial pneumonia in cattle is painful (P ≤ 0.01). Differences in right front force were observed in calves challenged with M. haemolytica and treated with flunixin transdermal (96.5 kg) and those given a placebo (85.5 kg), indicating that flunixin transdermal may attenuate specific pain biomarkers in cattle with respiratory disease (P < 0.01). Administration of a bupivacaine liposome suspension block at the time of dehorning and castration was as effective at controlling pain as a multi-modal approach of lidocaine and meloxicam (as evidenced by treatment differences in MNT, cortisol and gait analysis (P ≤ 0.04)). Oral meloxicam administration at branding reduced IRT differences from the branding and control site and reduced lying bouts (P < 0.01). Breed and sex effects were observed across a wide range of biomarkers and should be investigated in future pain studies. The need for long-acting analgesic options for cattle that demonstrate pain alleviation across multiple biomarkers is apparent and would be beneficial to alleviating pain from routine husbandry procedures like dehorning, castration, and branding, as well as painful disease conditions such as bovine respiratory disease.

Eighty-three American Wagyu steers (725 ±10.7 kg) were used to evaluate the effects of olive byproduct supplementation on feedlot performance and carcass characteristics. We hypothesized that with supplementation of olive byproduct would improve feedlot performance and longissimus muscle intramuscular fat composition. Steers were blocked by initial body weight (BW) and randomly assigned within block to one of two treatments. Treatments consisted of: 1) Control diet (basal ration with no olive byproduct) + 1 kg of supplemental cracked corn per animal per day, or 2) Control diet + 1 kg of supplemental olive byproduct per animal per day. Steers were housed in feedlot pens (n=4 steers/pen; 11 replicates/treatment) and fed a traditional American Wagyu finishing diet (DM basis: 68.4% DM, 14.3% CP; 74.8% TDN, 1.16 Mcal/kg NEg, 5.3% crude fat). Diets were delivered to pens, once daily, in the morning in amounts to allow ad libitum access to feed over a 24 h period. Olive byproduct and cracked corn were top-dressed to the appropriate treatment pens immediately after delivery of the basal ration. Steers were individually weighed on d -1 and 0, and approximately every 28 d throughout the 177 d experiment. Equal numbers of steers per treatment were slaughtered throughout the experiment and carcass data were collected. Data were analyzed using a mixed effects model of SAS (SAS Inst. Inc.) for a randomized complete block design. Steers receiving olive byproduct had a lower final BW (P < 0.01) when compared to steers receiving the control diet. Longissimus muscle long chain fatty acids C18:1 and C:22:0 were greater (P < 0.05) and C18:0 lesser (P < 0.05) in controls when compared to steers supplemented with olive byproduct. Under the conditions of this experiment, feeding olive byproduct reduced final BW and had minimal impacts on longissimus muscle fatty acid composition.

Twelve steers, fitted with rumen canulae were used in a 4 x 4 Latin square design to examine the impact of the direct fed microbial Propionibacteria acidipropionici (PA) on rumen fermentation characteristics. All steers were housed together in one pen equipped with GrowSafe feed intake monitoring stations and one Greenfeed system used to estimate in vivo methane production. Steers were fed a corn silage-based diet throughout the experiment. Treatments consisted of PA administered at: 1) 0.0; 2) 1.0 x 108; 3)1.0 x 109; and 4) 1.0 x 1010 CFU∙animal-1∙day-1. Treatments were administered directly into the rumen as a single bolus dose daily. On day 7 and 14 of each period, rumen fluid was collected from each steer 2 h post treatment administration for VFA analysis and for determining in vitro fermentation characteristics. Following a 14d washout period, animal treatments were switched, and the experiment repeated. Data were analyzed as a 4 x 4 Latin square design. In vivo propionic acid molar proportions (25.4 vs 23.6±0.24) and total VFA concentrations (125.2 vs 121.3±1.87) were greater (P < 0.05) in steers receiving PA compared with controls. In vitro DM disappearance (P < 0.05; 63.3% vs 59.2%±1.12) and total VFA (P < 0.05; 147.9 vs 145.2±1.76) were greater and methane (ml/g DMD) lesser (P < 0.04; 13.1 vs 15.6±0.11) in fermentation vessels incubated with rumen fluid from animals receiving PA compared with controls. Dry matter disappearance (P < 0.03) and propionic acid (P < 0.04) increased linearly as dose of PA increased. In vitro Total VFA tended (P < 0.08) to increase linearly and methane production tended (P < 0.09) to decrease quadratically in response PA dose. In vivo methane production was similar across treatments. In conclusion, PA addition improved in vivo and in vitro rumen fermentation characteristics.

This study was designed to evaluate the effects of açaí seed (AS) as a fiber source on intake, digestibility, and ruminal fermentation parameters of beef cattle fed a high concentrate diet. Five rumen-fistulated Zebu bulls were used in a 5x5 Latin-square design. Treatments consisted of five diets with different inclusion rates of AS: 0, 5, 10, 15, and 20% of the diet dry matter (DM). The total mixed ration contained 75% of concentrate and 25% of roughage. Mombasa grass silage and AS were used as the roughage sources. The concentrate portion of the diet contained cracked corn (61.8%), soybean meal (8%) and vitamin/mineral premix (5.2% of DM). Each experimental period lasted 25 d and the last 11 d were used for data collection. Total fecal collections were performed over three days. Titanium dioxide was used to estimate the omasal outflow. Statistical significance was declared at P < 0.05, and tendency at 0.05 > P < 0.10. A linear increase was observed for DM (P= 0.07), organic matter (P < 0.05), crude protein (CP, P < 0.05), and neutral detergent fiber (NDF) intake with the inclusion rate of AS. Intake was greatest in bulls receiving diets containing 20% AS. A linear decrease (P< 0.05) in NDF digestibility was detected with the inclusion rate of AS. DM, CP digestibility, and metabolic energy were similar across treatments (P > 0.10). Ruminal and intestinal DM and nutrient digestibility were similar between the treatments (P > 0.10). Rumen concentrations of acetic acid increased (P < 0.05), and total short-chain fatty acids (P = 0.07) and butyrate (P = 0.08) tended to increase linearly with the inclusion of AS. Açaí seed as a source of fiber in confined Zebu bulls diets alters DM intake and rumen fermentation but has no impact on total tract DM digestibility.

Fifty cow-calf pairs were used to investigate the influence of trace mineral (TM) source on reproductive performance following embryo transfer. Cows were blocked by BW and breed and sorted into pens containing 5 cow-calf pairs. Each group was randomly assigned to one of the following treatments: 1) Organic TM (OTM): 75 mg of Cu from Cu proteinate, 8 mg of Co from Co proteinate, 105 mg of Mn from Mn proteinate, 3 mg of Se from Sel-Plex, and 220 mg of Zn from Zn proteinate, animal-1∙d-1; and 2) Inorganic TM (ITM): 255 mg of Cu from Cu sulfate, 2.6 mg of Co from Co carbonate, 1018 mg of Mn from Mn sulfate, 3 mg Se from sodium selenate, and 763 mg of Zn from Zn sulfate, animal-1∙d-1. All cows were fed a roughage-based diet with no supplemental Cu, Co, Mn, Se, or Zn. Cows were individually fed 0.9 kg of the appropriate supplement pellets daily to deliver TM treatments for 89-d, starting 5-d after estrous synchronization. Estrous was synchronized in all cows on d 0 of the experiment and cows received embryos 8-d after expressing estrous. Serum and plasma were obtained every 28-d and analyzed for reproductive hormones and TM, respectively. Data were analyzed as a randomized block design in R (version 4.0.5). Reproductive performance and hormone concentrations were similar across treatments. Cows receiving OTM had greater Se (P < 0.05) and Cu (P < 0.05) concentrations when compared to ITM. There was a treatment x time interaction for Cu concentrations (P < 0.03). Copper concentrations decreased over time in ITM supplemented cows and increased over time in OTM supplemented cows. These data suggest that TM source did not impact reproductive performance but did improve Cu and Se status in cows over the 94-d experiment.

The objective of this experiment was to evaluate the effect of Saccharomyces cerevisiae products (NaturSafe) on in-vitro rumen fermentation characteristics and microbial diversity. Three crossbred feedlot steers fitted with rumen cannulae were adjusted to a moderately high-concentrate diet for 28-d. On d-29, 1 L of rumen fluid was collected from each steer and composited. A set of vaccine bottles (n=5/treatment/time + blanks and controls) containing 0.5 g of basal diet plus dietary treatments were filled with 30 ml of rumen fluid-McDougall’s buffer solution (1:1), sealed, and placed in a 39°C water bath. Treatments consisted of 1) Control (no added NaturSafe); 2) NaturSafe-dry (9 g/animal/day equivalent); 3) NaturSafe-dry (12 g/animal/day equivalent); 4) NaturSafe-liquid (14 g/animal/day equivalent); 5) NaturSafe-liquid (21 g/animal/day equivalent); and NaturSafe-liquid (28 g/animal/day equivalent). Samples were collected at 0, 6 and 12 h post-fermentation. No treatment effect on any fermentation parameters was found at 6 h. At 12-h post-incubation, dry matter digestibility (DMD) (P < 0.04) and molar proportions of propionic acid (P < 0.03) were greater for treatments containing NaturSafe compared with control. Molar proportions of acetic acid (P < 0.07), percent CH4 (P < 0.08), and NH3-N (P < 0.06) tended to be lesser and percent CO2 tended (P < 0.07) to be greater for NaturSafe treatments compared with controls. Microbiome 16S rRNA analysis results suggest that microbial communities differed (P < 0.05) between 6 and 12 h post-incubation. Incorporating NaturSafe into fermentation vessels revealed an inverse correlation with NaturSafe concentration and microbial diversity (P = 0.08) and that the overall microbial diversity was altered (P < 0.03) by NaturSafe concentration. The microbial community was not affected by additive type. These data suggest that NaturSafe alters fermentation characteristics and microbial community diversity toward improved rumen efficiency while reducing environmental impact.

Rumen fluid from three beef steers (480 ± 10 kg), fitted with rumen canulae, were used to investigate the impact of Ca dose and olive meal on in vitro rumen fermentation characteristics. Steers were fed a high concentrate finishing diet for 21d, and rumen fluid was collected from each steer 2h post-feeding. A 2 x 4 factorial arrangement of treatments was used for this experiment. Factors included: 1) 0 or 5% olive meal and 2) Ca dose: 0, 0.02, 0.04, and 0.08% Ca from CaCl2. A McDougall’s buffer-rumen fluid mixture (1:1; 30 mL) was added to conical tubes containing 0.5g of the ground basal diet and incubated at 39°C for 0, 4, 8, and 12h (5 replicates per treatment per time point). After incubation, supernatant was removed for VFA analysis and the remaining digesta was dried to determine DM disappearance (DMD). At 4 and 8h post incubation digestion tubes containing 0.04% Ca had greater (P < 0.001) DMD when compared to all other Ca doses. At 12h post incubation, DMD was greater (P < 0.001) in digestion tubes containing 0.02% and 0.08% Ca compared to all other Ca doses. At 8h post incubation, molar proportions of acetic acid were greater (P < 0.03) in digestion tubes containing olive meal compared to no olive meal and were greater (P < 0.001) in digestion tubes containing 0.08% Ca compared to all other Ca doses. At 12h post incubation, isobutyric acid (P < 0.01) and butyric acid (P < 0.02) were greater in digestion tubes containing 0.02% and 0.04% Ca compared to all other Ca doses. Butyric acid was lesser (P < 0.02) with olive meal inclusion at 12h. Total VFA concentrations were similar across treatments. These data suggest that Ca and olive meal can impact in vitro fermentation characteristics.

The objective of this experiment was to evaluate the effects of Mo source (feed or water) on performance and mineral status of cows and calves fed a forage-based diet for two years (DM basis: 6.6% CP; 0.14% S, 6.7 mg Cu/kg, 2.4 mg Mo/kg). Fifty-four cow-calf pairs were stratified by cow age, BW, and liver Cu and Mo status, and randomly assigned to one of six treatments. Treatments consisted of: 1) Negative control (NC; no supplemental Mo or Cu); 2) Positive control [PC: NC + Cu (3 mg Cu/kg diet DM from CuSO4·5H2O)]; 3) NC + 500 µg Mo/L from MoNa2O4·2H2O in drinking water (Mo 500-water); 4) NC + 1000 µg Mo/L of MoNa2O4·2H2O in drinking water (Mo 1000-water); 5) Mo 1000-water + 3 mg Cu/kg diet DM from CuSO4·5H2O (Mo 1000-water+Cu); and 6) NC + 3 mg Mo/kg diet DM from MoNa2O4·2H2O (3.0 Mo-diet). Cattle were allowed ad-libitum access to feed, water, and a protein supplement throughout the experiment. During the winter months animals were housed in three replicate pens per treatment and during the summer months animals were housed in separate pastures by treatment where cow and calf feed and water intake could be measured separately. Data were analyzed as a completely randomized block design. Throughout the experiment no signs of molybdenosis were observed. There was a treatment x time (P < 0.01) interaction for cow liver Cu concentrations. Cows not receiving supplemental Cu had lower (P < 0.01) liver Cu concentrations than cows receiving supplemental Cu. Cow and calf performance, calf mineral status, cow liver Mo, and plasma and milk Mo and Cu concentrations were similar across treatments. These data indicate that Mo supplemented in water or feed at concentrations used in this experiment had minimal impact on Cu status and overall animal performance.

Shade is a mechanism to reduce heat load providing cattle with an environment supportive of their welfare needs. Although heat stress has been extensively reviewed, researched, and addressed in dairy production systems, it has not been investigated in the same manner in the beef cattle supply chain. Like all animals, beef cattle are susceptible to heat stress if they are unable to dissipate heat during times of elevated ambient temperatures. There are many factors that impact heat stress susceptibility in beef cattle throughout the different supply chain sectors, many of which relate to the production system, that is, availability of shade, microclimate of environment, and nutrition management. The results from studies evaluating the effects of shade on production and welfare are difficult to compare due to variation in structural design, construction materials used, height, shape, and area of shade provided. Additionally, depending on operation location, shade may or may not be beneficial during all times of the year, which can influence the decision to make shade a permanent part of management systems. Shade has been shown to lessen the physiologic response of cattle to heat stress. Shaded cattle exhibit lower respiration rates, body temperatures, and panting scores compared with unshaded cattle in weather that increases the risk of heat stress. Results from studies investigating the provision of shade indicate that cattle seek shade in hot weather. The impact of shade on behavioral patterns is inconsistent in the current body of research, with some studies indicating that shade provision impacts behavior and other studies reporting no difference between shaded and unshaded groups. Analysis of performance and carcass characteristics across feedlot studies demonstrated that shaded cattle had increased ADG, improved feed efficiency, HCW, and dressing percentage when compared with cattle without shade. Despite the documented benefits of shade, current industry statistics, although severely limited in scope, indicate low shade implementation rates in feedlots and data in other supply chain sectors do not exist. Industry guidelines and third-party on-farm certification programs articulate the critical need for protection from extreme weather but are not consistent in providing specific recommendations and requirements. Future efforts should include: updated economic analyses of cost vs. benefit of shade implementation, exploration of producer perspectives and needs relative to shade, consideration of shade impacts in the cow–calf and slaughter plant segments of the supply chain, and integration of indicators of affective (mental) state and preference in research studies to enhance the holistic assessment of cattle welfare.

Eight crossbred steers (BW 719.0 ± 65.0 kg) with ruminal and duodenal cannulae were used to examine the effect of trace mineral (TM) source on digestibility; ruminal and duodenal solubility of Cu, Zn, and Mn; and in vitro release of Cu, Zn, and Mn from the solid fraction of ruminal digesta. Experiment 1 determined the effect of TM source on DM and NDF digestibility in steers fed a corn silage and steam-flaked corn-based diet. Treatments consisted of 10 mg Cu, 20 mg Mn, and 30 mg Zn/kg DM from either sulfate TM (STM) or hydroxy TM (HTM) sources. Following a 14-d adaptation period, total fecal output was collected for 5 d. Dry matter digestibility was not affected by treatment, but NDF digestibility tended (P < 0.09) to be greater in HTM vs. STM supplemented steers. In Exp. 2, steers were fed a diet without supplemental Cu, Zn, or Mn for 19 d. Steers were then administrated a pulse dose of STM or HTM (2× the National Research Council requirements for Cu, Mn, and Zn) via the rumen fistula. Ruminal and duodenal samples were obtained at 2-h intervals starting at −4 and ending at 24 h relative to dosing. Ruminal soluble Cu and Zn concentrations were affected by treatment, time, and treatment × time. Soluble concentrations and percent soluble Cu and Zn in ruminal digesta increased (P < 0.05) above 0-h values for 10 h following dosing with STM, but not HTM. Concentrations of Cu and Zn in ruminal solid digesta were also affected by treatment, time, and treatment × time. Steers dosed with STM had greater (P < 0.05) solid digesta Cu concentrations at 2 and 4 h but lesser (P < 0.05) concentrations from 6 to 20 h post-dosing than those receiving HTM. Ruminal solid digesta Zn concentrations were greater (P < 0.05) in HTM vs. STM-dosed steers from 6 through 24 h post-dosing. Distribution of Mn in ruminal digesta was affected by TM source, but to a lesser extent than Zn and Cu. Duodenal soluble TM concentrations were variable and not affected by treatment. Binding strength of TM to ruminal solid digesta was estimated at 0, 6, and 12 h post-dosing using dialysis against chelating agents. The percentage of Cu and Zn released from ruminal solid digesta by dialysis against Tris–EDTA was greater (P < 0.05) at 12 h post-dosing from steers receiving HTM vs. STM. Results indicate that Cu and Zn from HTM have low solubility in the rumen and appear to be less tightly bound to ruminal solid digesta than Cu and Zn from STM.

Water is the most important nutrient in animal nutrition; however, water intake is rarely measured. The objective of this study was to determine whether previously published water intake (WI) equations for beef cattle would accurately predict WI from four experiments conducted under tropical conditions. The experiments were conducted from 2013 to 2015. Nellore (Bos indicus) growing bulls (Exps. 1, 2, and 3) and heifers (Exp. 4) were used in the feedlot trials. In all experiments, animals were fed for ad libitum DMI. The WI, animal performance, diet composition, and environmental data were collected. The prediction of WI using the current published WI equations was evaluated by regressing predicted and measured WI values. The regression was evaluated using the two-hypothesis test: H0: β0 = 0 and H0: β1 = 1 and Ha: not H0. If both null hypotheses were not rejected, it was concluded that the tested equation accurately estimated WI. To develop a WI prediction equation based on the input variables, a leave-one-out cross-validation method was proposed. The proposed equation was evaluated using similar methodology described above. All previously published eight equations overestimated WI of cattle used in the four experiments conducted in southeast Brazil. A possible explanation for the overestimate of WI is that previously published WI equations were generated from data collected from predominantly Bos taurus cattle raised under temperate climates. From the data collected from experiments conducted with Nellore cattle in southeast Brazil, the proposed equation (WI = 9.449 + 0.190 × MBW + 0.271 × T(MAX) −0.259 × HU + 0.489 × DMI, where the MBW is the metabolic BW (kg(0.75)), T(MAX) is the maximum temperature (°C), HU is the humidity (%) and DMI in kg/d), more accurately to predicts WI of cattle raised under tropical conditions.

Four hundred crossbred steers were used in a randomized complete block design to investigate the effects of supplemental Zn source and concentration, and dietary Cr on performance and carcass characteristics of feedlot steers fed a steam-flaked corn-based finishing diet. Steers were blocked by initial BW within cattle source (3 sources) and randomly assigned within block to 1 of 5 treatments. Before the initiation of the experiment, trace mineral supplement sources were analyzed for Zn and Cr. Zinc and Cr concentrations of the Zn sources were used to balance all dietary treatments to obtain correct Zn and Cr experimental doses. Treatments were the addition of: 1) 90 mg Zn/kg DM from ZnSO4 and 0.25 mg Cr/kg DM from Cr propionate (90ZS+Cr); 2) 30 mg Zn/kg DM from Zn hydroxychloride and 0.25 mg Cr/kg DM from Cr propionate (30ZH+Cr); 3) 90 mg Zn/kg DM from Zn hydroxychloride and 0.25 mg Cr/kg DM from Cr propionate (90ZH+Cr); 4) 60 mg Zn/kg DM from ZnSO4 and 30 mg Zn/kg DM from Zn methionine (90ZSM); and 5) 90 mg Zn/kg DM from Zn hydroxychloride (90ZH). Steers were individually weighed on d-2 and on 2 consecutive days at the end of the experiment. Initial liver biopsies were obtained from all steers at processing. Equal numbers of pen replicates per treatment were slaughtered at a commercial abattoir on day 162, 176, and 211; individual carcass data and final liver samples were collected. Total finishing dietary Zn and Cr concentrations were 118.4, 58.2, 114.2, 123.0, and 108.2 mg Zn/kg DM and 0.740, 0.668, 0.763, 0.767, and 0.461 mg Cr/kg DM, for treatments 1 to 5, respectively. Data were analyzed statistically using preplanned single degree of freedom contrasts. Steers receiving 90ZH+Cr had greater final BW (P < 0.04) and ADG (P < 0.03) when compared with steers receiving 90ZH. Additionally, hot carcass weight was 8.5 kg greater (P < 0.03) for 90ZH+Cr compared with 90ZH supplemented steers. Steers receiving 90ZH+Cr had greater longissimus muscle area when compared with steers receiving 90ZSM. Dry matter intake, G:F, morbidity and mortality, and all other carcass measurements were similar across treatments. These data indicate that under the conditions of this experiment, Zn source and concentration had no impact on live performance, liver Zn and Cu concentrations, and carcass characteristics. Supplemental Cr in diets containing 90 mg of supplemental Zn/kg DM from ZH improved final BW, ADG, and hot carcass weights.

Eighty-nine American Wagyu steers were used to evaluate the effects of dietary barley supplementation on feedlot performance. We hypothesized that barley supplementation would increase ADG compared to non-supplemented control animals. The experimental design was a randomized complete block design. Steers were blocked by initial body weight (BW) and randomly assigned within block to one of two treatments. Treatments consisted of 1) Control (no supplemental barley) and 2) Control diet + 0.9 kg∙animal-1∙d-1 of supplemental barley. Steers were housed in feedlot pens (all pens contained n = 4 steers/pen with the exception of one Control pen that contained n=5 steers; 11 replicates/treatment; experimental unit = pen) and fed a traditional American Wagyu finishing diet (DM basis: 68.42% DM, 14.33% CP; TDN: 74.76%, NEg: 1.16 Mcal/kg, 5.25% EE) for 270d. The basal diet consisted of grass hay, corn silage, cracked corn grain, soybean meal, corn distillers grain, white salt, ground limestone, and olive byproduct. Diets were fed once daily in the morning and barely was top dressed to the appropriate pens, immediately after the basal diet was delivered. Steers were individually weighed on d -1 and 0, and approximately every 28 days throughout the 270d experiment. Data were analyzed using a mixed effects model (PROC MIXED, SAS) for a completely randomized block design. Initial pen BW was used as a covariate in the statistical analysis of all performance data and significance was determined at P ≤ 0.05. Initial and final BW, ADG, DMI, and feed:gain were similar across treatments. Therefore, under the conditions of this experiment, these data suggest that barley supplementation for 270d to American Wagyu cattle did not impact overall animal performance.

The objectives of this study were to quantify the mineral balance of Nellore cattle fed with and without Ca, P, and micromineral (MM) supplementation and to estimate the net and dietary mineral requirement for cattle. Nellore cattle ( = 51; 270.4 ± 36.6 kg initial BW and 8 mo age) were assigned to 1 of 3 groups: reference ( = 5), maintenance ( = 4), and performance ( = 42). The reference group was slaughtered prior to the experiment to estimate initial body composition. The maintenance group was used to collect values of animals at low gain and reduced mineral intake. The performance group was assigned to 1 of 6 treatments: sugarcane as the roughage source with a concentrate supplement composed of soybean meal and soybean hulls with and without Ca, P, and MM supplementation; sugarcane as the roughage source with a concentrate supplement composed of soybean meal and ground corn with and without Ca, P, and MM supplementation; and corn silage as the roughage source with a concentrate supplement composed of soybean meal and ground corn with and without Ca, P, and MM supplementation. Orthogonal contrasts were adopted to compare mineral intake, fecal and urinary excretion, and apparent retention among treatments. Maintenance requirements and true retention coefficients were generated with the aid of linear regression between mineral intake and mineral retention. Mineral composition of the body and gain requirements was assessed using nonlinear regression between body mineral content and mineral intake. Mineral intake and fecal and urinary excretion were measured. Intakes of Ca, P, S, Cu, Zn, Mn, Co, and Fe were reduced in the absence of Ca, P, and MM supplementation ( < 0.05). Fecal excretion of Ca, Cu, Zn, Mn, and Co was also reduced in treatments without supplementation ( < 0.01). Overall, excretion and apparent absorption and retention coefficients were reduced when minerals were not supplied ( < 0.05). The use of the true retention coefficient instead of the true absorption coefficient provided a better estimate of mineral requirements. Dietary mineral requirements were lower for P, Cu, and Zn and greater for Fe compared with previously published recommendations. This study provides useful information about mineral requirements and mineral supplementation to obtain adequate dietary mineral supply of Nellore cattle in tropical conditions.

The objective of the current experiment was to investigate the influence of Cu dose on the relative abundance of Cu trafficking genes in cultured bovine hepatocytes. A liver sample was obtained immediately post-mortem from one healthy Angus steer. Hepatocytes were isolated, counted, and seeded at equal density into 15 separate wells, and incubated for 1 hour in culture media containing: 0.0, 0.10, 1.0, 10.0, or 100 mg Cu/L (3 replicates per Cu dose). Following incubation, cells were collected and total RNA was isolated. Quantitative RT-PCR was used to determine the abundance of transcripts for proteins involved in Cu homeostasis. The identified targets were: ALDH2, APOA1, ATOX1, ATP7A, ATP7B, BHMT, BLVRB, CA2, CCS, COX17, CTR1, ELN, GAPDH, GLUD1, GSS, LOXL1, PDIA3, SOD1, SOD3. β-Actin (ACTB) served as the endogenous control. Significant linear responses existed for ALDH2 (P < 0.001), ATOX1 (P < 0.01), PDIA3 (P < 0.05). As Cu dose increased, the relative abundance of ALDH2 increased, and ATOX1 and PDIA3 decreased. Significant quadratic responses existed for ATP7B (P < 0.001), COX17 (P < 0.05), and SOD1 (P < 0.05). The relative abundance of COX17 was lesser at 0.1 and 1.0 mg Cu/L when compared to 0.0, 10, and 100 mg Cu/L. Transcript abundance for ATP7B and SOD1 was lower at 0, 1, and 100 mg Cu/L when compared to 0.1 and 10 mg Cu/L. These data indicate that certain transcripts are differentially expressed in cultured bovine hepatocytes in response to increasing Cu dose.

Twelve crossbred steers fitted with rumen cannulae were used to determine the influence of trace mineral (TM) source on relative binding strength of minerals in the ruminal insoluble digesta fraction (IDF). Steers (n = 4/treatment) were fed a corn silage-based diet containing no supplemental Cu, Mn, and Zn for 7d. On d 8, steers received a bolus dose (2 x NRC requirement) of the respective TM from sulfate (STM), organic (ORG; provided as Zn methionine, Mn methionine, and Cu lysine), or hydroxy TM (HTM; Micronutrients USA LLC) sources. Ruminal samples were obtained at 2 h intervals starting at -4 and ending at 24 h post dosing. Ruminal samples were centrifuged and supernatant and the IDF were collected and frozen separately. Binding strength of Cu, Mn, and Zn to the IDF was estimated at 0, 12, and 24 h using dialysis against 0.05 M Tris-EDTA. At 0 h pre-dosing, IDF concentrations of Cu, Mn, and Zn were similar across treatments. At 12 h post dosing Cu and Zn IDF concentrations were greater (P < 0.05) in HTM vs. STM and ORG supplemented steers, and Mn concentrations were greater (P < 0.05) in HTM and ORG vs. STM supplemented steers. At 24 h post dosing, IDF Zn concentrations were greater (P < 0.05) in HTM vs STM and ORG supplemented steers and Cu and Mn concentrations were similar across treatments. At 12 and 24 h post dosing the percent Cu and Zn released following dialysis was greater (P < 0.05) in HTM vs STM and ORG supplemented steers. The percent released of Cu, Mn, and Zn at 0 h, and Mn at 12 and 24 h were similar across treatments. Data indicate that a greater concentration of Cu and Zn from HTM is loosely bound to the ruminal IDF.

Two studies were conducted to evaluate the influence of packaging and production system (PS) on retail display life color (L*, a*, and b*), fatty acid profile (% of total fatty acids), lipid oxidation (thiobarbituric acid reactive substances; mg malondialdehyde/kg of muscle), vitamin E content (µg/g of muscle), and odor (trained panelists) during storage of LM. Four (or 3) different packaging treatments were applied to LM from steers fattened on grazing systems (Uruguayan) or on high-concentrate diets (U.S.). From fabrication to application of treatments, Uruguayan LM were vacuum packaged for air shipment and U.S. LM were also vacuum packaged and kept in a cooler until Uruguayan samples arrived. Treatments were applied 7 d after slaughter. In Exp. 1, treatments were vacuum packaging (VP), low-oxygen (O) modified atmosphere packaging (MAP) with nitrogen (N2) and carbon dioxide (MAP/CO), low-O MAP with N2 plus CO and carbon monoxide (MAP/CO), and VP plus an application of peroxyacetic acid (VP/PAA). In Exp. 2 block 1, treatments were VP, MAP/CO, and VP with ethyl-arginate HCl incorporated into the film as an antimicrobial agent (VP/AM). In Exp. 2 block 2, treatments were VP, MAP/CO, MAP/CO, and VP/AM. After 35 d storage, steaks were evaluated during simulated retail display for up to 6 d. In Exp. 1, Uruguayan steaks under MAP/CO had greater ( 0.05) were detected among both VP and MAP/CO in U.S. steaks at this time. No significant ( > 0.05) packaging × PS × time interaction was observed in Exp. 2. Only PS (both experiments) and time (Exp. 1) affected ( 0.05) for any of the fatty acids. Beef from Uruguayan had lower ( < 0.05) SFA and MUFA and greater ( < 0.05) PUFA and n-6 and n-3 fatty acid percentages than U.S. beef. Complexity of fresh meat postmortem chemistry warrants a more comprehensive approach to maximize shelf life.

The objective of this experiment was to investigate the influence of liver Cu concentrations on the relative abundance of liver Cu homeostatic proteins in beef cattle. Archived liver biopsy samples were selected based on Cu concentrations (n = 4 samples 21.7±1.35 mg Cu/kg DM-deficient; and n = 4 samples 73.3 ±10.7 mg Cu/kg DM-adequate). Liver samples were obtained from a subset of multiparous beef cows receiving a forage-based diet with no supplemental Cu (basal diet 6.25 mg Cu/kg DM) or 10 mg Cu/kg DM total diet (Cu supplemented as CuSO4·5H2O) for 99 d. Liver proteins were identified using mass spectrometry, normalized, and relative abundance determined using Scaffold software. A total of 895 identical proteins were identified in each sample and relative abundance of each Cu specific homeostatic protein (n = 13) was recorded. Data were analyzed as a randomized complete block design using R software. Copper homeostatic liver proteins identified were: aldehyde dehydrogenase, apolipoprotein A-1, betaine homocysteine methyltransferase, carbonic anhydrase II, Cu chaperone for superoxide dismutase, Cu transport protein, cytochrome c oxidase Cu chaperone, extracellular superoxide dismutase, flavin reductase, glutamate dehydrogenase, glutathione synthetase, protein disulphide isomerase A3, and Cu-zinc superoxide dismutase. By design, liver Cu concentrations were greater (P < 0.05) in Cu adequate vs. Cu deficient liver samples. Copper deficient liver samples had greater (P < 0.05) relative abundance of glutathione synthetase compared to Cu adequate liver samples. The relative abundance of all other Cu homeostatic liver proteins identified were similar (P > 0.05) across Cu concentrations. These data suggest that deficient and adequate liver Cu concentrations ranging from 16.0 to 109.0 mg Cu/kg DM have minimal impact on the relative abundance of Cu homeostatic proteins in beef cattle. Further investigation is needed to determine if liver Cu concentration influences Cu homeostatic protein function.

Liver abscesses can affect cattle performance, though the impact on well-being is relatively unknown. The purpose of this study was to evaluate the relationship between liver abscess presence and stress-related parameters in feedlot cattle. Three hundred and sixty-three feedlot steers (675 ± 2.3 kg) that were enrolled in a nutrition feeding experiment were allocated to one of three groups based on the liver abscess score assigned after slaughter. The liver abscess scoring groups were: no liver abscess presence (NLA; n = 316); mild liver abscess presence (MLA; n = 21) and severe liver abscess presence (SLA; n = 24). Two animals were unable to be assigned liver abscess scores. Two days prior to slaughter, at the time of weighing, hair samples were collected from the right rump of each animal and analyzed for cortisol concentrations. Additionally, during restraint, infrared thermography was used to quantify eye temperatures and a mobility score was assigned to each animal upon chute exit. During slaughter, exsanguination blood was collected from 115 of the 363 animals and analyzed for serum cortisol concentrations. Cattle were blocked by nutrition feeding treatments and data were analyzed using analyses of variance to determine differences in outcome variables between liver abscess score groups. All animals were included in the infrared analysis and 115 animals were included in the serum and hair cortisol analyses. Infrared thermography (P = 0.55), hair cortisol (P = 0.96), and serum cortisol (P = 0.21) were similar across all liver abscess scores. All animals exhibited normal mobility, thus these values were not included in the analysis. The data indicate that under the conditions of this experiment, liver abscesses did not impact measured stress-related outcomes. Additional research is necessary to understand the impact of liver abscess presence on other stress-related parameters associated with well-being in cattle.

The objective of this experiment was to evaluate the influence of beef cattle breed, nutritional treatment, and finishing strategy (pasture vs. feedlot) on the relative abundance of mRNA associated with lipid metabolism in longissimus muscle (LM). Eighty-three uncastrated males from three genetic groups: Nellore (N), ½ Angus x ½ Nellore (A) and ½ Senepol x ½ Nellore (S), were randomly assigned to dietary treatments supplied during the growing phase. Treatments consisted of mineral supplement or concentrate supplement (0.3% BW). Following the growing phase, two replicates within each treatment x breed group were randomly assigned to one of two finishing systems (Figure 1): Pasture grazing + concentrate (PC) and Conventional feedlot (CF), both are supplemented at 2% BW/had/d (Table 1). After 209 days the animals were slaughtered, an LM sample (5.0g) was removed between 12th and 13th ribs from each animal and frozen (liquid nitrogen). The relative abundance of mRNA associated with lipid metabolism was measured by qRT-PCR. Target genes include PPARα, PPARγ, SREBP1c, SCD1, LPL, FBP4, CPT2, ACOX and ACCα. The ∆∆ Ct was used to calculate the data and analyzed using the mixed procedures of SAS for a 3×2×2 factorial arrangement of treatments. Mineral supplementation during the growing phase increased (P < 0.05) the relative abundance of mRNA of PPARα and PPARγ compared to concentrate. The relative abundance of PPARγ, SREBP1c, SCD1, FABP4, ACOX, was greater (P < 0.05) in CF compared to PC. Angus LM muscle showed greater (P < 0.05) relative abundance of SREPB1c compared to Nellore and Senepol. The muscle of Nellore and Angus had greater (P < 0.05) relative abundance of PPARα SCD1 and lower (P < 0.05) of PPARγ when compared to Senepol breed. Therefore, in this study, the conventional feedlot and Angus are more positively associated with differential expression of adipogenic genes.

Four hundred and thirty-two beef steers (346.3 ± 63.7 kg BW) were used to determine the effects of Zn source on feedlot cattle fed ractopamine hydrochloride. Cattle were blocked in groups of 54 by BW and housed in 48 pens containing 9 steers per pen. Pens within a weight block were randomly assigned to treatments in a 2 x 3 factorial arrangement, with factors being: 1) 0 or 30.1 mg of ractopamine HCl/kg DM fed during the final 29 days on feed; and 2) Zn source: 90 mg of supplemental Zn/kg DM from ZnSO4; Zn sulfate (67%) + Zn methionine (33%); and Zn from Zn hydroxychloride, fed through the entire feeding period. Cattle were fed a high concentrate finishing diet for 154 d and slaughtered at a commercial abattoir. Average daily gain, DMI, feed efficiency and carcass characteristics were determined after slaughter. Zinc source had no impact on live animal performance. Cattle fed ractopamine HCl had greater (P < 0.01) final BW, greater (P < 0.001) ADG, improved (P < 0.001) G:F, heavier (P < 0.01) HCW, and larger (P < 0.05) longissimus muscle compared to non-ractopamine supplemented steers. There was a Zn source by ractopamine interaction (P < 0.01) for dressing percentage. Cattle receiving ractopamine HCl with Zn hydroxychloride had a greater dressing percentage (P < 0.05) when compared to ractopamine HCl cattle fed other Zn sources. Cattle receiving ractopamine HCl with Zn sulfate had a lesser dressing percentage (P < 0.05) when compared to ractopamine HCl cattle fed other Zn sources. Additional Zn source by ractopamine HCl interactions were not significant. These data indicate that Zn source has minimal impacts on feedlot steer performance and carcass characteristics when supplemented to cattle receiving 0.0 or 30.1 mg of ractopamine HCl/kg DM.

Four hundred and thirty-three Angus and Angus cross-bred steers (Body Weight 344 ± 13.3 kg) were utilized in this experiment to compare different varieties of grain corn and α-amylase enzyme on feedlot cattle performance and carcass characteristics. Steers were blocked by body weight and breed and randomly assigned to treatments. Treatments consisted of: 1) Commercial commodity corn (CON); 2) Experimental test corn (TEST;), 3) 50:50 blend of CON and TEST corn sources (BLEND), and 4) CON with 5g of α-amylase enzyme added/hd/d (AMZ; Amaize®, Alltech). Steers were slaughtered after 138 days on feed. Feedlot performance, net energy recovery, hot carcass weight, dressing percentage, subcutaneous adipose tissue depth, longissimus muscle area, marbling score, and calculated yield grade data were analyzed as a randomized complete block design using PROC MIXED of SAS. Dietary treatment had no effect (P > 0.20) on BW, average daily gain, feed efficiency, or net energy recoveries. There was a tendency for daily dry matter intake (DMI) to be influenced by treatment: d 0 – d 90 (P < 0.09), d 91 – slaughter (P = 0.11), and d 0 – slaughter (P < 0.08). Dry matter intake was consistently greater for steers receiving the AMZ treatment when compared to all other treatments. Daily DMI for the TEST treatment was consistently lower than DMI for all other treatments. Hot carcass weight (P = 0.56), dressing percentage (P = 0.10), 12th subcutaneous fat depth (P = 0.88), longissimus muscle area (P = 0.84), yield grade (P = 0.91), marbling score (P = 0.76), quality grade (P = 0.67), and the distribution of USDA yield and quality grades (P > 0.74) were similar across treatments. These results indicate the value of the TEST corn as an energy source in feedlot cattle diets is similar to the value of COM corn an energy source.

Twelve Angus steers (BW 452.8 ±21.8 kg) fitted with ruminal cannulae were used to determine the impact of trace mineral source on neutral detergent fiber (NDF) digestibility, short chain fatty acid (SCFA) production, and ruminal solubility of Cu, Mn, and Zn. Steers were fed a low-quality grass hay diet (10.8% CP, 63.1% NDF, 6.9 mg Cu/kg, 65.5 mg Mn/kg, and 39.4 mg Zn/kg) supplemented with protein for 21 d. Treatments consisted of 20, 40, and 60 mg supplemental Cu, Mn, and Zn/kg DM, respectively from either sulfate (STM) or hydroxy (HTM) sources (n = 6 steers/treatment). Following a 21-d adaptation period total fecal output was collected for 5 d. Dry matter digestibility tended (P < 0.07) to be reduced (51.9 vs. 53.4 ±0.52%) and NDF digestibility was reduced (P < 0.04; 40.4 vs. 42.7 ±0.67%) in STM vs. HTM steers. On d 6, rumen fluid was collected at 0, 2, and 4h post feeding. Steers receiving HTM had lesser (P < 0.02) butyric acid and greater (P < 0.05) total SCFA than STM steers. Steers were then fed the same grass hay diet without supplemental Cu, Zn, or Mn for 14 d. On d 15 steers received a pulse dose of 20, 40, and 60 mg Cu, Mn, and Zn/kg DM, respectively from either STM or HTM. Ruminal samples were obtained at 2h intervals starting at -4 and ending at 24h relative to dosing. Ruminal soluble mineral concentrations were greater (P < 0.05) for Cu at 4, 6, 8, 10, 12, and 14h; for Mn at 4 and 6h; and for Zn at 4, 6, and 8h post dosing in STM compared to HTM steers. Results indicate that ruminal solubility of Cu, Mn, and Zn differs between STM and HTM sources and rumen Cu, Mn, and Zn solubility may impact ruminal fermentation.

Two experiments evaluated the effects of band castration and oral administration of an anal- gesic in association with castration on performance and behavioral and physiological responses in yearling beef bulls. In Exp. 1 Angus and Charolais-crossbred bull calves (n = 127; 309.8 ± 59.04 kg BW) and in Exp. 2 Hereford, Angus, and Hereford × Angus crossbred bulls (n = 30; 300.8 ± 4.96 kg BW) were stratified by BW and randomly assigned to 1 of 3 treatments: 1) band castration (BAND), 2) band castration with oral administration of meloxicam (BAND-MEL), and 3) sham castration (SHAM). The BAND and SHAM pro- cedures were completed on d 0. The SHAM treatment consisted of all animal manipulations associated with band castration without band application. Meloxicam was administered on d -1, 0, and 1 (1.0, 0.5, and 0.5 mg/kg, respectively) via an oral bolus. Body weight and a subjective chute score (CS) were collected on d -1, 0, 1, 7, 14, and 21 (d 28 Exp. 1 only). In Exp. 2, jugu- lar blood samples were collected immediately before castration and 24 h postcastration for substance P (SP) analysis. In Exp. 2, video documentation on d 0 was used to determine range of vertical head motion (DIST) on a subset of animals during treatment administra- tion. In both experiments, ADG was similar (P ≥ 0.50) between BAND and BAND-MEL, but ADG in SHAM cattle was greater (P < 0.001) and tended (P = 0.07) to be greater than castrates in Exp. 1 and 2, respectively. In Exp. 1, CS did not differ (P ≥ 0.26) between BAND and BAND-MEL on any day, but castrates exhibited less desirable CS on d 1 and 28 than SHAM cattle. In Exp. 2, CS was not affected (P ≥ 0.41) by castration or the presence of meloxicam. In Exp. 2, DIST did not differ (P = 0.57) between BAND and BAND-MEL, but when pooled, castrates exhibited greater (P = 0.04) DIST than SHAM. In Exp. 2, plasma SP concentrations were simi- lar between BAND and BAND-MEL (P = 0.81) and between castrates vs. sham cattle (P = 0.67). Results indicate no impact of meloxicam administration on per- formance or behavioral and physiological responses to band castration. However, there was a negative impact of castration on ADG and DIST.

Observations were collected for the purpose of comparing exit velocity measurements in the form of exit score (ES; walk, trot, canter, or run) and flight speed (FS) as assessments of cattle temperament. Squeeze chute exit velocity was obtained for 1,181 crossbred yearling steers using ES and FS temperament systems. Flight speed used infrared sensors to determine the time taken for an animal to traverse a fixed distance of 1.83 m after exiting the squeeze chute. Exit score (1=walk, 2=trot, 3=canter, and 4=run) was assigned by 2 different observers when each steer crossed a fixed point between the infrared sensors. All animals were scored with each system (ES and FS) simultaneously on exiting the squeeze chute on d -21 and d -1 of the experiment. Of the 1,181 cattle, 357 were moved to a nearby research feedyard for use in a 140 d feedlot trial. These cattle were scored using both measurement systems and BW was recorded at 35 d intervals throughout the trial. Exit score was assessed for observer reliability, ES and FS were compared for measurement repeatability, and both were assessed on ability to predict ADG. Exit score between observers on a single day showed considerable agreement (weighted Kappa=0.66), indicating the system was reliable between different observers. However, the agreement for a single observer between day was only moderate (weighted Kappa=0.40), indicating a day effect for ES. In addition, although mean velocities for day were not different (P>0.18; FS=2.98±.87 and 3.02±0.87 m/s for day, respectively), the persistence of FS for each animal was low (Spearman rank correlation coefficient=0.25). The frequency that an animal would be placed into the same third of FS or receive the same ES on consecutive weigh days was 50% and 60.0%, respectively, and both were moderate predictors of ADG (R2=0.14 and R2=0.17). These data indicate that ES and FS are reliable instruments for assessment of temperament on a given day, and show moderate repeatability across days. Exit score and FS show similar ability to predict ADG and can be used interchangeably as measures of temperament.

The objective of this study was to examine the effects of different sources of dietary omega-3 (n-3) fatty acid supplementation on plasma, red blood cell, and skeletal muscle fatty acid compositions in horses. Twenty-one mares were blocked by age, BW, and BCS and assigned to 1 of 3 dietary treatments with 7 mares per treatment. Dietary treatments were: 1) control or no fatty acid supplement (CON), 2) 38 g of n-3 long chain, highly unsaturated fatty acid (LCHUFA) supplement/d provided by algae and fish oil (MARINE) containing alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA), and 3) 38 g of n-3 LCHUFA supplement/d provided by a flaxseed meal (FLAX) containing ALA. Each supplement was added to a basal diet consisting of hay and barley and was fed for 90 d. Blood samples and muscle middle gluteal biopsies were taken at d 0, 30, 60 and 90 of supplementation. Plasma, red blood cell and skeletal muscle fatty acid profiles were determined via gas chromatography. Plasma linoleic acid (LA) and ALA were at least 10 and 60% less (P < 0.01), respectively, in the MARINE compared with the FLAX and CON groups. Plasma EPA and DHA were only detected in the MARINE group, and EPA increased 40% (P < 0.001) from d 30 to 60, and DHA 19% (P < 0.01) from d 30 to 90. Red blood cell LA and ALA were not different among treatments. Red blood cell EPA and DHA were only detected in the MARINE group, where EPA increased 38% (P < 0.01) from d 30 to 60, and DHA increased 56% (P < 0.001) between d 30 and 90. Skeletal muscle LA was at least 17% less (P < 0.001) in the MARINE group compared with the other treatments. Skeletal muscle ALA was 15% less (P = 0.03) in the MARINE group compared with FLAX and CON groups. Skeletal muscle EPA was at least 25% greater (P < 0.001) in MARINE group compared with other treatments and increased (P < 0.001) by 71% from d 30 to 60. Skeletal muscle DHA was at least 57% greater (P < 0.001) in the MARINE group compared with other groups and increased (P < 0.001) by 40% between d 30 and 90. As far as the authors are aware, this is the first study to demonstrate that dietary fatty acid supplementation will affect muscle fatty acid composition in horses. Incorporation of n-3 LCHUFA into blood and muscle depends directly on dietary supply of specific fatty acids.

Thirty-three colostrum-deprived Holstein bull calves (initial BW of 131 ± 4 kg) were used to determine the effect of timing of anthelmintic administration relative to vaccination on antibody titer response to vaccine component antigens. When calves were at least 3 mo of age, they were sorted randomly into individual pens and assigned to 1 of 3 treatment groups, treatments consisted of 1) dewormed 2 wk before vaccination (DPV), 2) dewormed at the time of vaccination (DV), or 3) control, vaccinated but not dewormed (CONT). All calves were inoculated with infective larvae of brown stomach worms (Ostertagia ostertagi) and intestinal worms (Cooperia spp.) on d 1, 7, 10, 14, and 18 for a total dose of 235,710 infective larvae per calf. Calves (DPV and DV) were dewormed on d 21 or 35 with a 10% fenbendazole suspension at 5 mg/kg of BW. On d 35, all calves were vaccinated with a modified-live virus respiratory vaccine containing IBRV (infectious bovine rhinotracheitis virus), BVDV-1 (bovine viral diarrhea virus genotype 1), BVDV-2 (BVDV genotype 2), PI-3 (parainfluenza-3), and BRSV (bovine respiratory syncytial virus). During the 103-d experiment, weekly fecal egg counts, blood, and rectal temperatures were collected and health status was recorded daily. Blood samples were obtained weekly to determine serum neutralizing (SN) antibody titers to IBRV, BVDV-1, BVDV-2, and PI-3 and cytokine levels for IL-4, IL-6, TNF-α (tumor necrosis factor-α), and IFN-γ (interferon-gamma). There was a tendency (P < 0.09) for CONT calves to have greater IL-4 concentrations. By design, control calves had greater (P < 0.01) fecal egg counts during the experiment. All calves developed antibody titers to IBRV, BVDV-1, BVDV-2, and PI-3 by d 15 postvaccination. On d 88, all calves were challenged with IBRV and blood samples were obtained on d 88, 89, 90, 93, 95, 98, 99, and 103. All calves had increased rectal temperatures during the final 7 d of the IBRV challenge. However, the CONT group had greater (P < 0.01) rectal temperatures on each sampling day except d 90 compared with the DPV and DV treatments. Therefore, deworming before or at vaccination reduced parasite burden and decreased rectal temperature increase after an IBRV challenge. Deworming strategy had no effect on antibody response to vaccination or IBRV challenge.

The objective of this study was to determine the optimal postmortem aging period and nutrient composition for Beef Value Cuts of the round. Forty USDA Select and 40 Premium USDA Choice beef carcasses were selected from a commercial beef packing plant in Colorado over a 12-wk period. The bottom and inside rounds were collected from both sides of each carcass for further fabrication into the following muscles: adductor, gastrocnemius, gracilis, pectineus, and superficial digital flexor. Each pair of muscles was cut into 7 steaks and randomly assigned to 1 of the following aging periods: 2, 4, 6, 10, 14, 21, and 28 d, and placed in refrigerated storage (2°C, never frozen). Upon completion of the designated aging period, steaks were removed from storage, cooked to a peak internal temperature of 72°C, and evaluated using Warner-Bratzler shear force (WBSF). A 2-way interaction was detected (P0.05) between individual muscle and postmortem aging period. The WBSF of all muscles except the superficial digital flexor decreased with increased time of postmortem aging. Quality grade did not affect (P0.05) WBSF values for the adductor, gastrocnemius, pectineus, and superficial digital flexor muscles. Exponential decay models were used to predict the change in WBSF from 2 to 28 d postmortem (aging response). The adductor, gastrocnemius, Select gracilis, Premium Choice gracilis, and pectineus required 21, 14, 23, 23, and 25 d, respectively, to complete the majority of the aging response. To determine the nutrient composition of the adductor, gastrocnemius, gracilis, pectineus, semimembranosus, and superficial digital flexor, bottom and inside rounds were collected from 10 USDA Select and 10 Premium USDA Choice carcasses and fabricated into the respective muscles, cut into 2.54-cm cubes, frozen (-20°C), and then homogenized. The adductor, gracilis, pectineus, semimembranosus, and superficial digital flexor were analyzed for DM, moisture, CP, and ash percentages. All muscles were evaluated for total lipid, fatty acid, and cholesterol composition. When quality grades were combined, all muscles fell into the extra lean or lean categories specified by USDA guidelines. Results of this study illustrate the potential for Beef Value Cuts of the round to be sold in food service operations and retail stores with marketing emphasis being placed on the exceptional leanness and acceptable tenderness of these cuts.

The objective of this experiment was to determine if dietary inclusion of fish meal would increase plasma and luteal tissue concentrations of eicosapentaenoic and docosahexaenoic acids. Seventeen nonlactating Angus cows (2 to 8 yr of age) were housed in individual pens and fed a corn silage-based diet for approximately 60 d. Diets were supplemented with fish meal at 5% DMI (a rich source of eicosapentaenoic acid and docosahexaenoic acid; n = 9 cows) or corn gluten meal at 6% DMI (n = 8 cows). Body weights and jugular blood samples were collected immediately before the initiation of supplementation and every 7 d thereafter for 56 d to monitor plasma n-3 fatty acid composition and BW. Estrous cycles were synchronized using 2 injections of PGF(2α) administered at 14-d intervals. The ovary bearing the corpus luteum was surgically removed at midcycle (between d 10 and 12) after estrus synchronization, which corresponded to approximately d 60 of supplementation. The ovary was transported to the laboratory, and approximately 1.5 g of luteal tissue was stored at -80°C until analyzed for n-3 fatty acid content. Initial and ending BW did not differ (P > 0.10) between cows supplemented with fish meal and those with corn gluten meal. Plasma eicosapentaenoic acid was greater (P < 0.05) beginning at d 7 of supplementation and docosahexaenoic was greater (P < 0.05) beginning at d 14 of supplementation for cows receiving fish meal. Luteal tissue collected from fish meal-supplemented cows had greater (P < 0.05) luteal n-3 fatty acids and reduced (P < 0.05) arachidonic acid and n-6 to n-3 ratio as compared with tissue obtained from cows supplemented with corn gluten meal. Our data show that fish meal supplementation increases luteal n-3 fatty acid content and reduces available arachidonic acid content, the precursor for PGF(2α). The increase in luteal n-3 fatty acids may reduce PGF(2α) intraluteal synthesis after breeding resulting in increased fertility in cattle.

Effects of genotype (GEN) and implant program (IMP) on LM and gluteus muscle (GM) tenderization were investigated using crossbred steer (n = 185) and heifer (n = 158) calves. The 3-marker GeneSTAR Tenderness panel [CAST (calpastatin), CAPN1 316 (µ-calpain), and CAPN1 4751 (µ-calpain)] was used to determine the GEN of each animal (reported as total number of favorable alleles, 0 through 6). Calves were randomly assigned to 1 of 2 IMP, conventional (CNV) or delayed. Cattle in the CNV group were implanted at the beginning of the finishing period with Revalor-IS or Revalor-IH (Intervet Inc., Millsboro, DE), and then reimplanted 59 d later with Revalor-S or Revalor-H (Intervet Inc.). Calves in the delayed group received a single terminal implant (Revalor-S or Revalor-H) administered 45 d after initiation of the finishing period. Warner-Bratzler shear force (WBSF) was measured on LM and GM steaks at 3, 7, 14, 21, and 28 d postmortem. No interactions between the main effects of sex, IMP, or GEN were detected (P > 0.05) for WBSF. An IMP × postmortem aging (age) interaction was detected (P < 0.05) for LM and GM WBSF. For both muscles, steaks from CNV cattle had WBSF values that were approximately 0.2 kg greater (P < 0.05) than the values for steaks from delayed animals, but only during the early postmortem period (3 to 7 d). A linear effect of GEN on WBSF was detected (P < 0.05) for LM and GM steaks. Within each muscle, steaks from cattle with 6 favorable alleles had WBSF values 0.33 kg less than the values for steaks from cattle with 1 favorable allele. The GEN × age interaction was not significant for LM (P = 0.14) or GM (P = 0.20), but a numerical trend was observed for the effect of GEN on WBSF to diminish as age increased. To investigate how genetic markers could be interfaced with current beef carcass quality grading, cattle were sorted into 2 gene marker groups (GMG), ≤3 vs. ≥4 favorable alleles. For both muscles, GMG was effective only at identifying tenderness differences within the Select grade. When aged ≤14 d, Select LM steaks from cattle with ≥4 alleles had smaller (P < 0.05) WBSF values than did LM steaks from animals with ≤3 alleles. Preslaughter factors (sex, IMP, and GMG) controlled in the present study each accounted for less than 7% of the explained variation in tenderness of the test population. Results from this study suggest that the 3 GeneSTAR Tenderness markers were associated with small differences (0.33 kg) in WBSF and may be useful for increasing the consistency of Select beef, but these specific markers accounted for only a minor amount of variation in beef tenderness.

Results from experiments investigating Cu metabolism in ruminants indicate that Cu is involved in lipid metabolism. Copper supplementation ranging from 10 to 40 mg of Cu/kg of DM to high-concentrate finishing diets decreased subcutaneous adipose tissue deposition and decreased cholesterol concentrations but increased unsaturated fatty acid composition of LM. Serum norepinephrine tended to be greater in Cu-supplemented steers after a 24-h feed withdrawal and at 2 h postfeed consumption, potentially explaining the reduction in subcutaneous adipose tissue deposition. However, when exogenous norepinephrine was administrated, serum NEFA concentrations were less in Cu-supplemented steers, possibly due to the nonsupplemented control steers having a greater subcutaneous adipose tissue depth at slaughter relative to Cu-supplemented steers. Furthermore, in vitro basal and epinephrine-stimulated lipolytic rates of subcutaneous adipose tissue were greater in Cu-supplemented steers relative to controls. These data indicate that that Cu may influence lipogenic or lipolytic function in subcutaneous adipose tissue. In an attempt to further investigate the effect of Cu on lipid metabolism, lipogenic, lipolytic, and homeostatic mechanisms related to Cu are currently being studied. Recent data indicate that genes involved in bovine liver Cu homeostasis are correlated with Cu transporter protein gene expression in the bovine liver. Therefore, the overall intent of this review is to discuss possible mechanisms whereby Cu may affect lipid metabolism in ruminants.

A 4 × 2 factorial arrangement of treatments (4 growth-enhancement treatments × 2 sex classes) was used to quantify effects of initial implanting (I-implant, d 0), terminal implanting (T-implant, d 63), and feeding ractopamine hydrochloride [RAC, 200 mg/(animal/d)] for the last 28 d on feed on carcass characteristics and LM shear force (WBSF) of calf-fed steers (n = 159) and heifers (n = 132). Growth-enhancement treatments included the following: TRT1, T-implant only; TRT2, I-implant and RAC; TRT3, I-implant and T-implant; TRT4, I-implant, T-implant, and RAC. Growth responses (BW and ADG) were measured in 3 segments of the finishing period: 1) d 0 to 63, 2) d 63 to 28 d before slaughter, and 3) final 28 d. Cattle were slaughtered after 152, 166, or 180 d of finishing; carcass data were collected after a 48-h chill; and LM WBSF was measured at 3, 7, 14, 21, and 28 d postmortem. A priori contrasts were constructed to test effects associated with use vs. exclusion of growth enhancement in each segment of the finishing period. The interaction between sex class and treatment was not significant (P > 0.05) for any trait tested, indicating that the 4 treatments elicited similar effects in both sexes. Initial implanting improved (P 0.05) by initial or terminal implanting; however, RAC supplementation increased (P = 0.007) mean LM WBSF by 0.23 kg, which translated into a reduction (P = 0.007) in predicted consumer acceptance of LM steaks.

Excess nitrogen excretion is viewed as a worldwide environmental problem, and blood urea nitrogen (BUN; mg/dl) has been shown to be a predictor of nitrogen excretion in cattle. As a result, the objective of this study was to identify factors influencing BUN in a cohort of Angus cattle. Steers (n = 98) were born between February and June of 2016 and entered Colorado State University’s Feed Intake Unit (FIU) in May 2017 at an average age of 394.6 ± 21.0 d. While in the FIU, steers were fed a growing diet consisting primarily of corn silage and alfalfa hay. Animals were subjected to a 20 d warm-up period and a 54 d individual feed intake test period. Blood samples were collected on d 50 of the test. A generalized linear regression model was used to determine factors important in the determination of BUN concentrations of individual animals. Factors considered were sire, BUN assay date, age, initial test weight, birth weight, weaning weight, average daily gain, dry matter intake, residual feed intake, pulmonary arterial pressure, ultrasound ribeye area, ultrasound back fat, ultrasound percent intramuscular fat, and feedlot pen. Sire (P < 0.0005; partial r(2) = 0.47), BUN assay date (P < 0.00005; partial r(2) = 0.46) and age (P < 0.005; partial r(2) = 0.18) were all important sources of variation of BUN concentration levels. Sire and assay date explained the largest proportion of variability in BUN concentration as evidenced by their partial r(2) values. Sample process date and age are factors in which cattle producers would have little control in mitigating BUN concentrations, but that could be adjusted for with proper data recording. Differences amongst sires, however, indicate genetic differences may be exploited to reduce BUN concentrations.

Increasing dietary electrolyte balance (dEB) has previously been shown to reduce the inci- dence of nonambulatory and noninjured swine, improve meat quality, and reduce the incidence of gastric ul- cers. The objective of this study was to evaluate the effect of dEB under commercial conditions. Due to the variability in feed withdrawal, transport, and lairage conditions in the swine industry, it was necessary to determine first the persistence of blood changes during the marketing process after alteration of dEB. Sixteen pens of 8 crossbred barrows were assigned to a low (121 mEq/kg) or high (375 mEq/kg) dEB diet, calculated as Na + + K + − Cl − , to determine the persistence of blood changes associated with the alteration of dEB. Diets were formulated to meet or exceed NRC (1998) require- ments for energy, protein, vitamins, and minerals. Di- etary treatments were provided for ad libitum intake for 3 d before slaughter. Before transport, animals were fasted in the barn for approximately 10 h. After fast- ing, animals were shipped to the packing plant, rested for 8 h, and subsequently slaughtered. Initial and final BW of the animals were obtained. Blood was sampled at baseline (2 d before administration of diets), before feed withdrawal (0 h), after feed withdrawal (10 h), and at exsanguination (20 h). Consumption of the high dEB diet for 3 d resulted in an increase in blood TCO 2 (P = 0.001), HCO3 − (P = 0.001), and base excess (P = 0.0003) and a decrease in Cl − (P = 0.0002) and anion gap (P = 0.01). These differences, however, were not maintained for any of the blood components after the 10-h feed withdrawal (P > 0.22). Increasing dEB had no adverse effects (P > 0.18) on growth performance, meat quality, or carcass yield and did not decrease pars esophageal ulcer scores. This study demonstrated that the effect of dEB on blood components was not main- tained after a 10-h feed withdrawal. Therefore, it is likely that the ability of the animal to withstand any increased metabolic acid load associated with the stress of transport was lost after feed withdrawal. Further re- search is needed to determine the effects of dEB altera- tion in animals that have not been fasted before ship- ment and using diets with a larger difference in dEB.

Two experiments were conducted to evaluate effects of ractopamine (RAC) and steroidal implant treatments on performance, carcass traits, blood metabolites, and lipogenic enzyme activity in feedlot cattle. In Exp. 1, yearling steers (n = 486; initial BW = 305 kg) were used in a 3 × 3 factorial arrangement of RAC doses of 0 (R0), 100 (R100), or 200 (R200) mg·steer(-1)·d(-1) fed for 28 d and implant regimens (implant-reimplant) of no implant-no reimplant (NI-NI), 120 mg of trenbolone acetate (TBA) and 24 mg of estradiol-17β (E17B)-no implant (RS-NI), or 80 mg of TBA and 16 mg of E17B followed by 120 mg of TBA and 24 mg of E17B (RI-RS). Except for KPH and skeletal maturity score, no RAC × implant interactions were noted (P > 0.10). Carcasses from R200 were 6.3 kg (P = 0.042) heavier than those from R0. Marbling, calculated empty body fat (EBF), and USDA quality grade did not differ (P > 0.10) among RAC treatments. The RI-RS steers had 12.6 kg (P = 0.001) and 41.1 kg (P 0.10) in EBF, marbling score was decreased for RI-RS (P 0.10) were detected. The RAC-supplemented heifers had greater HCW (P 0.10), TE (P = 0.021) and TO (P = 0.039) had fewer Choice carcasses than NI. Heifers with implants had decreased cortisol and increased IGF-1 and NEFA (P < 0.10) compared with NI heifers. An implant × RAC interaction was detected (P = 0.001) for serum urea nitrogen (SUN), with TE and RAC-supplemented heifers having decreased SUN. These data suggest that the effects of implant and RAC on growth and carcass traits are independent and that USDA quality grade and marbling score can differ significantly among carcasses with similar calculated EBF values.

Two hundred forty Angus crossbred steers were used to determine the influence of feeding various quantities of wet and dry distillers grains to finishing steers on carcass characteristics, meat quality, retail-case life of ground beef, and fatty acid profile of LM. Three replications of 5 dietary treatments were randomly applied to 15 pens in each of 2 yr. A finishing diet containing dry-rolled corn, soybean meal, and alfalfa hay was fed as the control diet. Wet distillers grains with solubles (DGS) or dry DGS was added to the finishing diets at either 20.0 or 40.0% of the dietary DM to replace all soybean meal and part of the cracked corn in treatment diets. Carcasses of steers fed DGS had greater (P < 0.05) fat thickness (1.47 vs. 1.28 cm), greater (P < 0.05) USDA yield grades (3.23 vs. 2.94), and smaller (P < 0.05) percentage of yield grades 1 and 2 (41.1 vs. 60.4%) than carcasses of steers fed the control diet. Longissimus muscle from steers fed dry DGS had greater (P < 0.05) ultimate pH values (5.52 vs. 5.49) than LM from steers fed wet DGS. Ground beef from steers fed DGS had greater (P < 0.05) concentrations of α-tocopherol (1.77 vs. 1.43 μg/g) than ground beef from steers fed the control diet. Ground beef from steers fed 40% DGS had greater (P < 0.05) thiobarbituric acid-reactive substances (2.84 vs. 2.13 mg/kg) on d 2 of retail display than ground beef from steers fed 20% DGS. Longissimus muscle of steers fed DGS had less (P < 0.05) C17:0 and more (P < 0.05) C18:0, C18:1t, C16:1c9, C18:2c9c12 (where t is trans and c is cis), and total PUFA than LM of steers fed the control diet. Feedlot steers fed DGS may need to be marketed earlier than normal to avoid excess external fat and carcasses with a greater numerical yield grade. These data suggest feeding DGS to finishing steers will have no adverse or beneficial effects on glycolytic variables (dark cutters), retail display life of ground beef, or meat tenderness. However, beef from cattle finished on diets containing DGS will likely have a greater proportion of PUFA and therefore may be more susceptible to oxidative rancidity.

A randomized complete block design experiment with 360 single-source black yearling steers (average BW = 316.1 +/- 9.1 kg) fed a 91% concentrate (steam-flaked corn base) diet was conducted to evaluate the effects of supplemental vitamin A (0, 1,103, 2,205, 4,410, or 8,820 IU/kg of dietary DM) on plasma and liver vitamin A and E concentrations, lipogenic enzyme activity, marbling score, and performance of yearling steers. Final BW (586, 580, 590, 585, and 584 kg for 0, 1,103, 2,205, 4,410, and 8,820 IU of supplemental vitamin A/kg of DM, respectively) did not differ (P = 0.39) among treatments. Feed efficiency, ADG, and daily DMI did not differ (P > 0.10) among treatments within each 28-d period or for the overall experiment. From d 57 to slaughter, average DMI (10.33, 10.28, 10.57, 9.75, and 10.22 kg/steer daily for 0, 1,103, 2,205, 4,410, and 8,820 IU of vitamin A/kg of DM, respectively) was less (P 0.10) among treatments. Similarly, the percentage of carcasses grading >or=USDA Choice (62.6, 52.8, 64.0, 58.4, and 58.4% for 0, 1,103, 2,205, 4,410, and 8,820 IU of vitamin A/kg of DM, respectively), Select, or 0.10) among treatments. Except for d 56 (P = 0.050; r = 0.18 for liver retinol), no correlations (P > 0.10) between marbling score and any plasma or liver tissue retinol or alpha-tocopherol concentrations or vitamin A intake were found, and no differences (P > 0.10) in lipogenic enzyme activity were detected among treatments. Taken together with previous and concurrent research, results of this experiment suggest that vitamin A supplementation at a concentration up to twice the NRC recommendation has little effect on performance, marbling, or lipogenic enzyme activity in adipose tissue samples in yearling feedlot steers, and that 2,205 IU of supplemental vitamin A/kg of DM (20,000 IU/steer daily) or less is adequate to meet the vitamin A requirements of finishing beef cattle.

A total of 432 crossbred yearling steers (395 kg +/- 6.35) were used in a randomized block experiment to study the effects of rumen degradable intake protein (DIP) and rumen undegradable intake protein (UIP) concentration on feedlot performance and carcass merit. The 6 dietary treatments used for this study included 1) a 10.5% CP diet with 5.1% UIP and 5.4% DIP (DIP5); 2) an 11.5% CP diet with 5.1% UIP and 6.4% DIP (DIP6); 3) a 12.5% CP diet with 5.1% UIP and 7.4% DIP (DIP7); 4) a 13.5% CP diet with 5.1% UIP and 8.4% DIP (DIP8); 5) a 14.5% CP diet with 5.1% UIP and 9.4% DIP (DIP9); and 6) a 14.5% CP diet with 6.1% UIP and 8.4% DIP with the additional UIP provided by corn gluten meal. There was a linear increase in final BW and ADG and a trend for a linear increase in DMI associated with increasing DIP concentration within the 5.1% UIP treatments. Feed efficiency and NE recovered from the diet were not influenced by dietary DIP concentration. As dietary DIP concentration increased, carcass fat depth and average yield grade increased linearly and the percentage of yield grade 1 and 2 carcasses decreased linearly. Dietary UIP treatment had no effect on final BW, ADG, DMI, G:F, and calculated NE recovery. For the 14.5% CP diets, marbling score tended to be reduced for steers fed 6.1% UIP as compared with 5.1% UIP. The remaining carcass traits were not affected by dietary UIP. The results of this study show that the DIP requirement in the finishing diet for heavy yearling steers fed steam-flaked corn is greater than 7.4% of dietary DM but likely is not more than 8.4% of dietary DM when dietary UIP is approximately 5.1% of dietary DM. Increasing UIP above 5.1% of dietary DM did not improve feedlot performance or HCW. Expressed on a CP basis, it appears as though the requirement for CP for heavy yearling steers fed steam-flaked corn-based finishing diets is 13.5% of DM, with approximately 62% of CP from DIP.

Relationships between behavioral and physiological symptoms of preslaughter stress and LM Warner-Bratzler shear force (WBSF) were investigated using Bos taurus steers (n = 79) and heifers (n = 77). Measurements of heart rate, respiration rate, rectal temperature, and concentrations of serum cortisol and plasma epinephrine were used as indicators of stress associated with physical handling and chute restraint, whereas concentrations of cortisol, glucose, lactate, and creatine kinase in blood samples obtained at exsanguination were measured to reflect physiological reactions of animals to transportation stress. Increased plasma epinephrine concentration, indicative of acute handling stress, was associated with elevated heart rate (r = 0.42, P 0.05) among behavior categories. Grouping cattle according to differences in plasma lactate concentration categorized them according to mean differences in LM WBSF. Moreover, steaks from cattle with the greatest plasma lactate concentrations at slaughter (91st to 100th percentile) had a delayed response to aging that persisted until 14 d postmortem. Stress-induced differences in LM tenderness observed in this study were independent of differences in muscle pH.

Four hundred thirty-two crossbred yearling steers (339 kg +/- 4.8) were used to investigate the effects of water quality and dietary potassium concentration and source on feedlot performance and carcass merit. The study was conducted using a 2 x 3 factorial treatment arrangement. Factors evaluated included 2 water sources: 1) a blend of reverse osmosis and well water (RO; 608 +/- 164 mg/L of SO(4)) and 2) 100% well water with SO(4) concentration of 1,933 +/- 53 mg/L and 3 dietary K treatments. Potassium treatments included 0.75% K with supplemental K from potassium chloride (0.75% K-KCl), 0.75% K with supplemental K from potassium carbonate (0.75% K-K(2)CO(3)), and 1.0% K with supplemental K from potassium carbonate (1.0% K-K(2)CO(3)). Interactions between water quality and dietary treatments were not significant. Dry matter intake tended (P = 0.10) to be greater for steers consuming RO water compared with well water and was not affected by dietary treatment. Feed efficiency (P = 0.04) and NE(g) recovery (P = 0.04) were greater for 1.0% K-K(2)CO(3) compared with 0.75% K-KCl but were not affected by water quality. Final BW was heavier (P < 0.001) and ADG was greater (P = 0.04) for RO water compared with well water but were not affected by diet. Carcasses from steers that consumed RO water tended (P = 0.08) to be heavier than carcasses from steers consuming well water. Dietary treatment did not affect HCW (P = 0.52). Yield grade calculated from carcass measurements was not affected by dietary treatment or water quality. Carcasses from steers consuming well water had greater (P = 0.04) marbling scores than RO water. These data demonstrate that steers consuming RO water achieved improved feedlot performance. Steers fed 1.0% K-K(2)CO(3) were more efficient and demonstrated improved energy recovery compared with steers fed 0.75% K-KCl. Improved efficiency and energy recovery may be related to a reduction (P = 0.06) in the liver abscess rate for steers consuming 1.0% K-K(2)CO(3). Dietary cation-anion balance was positively related to ADG (P < 0.01) and NE(g) (P = 0.03) recovery but negatively related to marbling score (P = 0.04).

Calf-fed heifers (n = 72) and steers (n = 72) were supplemented with 4 levels (0, 0.25, 0.50, and 0.75%) of dietary Mg as MgO during the final 14 d of finishing and were commingled 1 d before slaughter (inducing stress by mixing unfamiliar cattle) to examine the effects of sex class and Mg supplementation on stress responses and LM quality characteristics. Heifers and steers exhibited markedly different stress responses. Heifers were more excitable than steers during preslaughter handling events and exhibited a short-term physiological stress response that involved acute sympatho-adrenal activation and resulted in increased meat toughness, without a concomitant increase in muscle pH. Steers, on the other hand, exhibited greater physical activity, associated with agonistic behavior, during the mixing period and therefore produced carcasses with lesser (P = 0.008) LM glycogen concentrations and greater (P = 0.042) 48-h LM pH values, compared with heifers. Steers also produced tougher (P = 0.008) LM steaks than did heifers. Within the range of pH values observed in this study (5.3 to 6.1), positive, linear relationships between 48-h LM pH and mean LM shear force (P 0.05) once LM samples had been aged for 21 d. Results suggested that toughness of LM steaks from beef carcasses with final LM pH values greater than 5.65 could be problematic unless LM cuts are aged for approximately 18 d or longer. Supplementation with dietary Mg increased (P = 0.011) serum Mg concentration, but had no effect (P > 0.05) on any of the physiological stress indicators or LM quality characteristics measured in this study. There was no evidence to support the premise that Mg supplementation of cattle lessens the effects of preslaughter stress on beef quality characteristics.

Effects of ractopamine hydrochloride (RAC) supplementation and postmortem aging on palatability of beef from steers differing in biological type were evaluated using LM samples from British, Continental crossbred, and Brahman crossbred calf-fed steers (n = 98/type). Equal numbers of steers within each type were assigned to treatments of 0 or 200 mg.steer(-1).d(-1) of RAC fed during the final 28 d of the finishing period. Warner-Bratzler shear force (WBSF) was measured at 3, 7, 14, and 21 d postmortem, and trained sensory panel (TP) evaluation was conducted using LM samples aged for 14 d postmortem. A RAC x type interaction (P = 0.006) was detected for WBSF. Within each type, steers fed RAC produced steaks with greater (P0.05) WBSF values than steaks from control steers; however, the magnitude of the effect of RAC on WBSF was more pronounced among Brahman cross-breds (5.53 vs. 4.96 +/- 0.10 kg) than among Continental crossbred (4.16 vs. 3.96 +/- 0.10 kg) and British steers (4.10 vs. 3.75 +/- 0.10 kg). The effect of RAC on WBSF, though diminished slightly by aging (mean WBSF difference: 3 d = 0.49 kg; 21 d = 0.24 kg), was not completely mitigated by 21 d of postmortem storage (P(RAC x AGE) = 0.16). Steers fed RAC produced steaks that received lower (P0.05) TP ratings for tenderness (8.09 vs. 8.95 +/- 0.18) and juiciness (7.41 vs. 8.07 +/- 0.16 kg), along with slightly lower (P = 0.06) ratings for beef flavor (6.67 vs. 6.93 +/- 0.10 kg), compared with steaks from unsupplemented steers, regardless of biological type. Among the 3 biological types, Brahman crossbred cattle produced steaks with the greatest (P0.05) WBSF values at each aging period; WBSF values for steaks from British and Continental type steers did not differ (P0.05) at any aging time. Sensory panel ratings of tenderness, juiciness, and beef flavor were greatest (P0.05) for steaks from British steers, and least (P0.05) for steaks produced by Brahman-type steers. Results from this study suggest that RAC supplementation slightly decreases LM tenderness (WBSF and TP) of British, Continental crossbred, and Brahman cross-bred steers, and that the effect of RAC on WBSF may be more pronounced in steaks from Brahman crossbred cattle than among stenks from Continental type or British steers.

Effects of finishing implants on heifer carcass characteristics and LM Warner-Bratzler shear force (WBSF) were investigated using commercially fed Continental x British heifers (n = 500). Heifers were blocked by initial BW (block 1, BW > or = 340 kg; block 2, BW 0.05) in adjusted fat thickness or predicted percentage of empty body fat. Compared with a nonimplanted control, implanting heifers once during finishing increased (P = 0.025) HCW by an average of 7.9 kg without affecting the mean marbling score, the percentage of carcasses grading Choice and Prime, or LM WBSF values. Compared with the use of 1 implant, the use of 2 finishing implants resulted in an additional increase (P = 0.008) in HCW of 6.0 kg. Reimplanting also increased (P < 0.001) LM area, reduced (P = 0.024) the percentage of KPH, and improved (P = 0.004) mean yield grade. However, reimplanted heifers produced a lower (P = 0.044) percentage of carcasses grading Choice and Prime and LM steaks with greater (P < 0.05) WBSF values at all postmortem aging times compared with heifers that were implanted once. Among heifers receiving 2 implants, mean 14-d LM WBSF increased linearly (P < 0.05) as the cumulative, combined dosage of E2 plus TBA increased. Heifers implanted with a combination of E2 plus TBA had larger (P = 0.046) LM areas, lower (P = 0.004) mean marbling scores, and greater LM WBSF values after 3 d (P = 0.001), 7 d (P = 0.001), 14 d (P = 0.003), and 21 d (P = 0.045) of postmortem aging than did heifers implanted with TBA alone. Heifers that received combination implants containing both E2 and TBA also produced fewer (P = 0.005) carcasses with marbling scores of modest or greater compared with heifers that received single-ingredient implants containing TBA alone. Implant treatment effects on LM WBSF gradually diminished as the length of the postmortem aging period increased. Postmortem aging periods of 14 to 28 d were effective for mitigating the detrimental effects of mild or moderately aggressive heifer implant programs on the predicted consumer acceptability of LM steaks.

Equal numbers of British, Continental crossbred, and Brahman crossbred calf-fed steers (n = 420) were used to examine the effects of ractopamine supplementation and biological type on behavior during routine handling. Steers were blocked by BW within type and allocated to pens, resulting in 2 pens (10 cattle per pen) representing each block x type subclass. Pens within each block x type subclass then were randomly assigned to ractopamine supplementation treatments (0 or 200 mg.steer(-1).d(-1)), which were administered during the final 28 d of the finishing period. At the time final BW were obtained (28 d after treatment initiation), a single, trained observer, blinded with respect to treatment designations, recorded subjective scores to characterize behavior of each animal. Scores included entry force score (degree of force required to load the animal into the chute); entry speed score (walk, trot, run); chute behavior score (calm, restless shifting, moderate struggling); and exit speed score (walk, trot, run). Ractopamine supplementation had no effect on entry force score, chute behavior score, or exit speed score; however, cattle supplemented with ractopamine entered the chute more rapidly than did control cattle. Biological cattle type was a significant source of variation in entry force score and exit speed score. Continental crossbreds required greater (P < 0.05) force to enter the squeeze chute than did Brahman crossbred or British steers. In addition, Continental crossbred and Brahman crossbred steers left the processing chute with the greatest speed, whereas British steers exited the processing chute most slowly. Biological cattle type did not affect scores for entry speed or behavior during restraint in the chute. No adverse effects of ractopamine supplementation on cattle behavior were observed in this study.

Our objectives were 2-fold: to determine the effect of dietary linoleate on milk fat composition and on transcript abundance of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), lipoprotein lipase (LPL), and stearoyl-CoA desaturase (SCD) mRNA in mammary tissue, and to evaluate milk somatic cell mRNA as a source of mammary tissue mRNA for these enzymes. Eighteen primiparous, crossbred beef cows (BW = 411 +/- 24 kg; BCS = 5.25) were offered Foxtail millet hay at 1.68% of BW daily and either a low-fat control (n = 9) or a high-linoleate (79% 18:2n-6), cracked safflower seed supplement (n = 9). Diets were isonitrogenous and isocaloric, and the linoleate diet contained 5.4% of DMI as fat. At slaughter (37 +/- 3 d postpartum), mammary tissue was sampled and immediately frozen in liquid N2 before being stored at -80 degrees C. Milk samples were obtained from the same mammary glands and immediately centrifuged at 1,200 x g to pellet somatic cells. A ribonuclease protection assay was used to quantify the mRNA in the mammary gland and milk somatic cells. Effects of diet, tissue, or their interaction were not observed for ACC (P = 0.28, 0.89, and 0.35, respectively), FAS (P = 0.38, 0.66, and 0.20, respectively), LPL (P = 0.09, 0.15, and 0.43, respectively), or SCD (P = 0.45, 0.19, and 0.29, respectively). Dietary effects on fatty acid profile of the milk fat suggested that linoleate supplementation might have decreased de novo lipogenesis while increasing uptake of dietary fatty acids; this effect was consistent with a trend toward greater LPL mRNA for linoleate-fed cows (P = 0.09). Correlations (r values) between mammary tissue and milk somatic cell data for each mRNA for the low-fat control diet were: ACC, 0.76 (P = 0.02); FAS, 0.69 (P = 0.04); LPL, 0.68 (P = 0.04); and SCD, 0.73 (P = 0.05), and for the linoleate diet were: ACC, 0.85 (P = 0.003); FAS, 0.75 (P = 0.02); LPL, 0.90 (P = 0.001); and SCD, 0.73 (P = 0.03). We conclude that milk somatic cells obtained from lactating beef cows can be used as a source of RNA to study nutritional regulation of mammary gland lipogenesis in cows fed dietary fat supplements.

This study was conducted to determine the effect of Se supplementation and source on the Se status of horses. Eighteen 18-mo-old nonexercised horses were randomly assigned within sex to 1 of 3 treatments: 1) control (CTRL, no supplemental Se, 0.15 mg of Se/kg of total diet DM); 2) inorganic Se (INORG, CTRL + 0.45 mg of Se/kg of total diet DM from NaSeO3); or organic Se [ORG, CTRL + 0.45 mg of Se/kg of total diet DM from zinc-L-selenomethionine (Availa Se, Zinpro, Corp., Eden Prairie, MN)]. Horses were acclimated to the CTRL diet (7.1 kg of DM alfalfa hay and 1.2 kg of DM concentrate per horse daily) for 28 d. After the acclimation period, the appropriate treatment was top-dressed on the individually fed concentrate for 56 d. Jugular venous blood samples were collected on d 0, 28, and 56. Middle gluteal muscle biopsies were collected on d 0 and 56. Muscle and plasma were analyzed for Se concentrations. Glutathione peroxidase activity was measured in muscle (M GPx-1), plasma (P GPx-3), and red blood cells (RBC GPx-1). Data were analyzed as a repeated measures design. Mean plasma Se concentration on d 28 and 56 was greater (P < 0.05) for Se-supplemented horses compared with CTRL horses, and tended (P < 0.1) to be greater in ORG vs. INORG on d 28. Mean muscle Se concentration and P GPx-3 activities increased (P < 0.05) from d 0 to 56 but were not affected by treatment. Mean RBC GPx-1 activity tended to be greater (P < 0.1) in ORG than INORG or CTRL horses on d 28, and tended to be greater (P < 0.1) for INORG compared with ORG horses on d 56. Mean RBC GPx-1 activity of INORG and ORG horses was not different from that of CTRL on d 56. Mean M GPx-1 activity decreased (P < 0.01) from d 0 to 56. In conclusion, zinc-L-selenomethionine was more effective than NaSeO3 at increasing plasma Se concentration from d 0 to 28; however, both supplemental Se sources had a similar effect by d 56. No difference in Se status due to Se supplementation or source could be detected over a 56-d supplementation period by monitoring middle gluteal muscle Se, M GPx-1, or P GPx-3. Results for RBC GPx-1 also were inconclusive relative to the effect of Se supplementation and source.