Influence of BOVAMINE DEFEND Plus on growth performance, carcass characteristics, estimated dry matter digestibility, rumen fermentation characteristics, and immune function in finishing beef steers

One hundred and eighty crossbred beef steers (406.0 ± 2.2 kg) were used to determine the impact of a novel direct-fed microbial (DFM) on growth performance, carcass characteristics, rumen fermentation characteristics, and immune response in finishing beef cattle. Steers were blocked by body weight (BW) and randomly assigned, within block, to 1 of 2 treatments (3 replicates/treatment: 30 steers/replicate). Treatments included: (1) no DFM (control) and (2) DFM supplementation at 50 mg ∙ animal-1 ∙ d-1 (BOVAMINE DEFEND Plus). All steers were fed a high-concentrate finishing diet and individual feed intake was recorded daily via the GrowSafe system. BWs were collected every 28 d. On day 55, 10 steers per pen were injected with ovalbumin (OVA). Jugular blood samples were collected from each steer on days 0, 7, 14, and 21 post injection. On day 112, the same steers were injected again with OVA and intramuscularly with a pig red blood cell solution. Jugular blood samples were collected from each steer on days 0, 7, 14, and 21 post injection. On day 124, rumen fluid was collected from 3 steers per treatment and used to estimate in vitro rumen fermentation characteristics. Equal numbers of steers per treatment were transported to a commercial abattoir on days 145, 167, and 185 of the experiment, harvested, and carcass data were collected. Initial BW was similar across treatments. On days 28 and 55, steers receiving DFM had heavier BW (P < 0.01) compared to controls. The average daily gain was greater in DFM-supplemented steers from days 0 to 28 (P < 0.01) and days 0 to 55 (P < 0.01) of the experiment compared to controls. Overall dry matter intake (DMI) was greater (P < 0.04) and overall feed efficiency was similar in DFM-supplemented steers compared to controls. Dressing percentage (P < 0.02) was greater in steers receiving DFM compared to controls. Antibody titers to injected antigens were similar across treatments. However, red blood cell superoxide dismutase activity was greater (P < 0.05) in DFM-supplemented steers compared to controls. In vitro molar proportions of isobutyric and butyric acid were greater (P < 0.01) and dry matter (DM) digestibility tended (P < 0.07) to be greater in rumen fluid obtained from steers supplemented with DFM. These data suggest that BOVAMINE DEFEND Plus supplementation improves growth performance during the initial period of the finishing phase, increases overall DMI and dressing percentage, and may impact antioxidant status in beef cattle.

Trace mineral source and chromium propionate supplementation affect performance and carcass characteristics in feedlot steers

Angus-crossbred steers (n = 400; 369.7 ± 7.6 kg) were used to determine the influence of trace mineral (TM) source and chromium propionate (Cr Prop) supplementation on performance, carcass characteristics, and ruminal and plasma variables in finishing steers. Steers were blocked by body weight (BW) and randomly assigned within block to treatments in a 2 × 2 factorial arrangement, with factors being: 1) TM source (STM or HTM) and 2) Cr supplementation (0 or 0.25 mg Cr/kg DM, -Cr or + Cr, respectively). Treatments consisted of the addition of: 1) sulfate TM (STM; 90, 40, and 18 mg/kg DM of Zn, Mn, and Cu, respectively), 2) STM and 0.25 mg Cr/kg DM from Cr Prop, 3) hydroxychloride TM (HTM; 90, 40, and 18 mg/kg DM of Zn, Mn, and Cu, respectively), and 4) HTM and 0.25 mg Cr/kg DM from Cr Prop. Each treatment consisted of 10 replicate pens with 10 steers per pen. Body weights were obtained on consecutive days at the initiation and termination of the 154-d study. Steers were fed a steam-flaked corn-based finishing diet. Ractopamine hydrochloride was fed for the last 31 d of the study. Ruminal fluid and blood samples were obtained from one steer per pen on days 28 and 84 for ruminal volatile fatty acids (VFA) and plasma TM and glucose analysis. Steers were slaughtered at the end of the study and individual carcass data were collected. No Cr × TM source interactions (P = 0.48) were detected. Steers supplemented with HTM had greater (P = 0.04) hot carcass weight (HCW), dressing percentage (DP), longissimus muscle (LM) area, and USDA yield grade (YG), and tended (P = 0.12) to have greater average daily gain (ADG) than those receiving STM. Average daily gain, gain:feed, dressing percentage, and longissimus muscle area were greater (P = 0.04) for + Cr steers compared to-Cr steers. Hot carcass weight tended (P = 0.06) to be greater for + Cr steers. Ruminal acetate concentrations at 28 d were lesser (P = 0.01) for HTM vs. STM steers, and greater (P = 0.04) for + Cr steers compared to-Cr steers. Plasma concentrations of Zn, Cu, and Mn were not affected by TM source or Cr supplementation. Steers supplemented with Cr had greater (P = 0.05) plasma glucose concentrations than-Cr steers at 28 but not at 84 d. Results of this study indicate replacing STM with HTM improved carcass characteristics in finishing steers, and Cr Prop supplementation improved steer performance and carcass characteristics.

Vitamins and Trace Minerals in Ruminants: Confinement Feedlot

Trace minerals and vitamins are essential for optimizing feedlot cattle growth, health, and carcass characteristics. Understanding factors that influence trace mineral and vitamin absorption and metabolism is important when formulating feedlot cattle diets. Current feedlot industry supplementation practices typically exceed published trace mineral requirements by a factor of 2 to 4. Therefore, the intent of this review is to briefly discuss the functions of trace minerals and vitamins that are typically supplemented in feedlot diets and to examine the impact of dose of trace mineral or vitamin on growth performance, health, and carcass characteristics of feedlot cattle.

The Effects of Long-term Molybdenum Exposure in Drinking Water on Molybdenum Metabolism and Production Performance of Beef Cattle Consuming a High Forage Diet

Fifty-four multiparous beef cows with calves were used to evaluate the effects of Mo source (feed or water) on reproduction, mineral status, and performance over two cow-calf production cycles (553 days). Cows were stratified by age, body weight, liver Cu, and Mo status and were then randomly assigned to one of six treatment groups. Treatments were (1) negative control (NC; basal diet with no supplemental Mo or Cu), (2) positive control (NC + Cu; 3 mg of supplemental Cu/kg DM), (3) NC + 500 µg Mo/L from Na2MoO4·2H2O supplied in drinking water, (4) NC + 1000 µg Mo/L of Na2MoO4·2H2O supplied in drinking water, (5) NC + Mo 1000-water + 3 mg of supplemental Cu/kg DM, and (6) NC + 3.0 mg of supplemental Mo/kg diet DM from Na2MoO4·2H2O. Animals were allowed ad libitum access to both harvested grass hay (DM basis: 6.6% crude protein; 0.15% S, 6.7 mg Cu/kg, 2.4 mg Mo/kg) and water throughout the experiment. Calves were weaned at approximately 6 months of age each year. Dietary Cu concentration below 10.0 mg Cu/kg DM total diet reduced liver and plasma Cu concentrations to values indicative of a marginal Cu deficiency in beef cows. However, no production parameters measured in this experiment were affected by treatment. Results suggest that Mo supplemented in water or feed at the concentrations used in this experiment had minimal impact on Cu status and overall performance.

Liver abscess microbiota of feedlot steers finished in natural and traditional management programs

Liver abscess etiology in feedlot steers involves the escape of bacteria from the digestive tract to form a polymicrobial abscess within or on the external surface of the liver. However, little is known about the effects of feedlot finishing systems on the microbial composition of the liver abscess purulent material. Liver abscesses were collected at the time of harvest from steers originating from a single feedlot managed in either a traditional program (which included tylosin phosphate supplementation) or a natural program (without tylosin phosphate supplementation). The purulent material of liver abscesses from traditionally managed steers (N = 53 abscesses) and that of naturally managed steers (N = 62 abscesses) was characterized using the V4 region of the 16S rRNA gene. Two phyla and three genera were found in greater than 1% relative abundance across all abscesses. The genus Fusobacterium was identified in all liver abscess samples and accounted for 64% of sequencing reads. Bacteroides and Porphyromonas genera accounted for 33% and 1% of reads, respectively. Trueperella was more likely to be found in the liver abscesses of naturally managed steers than traditionally managed steers (P = 0.022). Over 99% of the genus-level bacterial sequences observed across all liver abscesses belonged to Gram-negative genera. Bacteria known to colonize both the rumen and hindgut were identified within liver abscesses. No differences in alpha diversity or beta diversity were detected between liver abscess communities (between the two management programs or individual pens) when tested as richness, Shannon Diversity Index, or weighted UniFrac distances (P > 0.05). These results were consistent with previous identification of Fusobacterium necrophorum as the primary bacteriologic agent within liver abscesses and emphasized the relationship between the gastrointestinal microbiota and liver abscess formation. Though the microbiota of the liver abscess purulent material was similar between steers fed an antibiotic-free diet and those fed an antibiotic-containing diet from the same feedlot, divergence was detected in liver abscess communities with some being dominated by Fusobacterium and others being dominated by Bacteroides.

PSII-B-18 Açai Seed as Fiber Source on Intake, Digestibility and Ruminal Parameters in Zebu Beef Cattle fed a High Concentrate Diet

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 &lt; 0.05, and tendency at 0.05 &gt; P &lt; 0.10. A linear increase was observed for DM (P= 0.07), organic matter (P &lt; 0.05), crude protein (CP, P &lt; 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&lt; 0.05) in NDF digestibility was detected with the inclusion rate of AS. DM, CP digestibility, and metabolic energy were similar across treatments (P &gt; 0.10). Ruminal and intestinal DM and nutrient digestibility were similar between the treatments (P &gt; 0.10). Rumen concentrations of acetic acid increased (P &lt; 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.

PSIX-15 The Influence of Trace Mineral Source on Reproductive Performance in Recipient Multiparous Beef Cows

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 &lt; 0.05) and Cu (P &lt; 0.05) concentrations when compared to ITM. There was a treatment x time interaction for Cu concentrations (P &lt; 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.

PSIX-13 The Impact of Saccharomyces Cerevisiae Fermentation Product on in-Vitro Rumen Fermentation Characteristics, gas Production, and Ruminal Microbiome Composition

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 &lt; 0.04) and molar proportions of propionic acid (P &lt; 0.03) were greater for treatments containing NaturSafe compared with control. Molar proportions of acetic acid (P &lt; 0.07), percent CH4 (P &lt; 0.08), and NH3-N (P &lt; 0.06) tended to be lesser and percent CO2 tended (P &lt; 0.07) to be greater for NaturSafe treatments compared with controls. Microbiome 16S rRNA analysis results suggest that microbial communities differed (P &lt; 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 &lt; 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.

PSV-A-12 The Influence of Calcium Dose and Olive Meal on in-Vitro Rumen Fermentation Characteristics

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 &lt; 0.001) DMD when compared to all other Ca doses. At 12h post incubation, DMD was greater (P &lt; 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 &lt; 0.03) in digestion tubes containing olive meal compared to no olive meal and were greater (P &lt; 0.001) in digestion tubes containing 0.08% Ca compared to all other Ca doses. At 12h post incubation, isobutyric acid (P &lt; 0.01) and butyric acid (P &lt; 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 &lt; 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.

PSIII-16 The Influence of Olive Byproduct Supplementation on American Wagyu Feedlot Performance and Carcass Characteristics

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 &lt; 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 &lt; 0.05) and C18:0 lesser (P &lt; 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.

PSVIII-13 Influence of Propionibacteria Acidipropionici on Short Chain Fatty Acid and Methane Production in Fistulated Beef Steers

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 &lt; 0.05) in steers receiving PA compared with controls. In vitro DM disappearance (P &lt; 0.05; 63.3% vs 59.2%±1.12) and total VFA (P &lt; 0.05; 147.9 vs 145.2±1.76) were greater and methane (ml/g DMD) lesser (P &lt; 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 &lt; 0.03) and propionic acid (P &lt; 0.04) increased linearly as dose of PA increased. In vitro Total VFA tended (P &lt; 0.08) to increase linearly and methane production tended (P &lt; 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.

393 Young Scholar Award Talk: Investigation of Pain and Analgesic Strategies in Cattle Undergoing Painful Husbandry Procedures and Disease Conditions

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 &lt; 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 &lt; 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.

Bacteroidetes and Firmicutes Drive Differing Microbial Diversity and Community Composition Among Micro-Environments in the Bovine Rumen

Ruminants are a critical human food source and have been implicated as a potentially important source of global methane emissions. Because of their unique digestive physiology, ruminants rely upon a symbiotic relationship with the complex and rich community of microorganism in the foregut to allow digestion of complex carbohydrates. This study used 16S rRNA gene sequencing to investigate the composition of microbial communities from three rumen micro-environments of cattle fed identical diets: (1) free fluid, (2) the fibrous pack, and (3) the mucosa. Community composition analysis revealed that while a phylogenetic core including the most abundant and most common ruminal taxa (members of Bacteroidetes and Firmicutes) existed across micro-environments, the abundances of these taxa differed significantly between fluid- and mucosa-associated communities, and specific lineages were discriminant of individual micro-environments. Members of Firmicutes, specifically Clostridiales, Lachnospiraceae, Mogibacteriaceae, Christenellaceae, and Erysipelotrichaceae were significantly more abundant in fluid communities, while members of Bacteroidetes, namely Muribaculaceae and Prevotellaceae were more abundant in mucosa-associated communities. Additionally, Methanobacteriaceae, a family of methanogenic Archaea, was more abundant in fluid-associated communities. A set of four more diverse lineages were discriminant of pack-associated communities that included Succinivibrionaceae, RFP12 (Verruco-5), Fibrobacteraceae, and Spirochaetaceae. Our findings indicate that different ecological niches within each micro-environment have resulted in significant differences in the diversity and community structure of microbial communities from rumen fluid, pack, and mucosa without the influence of diet that will help contextualize the influence of other environmental factors.

Impact of Cell Culture and Copper Dose on Gene Expression in Bovine Liver

The objectives of these experiments were to investigate (1) the relative abundance of transcripts for Cu-responsive genes in whole bovine liver vs. cultured hepatocytes and (2) the influence of Cu dose on the relative abundance of transcripts for Cu-responsive genes in cultured bovine hepatocytes. Experiment 1: Liver samples were obtained immediately post-mortem from one healthy Angus steer. Half of the tissue samples were placed in RNAlater solution; the remaining half was used to isolate hepatocytes. Experiment 2: A subset of cultured hepatocytes was incubated in media containing: 0 mg/L, 0.10 mg/L, 1.0 mg/L, 10.0 mg/L, and 100 mg/L Cu for 1 h. Transcripts analyzed were aldehyde dehydrogenase (ALDH2), apolipoprotein A-1 (APOA1), antioxidant 1 (ATOX1), ATPase copper transporting alpha (ATP7A), ATPase copper transporting beta (ATP7B), betaine homocysteine methyltransferase (BHMT), flavin reductase (BLVRB), carbonic anhydrase II (CA2), copper chaperone for superoxide dismutase (CCS), cytochrome c oxidase copper chaperone (COX17), Cu transporter 1 (CTR1), glutamate dehydrogenase (GLUD1), glutathione synthetase (GSS), protein disulfide isomerase A3 (PDIA3), and superoxide dismutase (Cu-Zn) (SOD1). Β-Actin (ACTB) was selected as the endogenous control in both experiments. Experiment 1: Whole liver had greater (P < 0.01) relative abundance of mRNA for APOA1, ATOX1, ATP7A, ATP7B, COX17, CTR1, ALDH2, BHMT, BLVRB, CA2, GLUD1, and GSS when compared with cultured hepatocytes. Experiment 2: Copper dose impacted all identified transcripts. These results indicate that the relative abundance of Cu-responsive transcripts is different in whole vs. cultured hepatocytes and that the relative abundance of Cu-responsive genes is dependent on Cu dose in cultured hepatocytes.

The effect of breed, sex and oral meloxicam administration on pain biomarkers following hot-iron branding in Hereford and Angus calves

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 (P < 0.01) 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; P < 0.01). 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; P < 0.01). MEL took fewer lying bouts at 0–12 h (4.91 bouts ± 0.56) compared with CON (6.87 bouts ± 0.55; P < 0.01). 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.

Characterizing heat mitigation strategies utilized by beef processors in the United States

During lairage at slaughter plants, cattle can be exposed to extreme heat conditions from pen densities and holding pen microclimates. While research outlining heat mitigation strategies used in other sectors of the beef supply chain is available, there is no published data on the use of heat mitigation strategies at slaughter plants. The objective of this study was to characterize short-term heat mitigation strategies used by commercial beef slaughter plants in the United States. Twenty-one beef slaughter plants, representing an estimated 60% of beef slaughter in the United States, were included in the study. All plants indicated use of at least one heat mitigation strategy, and five of them used more than one type. Sprinklers/misters were the most commonly used heat mitigation type (n = 17, 81%), and fans were the least common type (n = 4, 19%). Shade usage was present in several plants (n = 7, 33%), ranging from barn style roofs to shade cloths. Respondents indicated that they believed heat mitigation strategies provide benefits both to cattle well-being and meat quality outcomes. Future research should focus on the effectiveness of these techniques in improving animal well-being and quality outcomes in the slaughter plant environment and protocols for optimum implementation.

PSIII-14 The influence of dietary barley supplementation on American Wagyu feedlot performance

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.

PSXVI-22 The influence of Propionibacteria on in vivo rumen fermentation characteristics and in vitro lactic acid clearance rate in fistulated steers fed moderately high concentrate diets

Six steers fitted with ruminal cannulae were used in a crossover design to examine the impact of direct fed microbial (DFM) supplementation on in vivo rumen fermentation characteristics and in vitro lactic acid clearance. Steers were fed a moderately high concentrate -1∙day-1 of 4.45x 1010 CFU/g of Propionibacteria acidipropionici). Treatments were administered daily, directly into the rumen via the cannula as a single bolus dose at the time of feeding. Rumen contents were sampled two h post-feeding daily and analyzed for short chain fatty acids (SCFA). On d 7 and 14, rumen fluid was collected from all steers and subjected to an in vitro lactic acid clearance challenge. Lactic acid and SCFA concentrations were determined at 3, 6 and 9 h post incubation. After d 14, all cattle received the basal diet for 21 d. On d 22, treatment crossover was implemented and the experiment repeated. Animal was considered the experimental unit and data were analyzed as a crossover design using Proc Mixed in SAS. In vivo propionic acid concentrations were greater (P &lt; 0.05) and total SCFA tended (P &lt; 0.06) to be greater in rumen fluid from steers receiving DFM. D- and total lactic acid concentrations were lesser (P &lt; 0.05) at 3 h post in vitro incubation for steers receiving DFM. D-, L+, and total lactic acid concentrations were similar between treatments at all other timepoints. In vitro propionic acid and total SCFA concentrations were greater (P &lt; 0.05) and acetic acid concentrations lesser (P &lt; 0.05) in steers receiving DFM. These data indicate that the DFM Propionibacteria acidipropionici, alters in vivo and in vitro rumen fermentation characteristics.

PSIV-10 Effects of chronic molybdenum exposure in drinking water or feed on molybdenum and copper status and production performance of gestating and lactating beef cattle consuming a low-quality forage diet

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 &lt; 0.01) interaction for cow liver Cu concentrations. Cows not receiving supplemental Cu had lower (P &lt; 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.

PSX-A-12 Late-Breaking: Effects of Renergy™ on ruminal fermentation in steers fed a high-grain diet

Renergy™ is a proprietary blend of organic acids with a proposed mode of action of increasing ruminal propionate production. Little is known about the efficacy of Renergy™ supplementation in modifying ruminal fermentation in beef cattle consuming high-grain diets. Therefore, eight Angus steers (BW 531.7 ± 20.4 kg) fitted with ruminal cannulae were used to determine the effects of Renergy™ on ruminal fermentation characteristics. Steers were fed a high concentrate diet (DM basis: 13.6% CP, 1.38 Mcal/kg NEg, and 2.02 Mcal/kg NEm) with no monensin sodium or tylosin phosphate added to the diet for 30 d prior to the initiation of the experiment. Treatments consisted of control (CON; no supplemental Renergy™) and Renergy (REN) fed at 27.6 g.animal-1.d-1 (n = 4 steers/treatment; experimental unit = animal). Following the 30 d diet adaptation period, dietary treatments were initiated for 28-d. On day 28, rumen fluid was collected at 3 h post feeding and analyzed for VFA, pH, and NH3. Ruminal pH (P = 0.62) and NH3 (P = 0.56) were unaffected by treatment. However, total VFA (P = 0.05) and propionate (P = 0.03) production were increased by Renergy, 13.3% and 25.7% respectively. There was a tendency (P = 0.14) for acetate production to be increased 10.9% in steers supplemented with Renergy™. Butyrate was unaffected (P = 0.51) by treatment. However, isobutyrate production was lower (P &lt; 0.01) in steers receiving Renergy™. Feeding Renergy™ also resulted in 25% less (P = 0.07) L-lactate production. Under conditions of this experiment, results indicate that supplementing Renergy™ for 28d to beef cattle consuming high concentrate diets impacts ruminal fermentation 3 h post feeding.

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PSXVI-23 The influence of trace mineral source on digestion, ruminal fermentation characteristics, and mineral solubility in beef cattle fed a high concentrate feedlot diet

Twelve Angus steers (BW 530.9 ± 22.7kg) fitted with ruminal cannulae were used to determine the impact of trace mineral (TM) source on digestibility and ruminal VFA and soluble concentrations of Cu, Mn, and Zn. Steers were fed a high concentrate diet balanced to meet the requirement of finishing feedlot steers for 21d. Treatments consisted of Cu, Mn, and Zn supplemented at 18, 40, and 90 mg/kg DM, respectively, from either sulfate (STM) or hydroxy trace mineral (HTM) sources (n = 6 steers/treatment; experimental unit = steer). Following a 21-d adaptation period total fecal output was collected for 5 d. Trace mineral sources had no impact on nutrient digestibility. On d 6, rumen fluid was collected at 0, 2, and 4 h post-feeding for VFA analysis. There were no treatment x time interactions for any VFA measured. However, HTM steers had greater (P &lt; 0.05) ruminal molar proportions of propionate and tended (P &lt; 0.07) to have greater molar proportions of valerate compared to STM steers. Steers fed STM had greater (P &lt; 0.05) molar proportions of butyrate compared to HTM steers. Steers were then fed the same high concentrate diet without supplemental Cu, Zn, or Mn for 14 d. On d 15 steers received a pulse dose (via rumen cannula) from either STM or HTM. Ruminal samples were obtained at 2 h intervals starting at -4 and ending at 24 h relative to dosing. There was a treatment x time interaction (P &lt; 0.05) for ruminal soluble Cu concentrations. Ruminal soluble mineral concentrations were greater (P &lt; 0.05) for Cu at 4, 6, 8, and 16 h post-dosing in STM compared to HTM supplemented steers. Results indicate that ruminal solubility of Cu differs between STM and HTM sources and may impact rumen fermentation characteristics.

Molybdenum Exposure in Drinking Water Vs Feed Impacts Apparent Absorption of Copper Differently in Beef Cattle Consuming a High-Forage Diet

Twelve Angus steers were utilized to investigate the influence of molybdenum (Mo) in drinking water or feed on apparent absorption and retention of copper (Cu) and Mo. Steers were fed a low-quality grass hay diet for 14 days. Steers were then housed in individual metabolism stalls and blocked by body weight and dry matter intake (DMI) and randomly assigned within block to one of three treatments. Treatments consisted of (1) control (no supplemental Mo), (2) 5.0 mg Mo/kg DM from sodium molybdate dihydrate (Mo-diet), and (3) 1.5 mg Mo/L from sodium molybdate dihydrate delivered in the drinking water (Mo-water). Total fecal and urine output were then collected for 5 days. Dry matter, Cu and water intake, and DM digestibility were similar across treatments. Molybdenum intake was greater (P < 0.05) in Mo-water and Mo-diet steers when compared to controls but similar between Mo-water and Mo-diet steers. Apparent absorption and retention of Cu were greater (P < 0.05) in controls when compared to Mo-diet supplemented steers. Apparent absorption and retention of Cu in steers in the Mo-water treatment did not differ from controls or those receiving the Mo-diet. Molybdenum-diet and Mo-water supplemented steers had similar apparent absorption and retention of Cu. Apparent absorption and retention of Mo (% of Mo intake) was greater in controls when compared to Mo-supplemented steers. These data indicate that Mo consumed in water may impact Cu absorption and retention to a lesser extent than Mo supplemented in the diet.

Impacts of shade on cattle well-being in the beef supply chain

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.

Effects of differing withdrawal times from ractopamine hydrochloride on residue concentrations of beef muscle, adipose tissue, rendered tallow, and large intestine

Ractopamine hydrochloride (RAC) is a beta-agonist approved by the U.S. Food and Drug Administration (FDA) as a medicated feed ingredient for cattle during the final days of finishing to improve feed efficiency and growth. Maximum residue limits and U.S. FDA residue tolerances for target tissues have defined management practices around RAC usage in the U.S. However, many countries have adopted zero tolerance policies and testing of off-target tissues, presenting a major challenge for international export. Therefore, the objective this study was to determine the necessary withdrawal time among cattle group-fed RAC to achieve residue concentrations below tolerance levels in muscle and off-target tissues. Specifically, both total and parent RAC residues were quantified in muscle, adipose tissue, rendered tallow, and large intestines from animals group-fed RAC and subjected to withdrawal 2, 4, or 7 days before harvest. Ractopamine (parent and total) residues were below the assay limit of detection (< 0.12 ng/g) in all muscle and adipose tissue samples from animals in control groups (no RAC). However, RAC residues were detectable, but below the limit of quantitation, in 40% of tallow and 17% of large intestine samples from control animals. As expected, mean RAC residue concentrations in muscle, adipose tissue, and large intestine samples decreased (P < 0.05) as the RAC withdrawal duration (days) was extended. Irrespective of RAC withdrawal duration, mean parent RAC residue concentrations in muscle, adipose tissue, and large intestine ranged from 0.33 to 0.76 ng/g, 0.16 to 0.26 ng/g, 3.97 to 7.44 ng/g, respectively and all tallow samples were > 0.14 ng/g (detectable but below the limit of quantitation). Results of this study provide a baseline for the development of management protocol recommendations associated with withdrawal following group-feeding of RAC to beef cattle in countries that allow RAC use and intend to export to global markets which may be subject to zero tolerance policies and off-target tissue testing.

PSVI-12 Effects of polyphenols (mixed tannins) and saponin (Yucca schidigera), with or without a direct fed microbial (DFM) on in vitro rumen fermentation

Rumen fluid from fistulated steers receiving a high concentrate diet was utilized to examine the impact of polyphenols and saponin with or without a direct fed microbial (DFM) on in vitro fermentation characteristics. Treatments consisted of: Control (no polyphenols, saponin or DFM); 2) Polyphenols (Mixed Tannins = 15 g/hd/d); 3) Saponin (Y. schidigera = 2 g/hd/d); 4) Polyphenols + DFM (DFM = 1E+7 Lactobacillus animalis + 1E+8 Propionibacteria acidilactici cfu/hd/d); and 5) Saponin + DFM. Rumen fluid was collected and combined in equal amounts from 3 rumen fistulated steers and mixed at a 1:1 ratio of artificial saliva to rumen fluid. Fermentation substrate consisted of 0.5 g of the high concentrate diet. Fermentation bottles were capped with an air-tight rubber stopper and incubated in a water bath for 12 and 18h (7 replicates/treatment/time point). After incubation, the total volume of gas produced was measured and a subsample analyzed for N, CH4 and CO2 concentrations. After gas sampling, pH, VFA concentrations, and DMD were determined. In vitro fermentation parameters were analyzed using a mixed effects model repeated measures analysis for a completely randomized block design. Acetic acid was decreased while valeric acid was increased (P &lt; 0.05) by the Saponin + DFM treatment vs. Control. At 12h DMD was greater in Saponin, Saponin + DFM and Polyphenols + DFM (P &lt; 0.001) treatments compared to Control or Polyphenols alone. Polyphenols produced greater amounts of CH4 /DMD than all other treatments (P &lt; 0.01). Microbial protein production and efficiency were greater (P &lt; 0.001), Saponin + DFM compared to other treatments. Other fermentation parameters measured were not impacted by treatments. Under the conditions of this experiment these data suggest combining DFM with Saponin or Polyphenols produces different ruminal effects from when they are fed alone.

393 Awardee Talk: Effect of trace mineral source on rumen fermentation and trace mineral distribution in the rumen

The role that Cu and Zn play in rumen microbial fermentation is not well understood. Microorganisms use small proportions of dietary Cu and Zn for catalytic, structural, and stabilizing functions. In order for microorganisms to acquire Cu and Zn, the elements must be soluble in the rumen environment. Data would indicate that practical diets fed to ruminants without Cu and Zn supplementation are able to meet the microbial Cu and Zn requirements. Therefore, rumen solubility of supplemental Cu and Zn can impact rumen microbial fermentation characteristics. Numerous factors can impact rumen solubility of minerals, such as the pH of the rumen, the concentration of dietary antagonists (Mo, Fe, S, fiber, etc.), and mineral source. Earlier research has indicated that high soluble concentrations of Cu and Zn in the rumen environment can become toxic to certain rumen microorganisms and decrease fiber digestion. Recent research from our laboratory has indicated that hydroxy trace mineral (HTM) forms of Cu and Zn are relatively insoluble in the rumen and that a greater proportion of HTM remained loosely bound to the insoluble fraction within the rumen when compared to sulfate trace mineral (STM) sources of Cu and Zn. We have also reported that supplemental sources of Cu and Zn that are highly soluble in the rumen environment (STM) can decrease fiber digestion, reduce total VFA concentrations, and can become more tightly bound to rumen solid digesta than HTM sources of Cu and Zn. The stronger binding of STM relative to HTM to the solid rumen digesta fraction may reduce absorption in the small intestine. Future research investigating the flow and passage rate of different trace mineral sources through the abomasum into the duodenum and duodenal absorption efficiency of Cu and Zn from different TM sources is needed.

PSVII-12 Investigating the influence of copper supplementation on copper homeostatic genes in bovine liver

The objective of this experiment was to investigate the influence of copper (Cu) supplementation on Cu homeostatic genes in bovine liver. Liver samples were obtained from multiparous cows (n = 3 cows per treatment) from a previous experiment. Treatments consisted of: 1) no supplemental Cu (-Cu; total diet contained 7.0 mg Cu/kg DM) and 2) 3 mg Cu/kg DM (+Cu; total diet contained 10.0 mg Cu/kg DM). Cows were fed their respective diets for 420 d. Liver samples were harvested immediately upon slaughter, rinsed with phosphate-buffered saline solution, diced into small pieces, and placed into RNAlater and frozen at -80°C. Total RNA was extracted from all samples, and quantitative RT-PCR was used to determine the abundance of transcripts for proteins involved in Cu homeostasis in liver tissue. The target transcripts were: ALDH2, APOA1, ATOX1, ATP7A, ATP7B, BHMT, BLVRB, CA2, CCS, COX17, CTR1, ELN, GAPDH, GLUD1, GSS, LOXL1, PDIA3, SOD1, SOD3. The relative abundance of APOA1, ATOX1, ATP7B, BLVRB, CTR1, GLUD1, LOXL1, and SOD3 mRNA was greater (P &lt; 0.05) in cows receiving supplemental Cu when compared to cattle not receiving supplemental Cu. These data indicate possible differences in Cu homeostasis in the liver based on Cu supplementation. Further investigation is warranted to determine if a difference in the relative abundance of identified transcripts are related to differences in associated protein production and function.

PSXII-14 The influence of trace minerals source on copper, manganese, and zinc binding strength to rumen digesta in cattle fed a corn silage-based diet

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 &lt; 0.05) in HTM vs. STM and ORG supplemented steers, and Mn concentrations were greater (P &lt; 0.05) in HTM and ORG vs. STM supplemented steers. At 24 h post dosing, IDF Zn concentrations were greater (P &lt; 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 &lt; 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.

PSVII-21 The impact of cell culture and copper dose on copper trafficking genes in bovine liver

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 &lt; 0.001), ATOX1 (P &lt; 0.01), PDIA3 (P &lt; 0.05). As Cu dose increased, the relative abundance of ALDH2 increased, and ATOX1 and PDIA3 decreased. Significant quadratic responses existed for ATP7B (P &lt; 0.001), COX17 (P &lt; 0.05), and SOD1 (P &lt; 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.

PSXII-13 The influence of trace mineral source on copper, manganese, and zinc binding strength to rumen digesta in cattle fed a high forage-based diet

Twelve crossbred Angus steers fitted with rumen cannulae were used to determine the influence of trace mineral source on ruminal soluble mineral concentrations and relative binding strength of trace minerals in the ruminal insoluble digesta fraction. Steers were adjusted to a low-quality hay (chopped) diet balanced to meet the nutrient requirements for growing steers. For 7 d prior to initiation of the study, steers were fed the diet without supplemental Cu, Mn, and Zn. On day 8 steers received a pulse dose (2 x NRC requirement) of Cu, Mn, and, Zn from sulfate (STM) or hydroxy trace minerals (HTM; Micronutrients LLC, USA). Ruminal samples were obtained at 2 h intervals until 24 h post-dosing for soluble (fraction obtained after centrifugation) Cu, Mn, and Zn concentrations. Binding strength of Cu, Mn, and Zn to ruminal solid digesta (post centrifugation) was estimated at 0, 12, and 24h post-dosing using dialysis against 0.05 M Tris-EDTA. Ruminal soluble mineral concentrations were greater (P &lt; 0.05) for Cu at 4, 6, 8, 10, 12, and 16 h; for Mn at 4 and 6 h; and for Zn at 4, 6, and 8 h post dosing in STM compared to HTM steers. Concentration of Cu, Mn, and Zn remaining in the insoluble fraction were greater (P &lt; 0.05) at 12 h post dosing in HTM vs STM supplemented steers. At 24 h post dosing, Mn concentrations were lesser (P &lt; 0.03) and Zn concentrations were greater (P &lt; 0.001) in HTM vs STM supplemented steers. Following dialysis, the % Cu, and Zn released from the insoluble fraction was greater (P &lt; 0.001) at 12 h and 24h in HTM vs. STM supplemented steers. Results indicate that a greater proportion of Cu and Zn HTM remained loosely bound to the insoluble fraction within the rumen.

PSXII-12 The influence of long-term molybdenum supplementation (in drinking water or feed) on beef calf performance through weaning

Fifty-four multiparous beef cows were used to examine the effect of molybdenum (Mo) supplemented in drinking water or feed on offspring performance. Cows were blocked by body weight (BW) and age into one of 6 groups. Group were then randomly assigned to treatment. Treatments consisted of: 1) Control (no supplemental Mo or Cu), 2) Control+Cu (3 mg Cu/kg DM from CuSO4·5H2O added to the basal diet), 3) Control + 500 µg Mo/L from MoNa2O4·2H2O in drinking water (Mo 500-water), 4) Control + 1000 µg Mo/L of MoNa2O4·2H2O in drinking water (Mo 1000-water), 5) Mo 1000-water plus 3 mg Cu/kg DM from CuSO4·5H2O added to the basal diet (Mo 1000-water+Cu, and 6) Control plus 3 mg Mo/kg DM from MoNa2O4·2H2O added to the basal diet (3.0 Mo-diet). Cows were housed in dry lot pens (n = 3 cows/pen; 3 pens/treatment) and fed a low-quality grass hay diet (DM basis: 6.6% CP; 0.14% S, 6.2 mg Cu/kg, 2.3 mg Mo/kg) and a protein supplement (30% CP). Cows received their respective treatments beginning 60 d prior to breeding and remained on treatments until all calves were weaned at approximately 7 mo. of age. Calf birth weights were collected on the day of birth and all calves were weaned on the same day. Data were analyzed using a mixed effects model for a completely randomized block design. Birthweight, ADG, and 205d adjusted weaning weights were similar (P &gt; 0.05) across treatments. These data indicate that Mo supplemented in the drinking water or the diet regardless of the inclusion of additional Cu did not impact calf performance through weaning.

Trace mineral source influences ruminal distribution of copper and zinc and their binding strength to ruminal digesta1,2,3

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.

Prediction of water intake to Bos indicus beef cattle raised under tropical conditions1

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 × TMAX -0.259 × HU + 0.489 × DMI, where the MBW is the metabolic BW (kg0.75), TMAX 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.

Effect of zinc source and concentration and chromium supplementation on performance and carcass characteristics in feedlot steers1,2,3

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.

Determination of macromineral requirements for preweaned dairy calves in tropical conditions

International committees that have published nutrient requirements for dairy cattle have used data from mineral studies conducted in the 1920s to 1970s, and no study has reported data from animals less than 100 kg; therefore, there is a need to update mineral requirements for preweaned dairy calves. Thus, a meta-analysis was performed to estimate the mineral requirements of Ca, P, K, Mg, and Na for Holstein and Holstein × Gyr crossbred preweaned dairy calves using data from 5 studies developed at the Universidade Federal de Viçosa (Viçosa, MG, Brazil). A total of 210 calves were separated into 2 breeds: purebred Holstein calves (animals with a Holstein pedigree higher than 87.5%) and Holstein × Gyr crossbred calves (animals with a Holstein pedigree lower than 87.5%). The comparative slaughter technique was used to estimate animal body composition and empty body weight (EBW). Mineral requirements for maintenance were estimated by the regression between retained mineral and mineral intake, whereas mineral requirements for gain were obtained from the first derivative of the mineral content in the animal's body. In addition, breed effect was tested on the intercept and slope of the models. The effect of breed was not observed for all analyzed variables. Thus, net requirements for maintenance were 12.73, 11.81, 20.28, 3.50, and 6.37 mg/kg of EBW per day for Ca, P, K, Mg, and Na, respectively. Retention coefficients were 73.18, 65.20, 13.16, 29.55, and 24.28% for Ca, P, K, Mg, and Na, respectively. The following equations were determined to estimate net requirements for gain (NRG, g/d): NRG for Ca = 14.402 × EBW^-0.139 × empty body gain (EBG); NRG for P = 5.849 × EBW^-0.027 × EBG; NRG for K = 1.140 × EBW^-0.048 × EBG; NRG for Mg = 0.603 × EBW^-0.036 × EBG; and NRG for Na = 1.508 × EBW^-0.045 × EBG. Due to the high variation between the data found in this study and in the available literature, we suggest that further studies should be conducted to evaluate the estimates of this study.

Special-Fed Veal: Separable components, proximate composition, and nutrient analysis of selected raw and cooked, wholesale and retail cuts

Nutrition research continues to be important for consumers to make informed food purchasing decisions and is used in nutrition policy decisions. The objective of this study was to analyze the nutrient concentration of raw and cooked cuts from special-fed veal calves to update nutrient data in the USDA National Nutrient Database for Standard Reference (SR) Release 27. Packages of wholesale (whole loin roasts, center-cut hindshanks and ground veal) and retail veal cuts (osso buco foreshanks, loin chops, leg cutlets and shoulder blade chops) were randomly collected in original vacuum packaging from six U.S. suppliers. Packages were shipped to the Colorado State University Meat Laboratory for cut dissection, cooking, and nutrient analysis. Composites of lean, external fat and seam fat were formed for analysis of proximate, fatty acid, vitamin and mineral composition. Results from this study identified additional fatty acids, established choline concentration, and provided updated veal nutrient composition information for inclusion in USDA SR 27.

Palatability Characterization of Fresh and Dry-Aged Ground Beef Patties

Descriptive trained sensory attributes, fatty acids, and volatile compounds were determined to characterize the effects of dry-aging on ground beef. Beef shoulder clods were ground to include 100% fresh beef, 100% dry-aged beef, and a 50% fresh and 50% dry-aged ground beef blend. Samples comprised of 100% dry-aged beef were rated greatest (P < 0.001) for browned/grilled, earthy/mushroom, and nutty/roasted-nut flavors; however, panelists also detected greater (P ≤ 0.011) incidences of sour/acidic and bitter flavors. The addition of dry-aged beef increased (P < 0.001) hardness and reduced (P < 0.001) tenderness. Dry-aging also caused a shift in saturated fatty acids, where shorter chain saturated fatty acids (≤ 16:0) were reduced (P ≤ 0.034) compared to stearic acid (18:0). Meanwhile, increases of trans-octadecenoic acid (18:1 trans) and decreases of cis monounsaturated fatty acids were present in dry-aged beef. Concentrations of 18:2 conjugated linoleic isomers were greatest (P < 0.001) in fresh beef and decreased with the incorporation of dry-aged beef. Several lipid-derived volatile compounds were greater (P < 0.05) in dry-aged beef compared with fresh beef, implying a greater degree of lipid degradation among dry-aged beef. Increases (P ≤ 0.031) were determined for 3- and 2-methyl butanal with the addition of dry-aged beef. Intermediates of the Maillard reaction, 2,3-butanedione and acetoin, were determined to be greatest (P ≤ 0.046) from dry-aged beef. Alterations of fatty acids and volatile compounds with dry-aging were determined to be related with intensity of individual flavor attributes. Overall, it may be concluded that inclusion of dry-aged beef impacts flavor profile through altered fatty acid profiles and flavor related compounds. These results support the idea that dry-aging may be utilized to impart an altered ground beef flavor experience.

Effect of fish meal supplementation on luteal sensitivity to intrauterine infusions of prostaglandin F2α in the bovine

Progesterone is a steroid hormone secreted from the corpus luteum (CL), which is responsible for establishment and maintenance of pregnancy. Early embryonic mortality often occurs due to inadequate regulation of uterine prostaglandin (PG) F2α secretion, leading to a decrease in progesterone and loss of pregnancy. The objective of the current study was to determine the effects of fish meal supplementation on luteal sensitivity to intrauterine infusions of PGF2α. Nonlactating beef cows received corn gluten meal or fish meal supplementation for 60 days. Cows were administered four intrauterine infusions of 0.25 mL saline at 6-h intervals (n = 6 corn gluten meal; n = 5 fish meal) or two doses of 0.5 mg PGF2α in 0.25 mL saline at 12-h intervals (n = 11 corn gluten meal; n = 11 fish meal) commencing on days 10 to 12 of the estrous cycle. At time of each infusion, luteal biopsies were collected to determine the effects of supplementation on expression of immediate early and steroidogenic genes involved in cholesterol transport and progesterone biosynthesis. Transrectal ultrasonography was performed to measure diameter of CL, and blood samples were collected to determine serum progesterone. Intrauterine infusion of PGF2α resulted in upregulation or no change in FOS, NR4A1, and 3BHSD and downregulation in LDLR, STARD1, and CYP11A1. Although CL diameter decreased, infusion of PGF2α resulted in functional regression in 91% of cows supplemented with corn gluten meal, and only 46% for fish meal supplemented animals. Results demonstrate that fish meal supplementation alters luteal sensitivity to PGF2α, which may affect fertility.

The effects of molybdenum water concentration on feedlot performance, tissue mineral concentrations, and carcass quality of feedlot steers,

Thirty cross-bred steers (initial BW 452.0 ± 12.1 kg) were used to investigate the effects of Mo water concentration on performance, carcass characteristics, and mineral status of feedlot steers. The experimental design was a randomized complete block design. Steers were blocked by weight and then divided into 2 weight blocks each consisting of 15 steers. Steers were randomly assigned within block to one of 5 treatments (3 steers/treatment per block). Water treatments consisted of: 1) 0.0 µg/L, 2) 160 µg/L, 3) 320 µg/L, 4) 480 µg/L, and 5) 960 µg/L of supplemental Mo added as Na2MoO4 to the drinking water. Steers were housed in individual pens (steer = experimental unit) that contained individual 265 L water tanks for monitoring water intake. Steers were fed a growing diet for 28 d and then transitioned to a finishing diet. Block 1 steers were fed for a total of 151 d and block 2 steers were fed for a total of 112 d. Daily water intake was recorded for each steer. Steers were individually weighed on 2 consecutive days at the beginning and end of the experiment and interim weights and jugular blood samples were obtained every 28 d. Liver biopsies were obtained on d 0 and 84 from each steer within each block. Steers were transported to a commercial abattoir, slaughtered, and individual carcass data and liver samples were collected. Initial BW was used as a covariate for statistical analysis of data and significance was determined at P ≤ 0.05. No differences were observed for final BW (P > 0.98). Overall ADG (P > 0.91), DMI (P > 0.92), feed efficiency (P > 0.94), water intake (P > 0.40), hot carcass weight (P > 0.98), dressing percentage (P > 0.98), yield grade (P > 0.91), and marbling score (P > 0.29) did not differ across treatments. Lastly, no treatment differences were observed for liver concentrations of Cu (P > 0.93), Mo (P > 0.90) and Zn (P > 0.86) or plasma concentrations of Cu (P > 0.42), Mo (P > 0.43) and Zn (P > 0.62). These data indicate that water Mo concentration, within the range studied, had no impact on performance, mineral status, water intake, and carcass characteristics in feedlot steers.

Nutritional depletion of total mixed rations by European starlings: Projected effects on dairy cow performance and potential intervention strategies to mitigate damage

European starlings are an invasive bird species in North America that are known to cause damage to commercial dairies through the consumption of total mixed rations (TMR) destined for dairy cows. We hypothesized that large foraging flocks of starlings alter the physical composition of TMR, and that this change may be significant enough to affect milk production. To better determine if production losses could potentially occur in commercial dairies as a consequence of feed consumption by foraging flocks of starlings, we conducted controlled feeding experiments using a TMR sourced from a commercial dairy that is chronically plagued with seasonal starling damage. European starlings selected the high-energy fraction of the TMR and reduced starch and crude fat availability. Using the dairy National Research Council production model equations, the nutritional changes measured in the controlled feeding experiments could potentially reduce the productivity of dairies. Model output suggests that for Holsteins producing 32 kg of milk/d, total required net energy intake (NE_I) was 31.5 Mcal/d. Within the reference TMR, NE_I supplied was 29.3 Mcal/d, whereas within the starling-consumed TMR NE_I supplied was 27.7 Mcal/d. Following our nutrition experiments, we assessed the efficacy of pelleted feed as a deterrent strategy for bird damage management in commercial dairies. Six different pelleted feed treatments of differing diameter were offered to starlings. All pellets of 0.95 cm diameter or larger inhibited starling consumption by ≥79%.

Effect of fish meal supplementation on spatial distribution of lipid microdomains and on the lateral mobility of membrane-bound prostaglandin F2α receptors in bovine corpora lutea

This study examined the effects of fish meal supplementation on spatial distribution of lipid microdomains and lateral mobility of prostaglandin F_2α (FP) receptors on cell plasma membranes of the bovine corpus luteum (CL). Beef cows were stratified by BW and randomly assigned to receive a corn gluten meal supplement (n = 4) or fish meal supplement (n = 4) for 60 d to allow incorporation of fish meal-derived omega-3 fatty acids into luteal tissue. Ovaries bearing the CL were surgically removed between days 10 to 12 after estrus corresponding to approximately day 60 of supplementation. A 200-mg sample of luteal tissue was analyzed for fatty acid content using gas-liquid chromatography (GLC). The remaining tissue was enzymatically digested with collagenase to dissociate individual cells from the tissue. Cells were cultured to determine the effects of dietary supplementation on lipid microdomains and lateral mobility of FP receptors. Luteal tissue collected from fish meal-supplemented cows had increased omega-3 fatty acids content (P < 0.05). Lipid microdomain total fluorescent intensity was decreased in dissociated luteal cells from fish meal-supplemented cows (P < 0.05). Micro and macro diffusion coefficients of FP receptors were greater for cells obtained from fish meal-supplemented cows (P < 0.05). In addition, compartment diameter of domains was larger, whereas resident time was shorter for receptors from cells obtained from fish meal-supplemented cows (P < 0.05). Data indicate that dietary supplementation with fish meal increases omega-3 fatty acid content in luteal tissue causing disruption of lipid microdomains. This disruption leads to increased lateral mobility of the FP receptor, increased compartment sizes, and decreased resident time, which may influence prostaglandin signaling in the bovine CL.

Estimating mineral requirements of Nellore beef bulls fed with or without inorganic mineral supplementation and the influence on mineral balance

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.

Duration of maternal undernutrition differentially alters fetal growth and hormone concentrations

To investigate the impact of duration of maternal undernutrition in twin sheep pregnancies, ewes were either fed 100% (C) or 50% of their nutrient requirements from 28 to 78 d gestational age (dGA) and readjusted to 100% beginning at 79 dGA (LC) or continuously restricted from 28 to 135 dGA (LL). Weights of the fetus, empty carcass, brain, and liver were greater in the LC than LL fetuses at 135 dGA (P ≤ 0.05). Although umbilical vein (UmV) glucose concentrations did not differ, the UmV:umbilical artery (UmA) glucose gradient was smaller (0.26 ± 0.03 vs 0.38 ± 0.03 and 0.39 ± 0.04 mmol L(-1); P ≤ 0.05) in LL than C and LC fetuses, respectively. Umbilical vein concentrations of IGF-1 were less (46.7 ± 5.62 vs 74.3 ± 6.71 ng/mL; P ≤ 0.05) in LL than LC fetuses. Additionally, LL fetuses tended (P ≤ 0.10) to have lower UmA concentrations of insulin (0.24 ± 0.13 vs 0.70 ± 0.15 ng/mL) and IGF-1 (66.6 ± 7.51 vs 91.4 ± 8.97 ng/mL) than LC fetuses. Although most of the observed differences occurred between LC and LL pregnancies, LC fetuses tended (P ≤ 0.10) to have greater UmV and UmA pCO2 than C fetuses. Furthermore, the UmV:UmA O2 content gradient tended to be greater (5.02 ± 0.43 vs 3.41 ± 0.47; P ≤ 0.10) in C than LL fetuses. UmA placental lactogen also tended to be greater (46.6 ± 4.40 vs 31.1 ± 4.69 ng/mL; P ≤ 0.10) in LL than C fetuses. These data suggest that in twin pregnancies, maternal undernutrition followed by realimentation induces a different fetal outcome compared with continuous nutrient restriction, and both may differ physiologically from control fed pregnancies.

Effects of day of gestation and feeding regimen in Holstein × Gyr cows: III. Placental adaptations and placentome gene expression

This study investigated the influence of day of gestation (DG) and feeding regimens (FR) on the expression of genes responsible for placenta development, nutrient transfer, and angiogenic factors in Holstein × Gyr cows. Forty pregnant multiparous Holstein × Gyr cows with an average initial body weight of 482±10.8kg and an initial age of 5±0.8 yr were allocated to 1 of 2 FR: ad libitum (AL; n=20) or maintenance level (ML; n=20). Maintenance level was considered to be 1.15% of body weight (dry matter basis) and met 100% of the net energy requirements and AL provided 190% of the total net energy requirements. Cows were slaughtered at 4 DG: 139, 199, 241, and 268d. After the cows were slaughtered, the placenta and uterus were separated and weighed. Caruncles and cotyledons were individually separated, counted, and weighed. Placenta expressed as kilograms and grams per kilogram of empty body weight (EBW) was heavier in ML- than in AL-fed cows at 268d of gestation. Placenta expressed as kilograms and grams per kilogram of EBW was the lightest at 139d of gestation, and the greatest mass was observed at 268d in ML-fed cows. However, in AL-fed cows, the heaviest placenta expressed as grams per kilogram of EBW was observed from 199d of gestation. Placentomes expressed as grams per kilogram of EBW were heavier in ML-fed cows during gestation, and the number of placentomes was greater in ML-fed cows at 268d of gestation. We observed that IGFR1 and IGFR2 were involved in placenta adaptations when ML was provided, as their expression in placentome cells was greater in ML-fed cows at 268d of gestation. The genes responsible for angiogenesis were also greater in ML-fed cows: VEGFA, GUCY1B3, HIFA, FGF2, and NOS3 were altered by FR and DG interaction and they were greater in ML-fed cows at 268d of gestation. In addition, VEGFB and ANGPT2 did not show interactions between FR and DG, but they were greater in ML-fed cows. Thus, we suggest that the placenta from an ML-fed cow develops adaptations to the reduced nutrient supply by altering its structure and gene expression, thereby developing mechanisms for potential increased nutrient transfer efficiency to the fetus.

The impact of dietary sugarcane addition to finishing diets on performance, apparent digestibility, and fatty acid composition of Holstein × Zebu bulls

The objective of this study was to evaluate the influence of corn silage (CS) or sugarcane (SC) additions to finishing diets on voluntary intake, apparent digestibility, animal performance, and LM fatty acid (FA) composition in crossbred Holstein × Zebu bulls. Forty-two bulls (initial BW 328 ± 39.2 kg and an initial age of 23.5 mo) were used in this experiment. A completely randomized design was used to examine roughage source (CS vs. SC) and ratio of concentrate (CO) on nutrient utilization and production. The experimental diets consisted of 1) 60% CS and 40% CO on DM basis fed for 84 d (CS60:40), 2) 60% CS and 40% CO on DM basis fed for 42 d and 40% CS and 60% CO on DM basis fed for 42 d (CS reverse diet [CSR]), 3) 40% CS and 60% CO on DM basis fed for 84 d (CS40:60), 4) 60% SC and 40% CO on DM basis fed for 84 d (SC60:40), 5) 60% SC and 40% CO on DM basis fed for 42 d and 40% SC and 60% CO on DM basis fed for 42 d (SC reverse diet [SCR]), and 6) 40% SC and 60% CO on DM basis fed for 84 d (SC40:60). Dry matter and NDF intakes were greater (P < 0.01) in bulls fed CS-based diets than bulls fed SC-based diets. The greatest (P < 0.01) DM and CP digestibility were observed in bulls fed SC-based diets. Bulls fed CSR and CS40:60 had greater (P < 0.01) ADG than bulls fed SC-based diets. However, ADG was similar (P = 0.52) in bulls fed CS60:40, CSR, and SC40:60 diets. The percentage of C18:3 n-3 and C20:5 n-3 were greater (P < 0.01) in LM of bulls fed SC-based diets. The percentage of CLA was greater (P < 0.01) in LM of bulls fed SC60:40 than those fed CS-based diets. The findings of the present study indicate that SC40:60 can replace CS60:40 and CSR in finishing diets and, moreover, roughage source significantly altered the FA composition of crossbred Holstein × Zebu bulls LM.

Nutrient database improvement project: the influence of USDA quality and yield grade on the separable components and proximate composition of raw and cooked retail cuts from the beef chuck

This study was designed to provide updated information on the separable components, cooking yields, and proximate composition of retail cuts from the beef chuck. Additionally, the impact the United States Department of Agriculture (USDA) Quality and Yield Grade may have on such factors was investigated. Ultimately, these data will be used in the USDA - Nutrient Data Laboratory's (NDL) National Nutrient Database for Standard Reference (SR). To represent the current United States beef supply, seventy-two carcasses were selected from six regions of the country based on USDA Yield Grade, USDA Quality Grade, gender, and genetic type. Whole beef chuck primals from selected carcasses were shipped to three university laboratories for subsequent retail cut fabrication, raw and cooked cut dissection, and proximate analyses. The incorporation of these data into the SR will improve dietary education, product labeling, and other applications both domestically and abroad, thus emphasizing the importance of accurate and relevant beef nutrient data.

Effects of pain mitigation and method of castration on behavior and feedlot performance in cull beef bulls

The objectives of this study were to evaluate the effects of castration method (banding vs. surgical) and use of analgesia on behavior and feedlot performance in cull bulls. Angus, Hereford, and Angus-crossbred bulls (n = 20; initial BW = 384 ± 59.3 kg; 336 ± 20.1 d old) were housed in feedlot pens equipped with the ability to measure individual daily feed intake. A balanced randomized block design using a 2 × 2 factorial arrangement of treatments was used. A multimodal analgesia (MMA) protocol was used and consisted of sutcutaneous ketamine stun containing butorphanol (0.01 mg/kg BW), xylazine (0.02 mg/kg BW), ketamine (0.04 mg/kg BW), and a local 2% lidocaine hydrochloride anesthetic block of the spermatic cords (10 mL/cord) and scrotum (10 mL) on d 0. Flunixin meglumine (1.2 mg/kg) was administered intravenously on d 0, 1, 2, and 3 to MMA cattle. Cattle were stratified to treatments based on breed, BW, age, and a temperament score. Treatments included 1) band castration without analgesia (BND), 2) band castration with analgesia (BND-MMA), 3) surgical castration without analgesia (SURG), and 4) surgical castration with analgesia (SURG-MMA). All castrations were performed on d 0. Chute exit velocity (EV) and time in chute (TIC) were collected on d -9, 0, 1, 2, and 13. Willingness-to-enter-chute (WTE) score, rectal temperature (TEMP), heart rate (HR), and respiration (RESP) were collected on d 0, 1, 2, 3, and 13. Cattle were weighed on d -9 and 13 while feeding behaviors were collected continuously for 57 d precastration and 28 d postcastration. There was a tendency (P < 0.09) for ADG to be greater in cattle receiving analgesia. Both SURG treatments exhibited elevated TEMP on d 1 (P < 0.001) and 2 (P < 0.05) compared to BND treatments. Postcastration DMI was greater (P = 0.02) in MMA treatments compared with nonmedicated treatments throughout the trial. Meal duration was greater (P < 0.05) in BND than SURG castrates during the first week postcastration. Results suggest that pain mitigation reduces the impact of castration on ADG and DMI.

Impact of oral meloxicam administration before and after band castration on feedlot performance and behavioral response in weanling beef bulls

Two experiments evaluated the effects of band castration and oral administration of an analgesic 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 procedures 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, jugular 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 administration. 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 similar 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 performance or behavioral and physiological responses to band castration. However, there was a negative impact of castration on ADG and DIST.