Bedding Application and Increasing Dosage of Trenbolone Acetate and Estradiol in Implants for Beef Steers: Influence on Growth Performance, Carcass Characteristics, and Circulating Metabolite Responses

Three randomized complete block design feedlot experiments were conducted over the course of two years. Two experiments were conducted to investigate the effect of bedding use in confined beef steers. The third experiment evaluated the effects of implants containing increasing doses of trenbolone acetate (TBA) and estradiol benzoate (EB) in confined beef steers. Experiment 1 used Simmental × Angus steers (n = 240; initial body weight (BW) = 365 ± 22.5 kg). Experiment 2 used newly weaned Charolais × Red Angus steers (n = 162; initial BW = 278 ± 13.4 kg). Steers were allotted to 1 of 2 treatments: 1) no bedding (NO), or 2) 1.8 kg (Exp. 1) or 1.0 kg (Exp. 2) of wheat straw (as-is basis) bedding/steer·d-1 (BED). In Exp. 1 and Exp. 2 data were analyzed as a randomized complete block design with pen serving as the experimental unit for all analyses. In Exp.1, applying bedding improved (P ≤ 0.01) dry matter intake (DMI), gain:feed (G:F), and average daily gain (ADG). Bedding reduced (P = 0.01) the estimated maintenance coefficient (MQ). Dressing percentage, rib fat, marbling, and yield grade were increased (P ≤ 0.03) in NO. Bedding resulted in an increase (P = 0.01) in serum insulin-like growth factor I (IGF-I). In Exp. 2, a tendency (P = 0.06) for increased DMI for NO was noted. Bedding improved G:F (P = 0.01). MQ was elevated (P = 0.03) for NO and NO had an increase (P = 0.02) in serum concentration of urea-N (SUN). An increase (P = 0.01) in serum non-esterified fatty acid was noted for NO. These data indicate that bedding application should be considered to improve growth performance and feed efficiency by reducing maintenance energy requirements in beef steers during the feedlot receiving and finishing phase. In experiment 3, yearling Simmental × Angus crossbred beef steers (n = 240; allotment BW = 365 ± 22.5 kg) from a South Dakota auction facility were transported 117 km to Brookings, SD and used in a randomized complete block design feedlot study to evaluate the effects of implants (both from Zoetis, Parsippany, NJ) containing increasing doses of TBA and EB administered 124 d prior to harvest have on finishing phase growth performance, carcass characteristics, and serum concentrations of urea-N (SUN) and insulin-like growth factor I (IGF-I). Thirty pens (10 pens/treatment) were assigned to 1 of 3 treatments: 1) negative control given no implant (NI); 2) a steroidal implant containing 100 mg TBA and 14 mg EB administered subcutaneously in the center one-third of the ear on d 1 (Synovex Choice, Zoetis, Parsippany, NJ; CH); 3) a steroidal implant containing 200 mg TBA and 28 mg EB administered subcutaneously in the center one-third of the ear on d 1 (Synovex Plus, Zoetis; PL). Cattle were fed for 124 d post-implantation. Steers were fed a common diet throughout the study. Treatment effects were evaluated by the use of orthogonal polynomials. Pen was the experimental unit for all analyses; an α of 0.05 determined significance. There was a quadratic effect (P = 0.01) on carcass adjusted final BW. Increasing doses of TBA and EB resulted in a linear increase for both ADG (P = 0.01) and DMI (P = 0.02). A quadratic effect on G:F was observed (P = 0.01). No quadratic (P ≥ 0.40) or linear (P ≥ 0.14) effects were observed for dressing percentage, rib fat (RF), calculated yield grade, or marbling scores. A quadratic increase (P = 0.01) in hot carcass weight (HCW) and a linear increase (P = 0.01) in ribeye area (REA) was detected. No significant implant × day interaction (P ≥ 0.09) was noted for serum concentrations of urea-N or IGF-I. Implants decreased (P = 0.01) circulating SUN compared to NI. Serum concentration of IGF-I was increased (P = 0.04) in implanted steers compared to NI steers. In yearling crossbred beef steers the use of steroidal implants containing a combination of 100 mg TBA + 14 mg EB or 200 mg TBA + 28 mg EB increases growth performance, HCW, and REA at equal RF accumulation without detriment to marbling score compared to non-implanted steers

Effects of Lubabegron supplementation on carcass traits, muscle fiber type, proteome profile and meat quality attributes of finished feedlot steers

2020 Spring.Includes bibliographical references.Two thousand one hundred and sixty (2,160) British and Continental crossbred steers were supplemented (1, 4, 3.2 or 5.0 g/ton (DM basis) Lubabegron and a control diet (Experior; EX, Elanco Animal Health) for the last 28, 56, or 84 d of the finishing period resulting in twelve treatment combinations. Fifteen pens (12 hd/pen) were allocated to each treatment combination consisting of a dose and feeding duration. A total of five harvest cycles were conducted, consisting of 432 head per cycle. Each harvest cycle consisted of 3 blocks, each block contained all dosages and each block was associated with a specific feeding duration. Hot carcass weights (HCW), marbling scores (MS), adjusted fat thickness (aFT), longissimus muscle area (LMA), kidney pelvic and heart fat percentage (KPH), and USDA calculated yield grade (YG) were evaluated for all carcasses (N = 2160). No dose x feeding duration (FD) interaction (P > 0.05) was present for any of the characteristics measured. Supplemented cattle produced heavier (P 0.05) were observed for muscle fiber type as it relates to meat quality. The muscle fiber type IIX cross sectional area remained similar across the majority of treatment groups, except for decrease in CSA seen in cattle fed 5.0 g/ton for the final 56 and 84 d of feed. Meat quality attributes were measured using trained sensory panels, slice shear force (SSF) and Warner-Bratlzer shear force (WBSF). Striploins from the right side of each carcass were collected, fabricated into 2.54-cm steaks, and aged for 0, 7, 14, 21, and 28 d postmortem. Steaks for all postmortem aging periods were evaluated using SSF and WBSF, whereas, only those aged for 14 d were evaluated by trained panelists. Non- supplemented cattle produced striploin steaks that were juicier and more tender (P 0.05) were observed as a consequence of FD. All steaks (supplemented and non-supplemented) subjected to a minimum 7 d of PM aging produced WBSF that were less than 3.9 kg, and therefore eligible to be labeled as "Certified Very Tender." Once 21 d of postmortem aging was reached, no differences (P > 0.05) in tenderness were observed between the treatments. Based on meat quality attributes, six samples each (N = 24, n = 6) from four treatments (control, low dose for 28 days, high dose for 28 days, and high dose for 84 days) were selected for proteome analysis using a chemical labelling approach know as tandem mass tag (TMT). Experior supplementation influenced expression of proteins involved in muscle contraction, calcium signaling, transport, growth factor, and proteasome activation. Myosin light chain 3 (MYL3) was associated with an improved tenderness and carcass grading, which could be reflective of the increased intramuscular fat content. The proteins identified such as hemoglobin subunit α (HBA), hemoglobin subunit β (HBB), and alpha-1-acid glycoprotein (ORM1) were suggestive of increased vascularization in muscles as a response to EX supplementation

Essential oil effects on rumen fermentation, animal performance, and meat quality of beef steers

"December 2013.""A Thesis presented to the Faculty of the Graduate School University of Missouri--Columbia In Partial Fulfillment of the Requirements for the Degree Master of Science."Thesis advisors: Dr. Monty S. Kerley and Dr. Bryon Wiegand.Efficiency in ruminants has historically been improved by using antibiotics and ionophores to alter rumen fermentation. Nutritionists, however, have begun searching for alternative rumen modifiers due to the negative attention received by non-therapeutic antibiotic use. Plant extracts, like essential oils, are being explored as a potential alternative to alter fermentation and improve growth and efficiency in ruminants. Essential oils are naturally occurring, secondary metabolites that can be distilled or extracted from most plants and possess antimicrobial properties. Next Enhance® (NE, Novus International Inc.) is comprised of garlic (diallyl disulfide) and cinnamon (cinnamaldehyde) extracts; both have demonstrated the ability to modify fermentation. A series of experiments was conducted to determine how feeding NE affects in vitro fermentation, site and extent of nutrient digestion, feedlot performance, carcass traits, meat quality, and consumer sensory characteristics of LM steaks from beef steers. The first experiment in this thesis examined how feedlot steer performance and carcass traits were affected by NE feeding. ADG and G:F were improved early in the feeding period by 150 mg·hd-1 ·d-1 targeted NE inclusion. DMI, overall ADG, and overall G:F were not affected by NE inclusion. All NE levels improved dressing percent, 12th rib backfat, LM area, and calculated USDA yield grade. Steers fed 150 mg·hd-1 ·d-1 NE yielded carcasses worth nearly $30 more than control steers. LM steaks were obtained from five head/treatment and used to evaluate meat quality and consumer sensory characteristics. L*, a*, and b* color values were not affected by TRT on d 0 or 14. Cook loss percent was increased when low NE levels were fed but decreased by high NE doses. Warner-Bratzler shear force, and percent drip loss, moisture, and fat were not affected by NE inclusion. A consumer sensory panel reported no difference in beef steer LM steak organoleptic properties due to NE. NE inclusion at 150-300 mgIncludes bibliographical references (pages 73-80)

EVALUATION OF THE METABOLIC RESPONSE, BLOOD CHEMISTRY PROFILE, AND CARDIAC MORPHOLOGY OF BEEF HEIFERS SUPPLEMENTED WITH ZILPATEROL HYDROCHLORIDE FOLLOWED BY AN ENDOCRINE INDUCED STRESS CHALLENGE

The objective of this study was to determine the metabolic, stress, hematology, organ weights, histology and cardiac anatomical features of beef heifers supplemented with zilpaterol hydrochloride (ZH) when exposed to a corticotropin-releasing hormone (CRH) and arginine vasopressin (VP) challenge. Crossbred heifers (n = 20; 556 ± 7 kg BW) were randomized into two treatment groups: 1) Control (CON): no ZH, and 2) Zilpaterol (ZIL): supplemented with ZH at 8.33 mg / kg (DM basis). The ZIL group was supplemented ZH for 20 d, with a 3-d withdrawal period. On d 24, heifers received an intravenous bolus of CRH (0.3 µg / kg BW) and VP (1.0 µg / kg BW). Blood samples were collected at 30- and 60-min intervals for serum, and 60-min intervals for plasma and whole blood, from -2 to 8 h relative to the challenge. Heifers were harvested to collect organ weights and histology samples on d 25, 26, and 27. There was a treatment (P \u3c 0.001) effect for vaginal temperature (VT), with ZIL having a 0.1oC decrease in VT. A treatment x time effect (P = 0.002) was observed for non-esterified fatty acid such that concentrations were increased in CON heifers at 4, 6, 7, 7.5, and 8 hrs. There was a treatment effect for cortisol (P \u3c 0.01) and epinephrine (P = 0.003) with ZIL having decreased concentrations. Glucose concentrations within the longissimus muscle were greater (P = 0.03) in CON heifers. Lactate concentrations and glycolytic potential within the biceps femoris were greater in CON heifers (P = 0.05). A treatment effect (P ≤ 0.02) was observed for calcium and potassium, with ZIL heifers having decreased concentrations. Zilpaterol heifers had increased concentrations of creatinine (P = 0.02). A treatment x time interaction (P = 0.02) was observed for phosphorus. Raw liver weights tended (P = 0.08) to be less in ZIL heifers. These data suggest some variations between treatments in terms of response to ZH supplementation and challenge; however, in the environmental conditions of this study, the data suggests that the supplementation of ZH does not negatively alter the status of homeostasis in cattle. Advisor: Ty B. Schmid

EVALUATION OF THE METABOLIC RESPONSE, BLOOD CHEMISTRY PROFILE, AND CARDIAC MORPHOLOGY OF BEEF HEIFERS SUPPLEMENTED WITH ZILPATEROL HYDROCHLORIDE FOLLOWED BY AN ENDOCRINE INDUCED STRESS CHALLENGE

The objective of this study was to determine the metabolic, stress, hematology, organ weights, histology and cardiac anatomical features of beef heifers supplemented with zilpaterol hydrochloride (ZH) when exposed to a corticotropin-releasing hormone (CRH) and arginine vasopressin (VP) challenge. Crossbred heifers (n = 20; 556 ± 7 kg BW) were randomized into two treatment groups: 1) Control (CON): no ZH, and 2) Zilpaterol (ZIL): supplemented with ZH at 8.33 mg / kg (DM basis). The ZIL group was supplemented ZH for 20 d, with a 3-d withdrawal period. On d 24, heifers received an intravenous bolus of CRH (0.3 µg / kg BW) and VP (1.0 µg / kg BW). Blood samples were collected at 30- and 60-min intervals for serum, and 60-min intervals for plasma and whole blood, from -2 to 8 h relative to the challenge. Heifers were harvested to collect organ weights and histology samples on d 25, 26, and 27. There was a treatment (P \u3c 0.001) effect for vaginal temperature (VT), with ZIL having a 0.1oC decrease in VT. A treatment x time effect (P = 0.002) was observed for non-esterified fatty acid such that concentrations were increased in CON heifers at 4, 6, 7, 7.5, and 8 hrs. There was a treatment effect for cortisol (P \u3c 0.01) and epinephrine (P = 0.003) with ZIL having decreased concentrations. Glucose concentrations within the longissimus muscle were greater (P = 0.03) in CON heifers. Lactate concentrations and glycolytic potential within the biceps femoris were greater in CON heifers (P = 0.05). A treatment effect (P ≤ 0.02) was observed for calcium and potassium, with ZIL heifers having decreased concentrations. Zilpaterol heifers had increased concentrations of creatinine (P = 0.02). A treatment x time interaction (P = 0.02) was observed for phosphorus. Raw liver weights tended (P = 0.08) to be less in ZIL heifers. These data suggest some variations between treatments in terms of response to ZH supplementation and challenge; however, in the environmental conditions of this study, the data suggests that the supplementation of ZH does not negatively alter the status of homeostasis in cattle. Advisor: Ty B. Schmid

Global Gene Expression and DNA Methylation of the Hypothalamus in Feeder Calves Fed a High Concentrate Diet upon Entering Feedlot Phase

Feedlot finishing diets contain high energy to allow for rapid growth and fat deposition. Previous studies have shown the use of high concentrate diets changed DNA methylation and expression of genes in the hypothalamus involved with regulating feed intake, metabolism, signaling, and neuronal communication. This study investigates whether feeding a high concentrate diet to calf-feds enter the feedlot could alter DNA methylation in the hypothalamus affecting expression of growth and development genes. Angus-influenced steers (n=12) were randomly allocated to 2 treatment groups: 1) High Energy/High Concentrate (HE/HC, 1.33Mcal/kg net energy gain NEg) for 202 days; or 2) traditional Backgrounding/Finishing (B/F), fed to provide 1.10Mcal/kg NEg for the first 84 days then 1.43Mcal/kg NE gain for the remaining 118 days. Growth from day 28 to 105 (P0.10) and WBSF (P\u3e0.37) were detected. There were 335 loci differentially expressed (

The Effects of Trace Mineral Supplementation on Performance, Health, and Carcass Quality of At-Risk Mineral Deficient Feedlot Cattle

Morbidity in feedlot cattle due to disease is a common economical loss for feedlot producers. Utah is not typically considered a ‘feedlot state’, but there are several producers in the southern part of the state that specialize in receiving at-risk cattle. These cattle are at-risk because they are coming from areas known to be mineral deficient. Areas such as the western US, are known to be deficient in several trace minerals important in immune response. Therefore, it is critical that producers have an adequate plan to decrease the negative effects that this has on economic viability of their beef operations, especially for those feedlots specializing in receiving at-risk cattle. In this study yearling Black Angus steers received one of four treatments: no mineral supplementation, oral supplementation of minerals provided at levels similar to NRC requirements, oral supplementation of minerals provided at levels above NRC requirements, or a MultiMin® injection at labeled dose. Liver and blood samples were collected to measure mineral status and cortisol levels. Back fat and ribeye area measurements were also recorded. Weight of the steers were recorded every two weeks to determine average daily gain and feed:gain ratio. At the end of the study, steers were harvested at a local harvesting plant and carcass traits were obtained and recorded. There were no differences in weight gain, overall average daily gain, dry matter intake, or feed:gain ratio between the different treatment groups. Steers that were fed the HM had increased liver copper and selenium concentrations, but there was no effect observed on liver manganese and zinc concentrations. Carcass quality and antibody titers did not differ between the different treatments. These data indicate that different mineral supplementation strategies have a diverse effect on feedlot performance and liver mineral concentrations over time, and additional research is needed to better understand these differences

Evaluation of the Interaction of Beta-Adrenergic Agonists Supplementation and Heat Stress on Growth Performance and Carcass Composition in Feeder Lambs

Forty-nine crossbred feeder lambs (wethers, n = 49; 53.3 ± 3.7 kg BW) were utilized to evaluate the interaction of b - adrenergic agonist (bAA) supplementation and heat stress on growth performance and carcass composition. Utilizing and 3 x 2 factorial design, lambs were randomly assigned to one of three bAA supplementation: 1) Control, CON, 2) Ractopamine Hydrochloride at 40 mg/hd/d, RHCL, and Zilpaterol Hydrochloride at 2.5 mg/hd/d, ZHCL for a period of 20 d and one of two environmental conditions (Thermal Neutral: TN and Heat Stress: HS). The TN environment had a constant thermal heat index (THI) of 16.6°C. Within the HS environment, a cyclic design was utilized to achieve a THI of 29.5ºC from 10:00 to 20:00 h and a THI of 24.5ºC from 22:00 to 08:00 h. Starting at 08:01 and continuing to 09:59 h, temperature and RH were gradually increased to achieve a THI of 29.5ºC at 10:00 h and reduction of temperature and RH from 20:01 to 21:59 h to achieve a THI of 24.5ºC at 22:00 h. Regardless of bAA supplementation (P = ≥ 0.09), lambs exposed to the HS environment had reduced DMI (P \u3c 0.001), ADG (P = 0.002), and final BW (P = 0.03). In addition, exposure to the HS environment (regardless of bAA supplementation; P = ≥ 0.07) decreased HCW (P \u3c 0.001), percent change in LM area (P = 0.004) and percent change in LM depth (P = 0.005). There was a bAA x environment interaction associated with RHCL supplementation and heat stress (P = 0.003). Lambs supplemented RHCL in the HS environment had reduced (P = 0.003) respiration rates, when compared to CON and ZHCL supplemented lambs. Supplementation of ZHCL decreased adipose tissue (P = 0.05) and increased percent fat free lean (P = 0.01), when compared to RHCL and CON lambs. Within the current study, both heat stress and bAA supplementation had an impact on growth performance and carcass composition. However, the data does not indicate that there was any significant interaction between bAA supplementation within a heat stress environment on growth performance or carcass composition in feeder lambs. Advisor: Ty B. Schmid