Daily injection of the β2 adrenergic agonist clenbuterol improved poor muscle growth and body composition in lambs following heat stress-induced intrauterine growth restriction

Background: Intrauterine growth restriction (IUGR) is associated with reduced β2 adrenergic sensitivity, which contributes to poor postnatal muscle growth. The objective of this study was to determine if stimulating β2 adrenergic activity postnatal would rescue deficits in muscle growth, body composition, and indicators of metabolic homeostasis in IUGR offspring. Methods: Time-mated ewes were housed at 40°C from day 40 to 95 of gestation to produce IUGR lambs. From birth, IUGR lambs received daily IM injections of 0.8 μg/kg clenbuterol HCl (IUGR+CLEN; n = 11) or saline placebo (IUGR; n = 12). Placebo-injected controls (n = 13) were born to pair-fed thermoneutral ewes. Biometrics were assessed weekly and body composition was estimated by ultrasound and bioelectrical impedance analysis (BIA). Lambs were necropsied at 60 days of age. Results: Bodyweights were lighter (p ≤ 0.05) for IUGR and IUGR+CLEN lambs than for controls at birth, day 30, and day 60. Average daily gain was less (p ≤ 0.05) for IUGR lambs than controls and was intermediate for IUGR+CLEN lambs. At day 58, BIA-estimated whole-body fat-free mass and ultrasound-estimated loin eye area were less (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. At necropsy, loin eye area and flexor digitorum superficialis muscles were smaller (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. Longissimus dorsi protein content was less (p ≤ 0.05) and fat-to-protein ratio was greater (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. Semitendinosus from IUGR lambs had less (p ≤ 0.05) β2 adrenoreceptor content, fewer (p ≤ 0.05) proliferating myoblasts, tended to have fewer (p = 0.08) differentiated myoblasts, and had smaller (p ≤ 0.05) muscle fibers than controls. Proliferating myoblasts and fiber size were recovered (p ≤ 0.05) in IUGR+CLEN lambs compared to IUGR lambs, but β2 adrenoreceptor content and differentiated myoblasts were not recovered. Semitendinosus lipid droplets were smaller (p ≤ 0.05) in size for IUGR lambs than for controls and were further reduced (p ≤ 0.05) in size for IUGR+CLEN lambs. Conclusion: These findings show that clenbuterol improved IUGR deficits in muscle growth and some metabolic parameters even without recovering the deficit in β2 adrenoreceptor content. We conclude that IUGR muscle remained responsive to β2 adrenergic stimulation postnatal, which may be a strategic target for improving muscle growth and body composition in IUGR-born offspring.

Evaluation of Precision Livestock Technology and Human Scoring of Nursery Pigs in a Controlled Immune Challenge Experiment

The objectives were to determine the sensitivity, specificity, and cutoff values of a visual-based precision livestock technology (NUtrack), and determine the sensitivity and specificity of sickness score data collected with the live observation by trained human observers. At weaning, pigs (n = 192; gilts and barrows) were randomly assigned to one of twelve pens (16/pen) and treatments were randomly assigned to pens. Sham-pen pigs all received subcutaneous saline (3 mL). For LPS-pen pigs, all pigs received subcutaneous lipopolysaccharide (LPS; 300 μg/kg BW; E. coli O111:B4; in 3 mL of saline). For the last treatment, eight pigs were randomly assigned to receive LPS, and the other eight were sham (same methods as above; half-and-half pens). Human data from the day of the challenge presented high true positive and low false positive rates (88.5% sensitivity; 85.4% specificity; 0.871 Area Under Curve, AUC), however, these values declined when half-and-half pigs were scored (75% sensitivity; 65.5% specificity; 0.703 AUC). Precision technology measures had excellent AUC, sensitivity, and specificity for the first 72 h after treatment and AUC values were >0.970, regardless of pen treatment. These results indicate that precision technology has a greater potential for identifying pigs during a natural infectious disease event than trained professionals using timepoint sampling.

12 Growth Performance, Physiology, and Carcass Merit of Supplementing Brahman Steers with Zilpaterol Hydrochloride Under Heat Stress Conditions

Supplementation with a β- adrenergic agonist (β-AA) for 21 days in Brahman steers under heat stress conditions (HS) was evaluated with respect to feedlot performance and carcass merit. Twenty-four Brahman steers (kg = 338 ± 39) were housed in two controlled environment chambers with one of two environmental (ENV) conditions 1) heat stress (HS; THI = 73 to 85) and 2) thermoneutral (TN; THI = 68) with either Zilpaterol hydrochloride (ZL) or soymeal supplementation (CN) using a randomly assigned in a 2 x 2 factorial design (n=6/group). Daily data were collected for dry matter intake, water intake, respiratory rate (RR), and rectal temperature (RT). At the end of 21 d period, total weight gain was used to calculate average daily gain (ADG) and gain to feed. Blood samples were collected from the jugular vein on days -7, 3, 10, and 21 for cortisol analysis, and biological impedance analysis (BIA) was determined on days 3, 10, and 21 on each animal. Steers were harvested at 544 kg on average post supplementation/environment conditions, and carcass merit was determined. There were no differences (P > 0.05) in feedlot performance. Brahmans exposed to heat stress had greater RR during the heat stress periods of the experiment, regardless of supplementation. Environment and day interactions (P < 0.04) were observed for RT, HS steers had a greater RT on d 8 but similar RT on d 15 and 19. Stressed steers with ZL had higher RT (P < 0.05) than TN/CN steers on d 11. There was no interaction (P > 0.05) between environmental conditions and CN and ZH supplementation for cortisol concentrations. Regardless of environmental treatment or supplementation, no difference (P > 0.05) was associated with BIA characteristics. There were no differences (P > 0.05) for hot carcass weight, cold carcass weight, USDA yield grade, 12th rib loin eye area, marbling score, KPH percentage, and 12th rib fat thickness between groups. Twelfth-rib loin eye area lean color from HS/CN had higher lightness (L*) (P < 0.05) than TN/CN steers. HS/CN steers present a similar (L*) to ZL in TN and HS conditions. Redness-greenness (a*) was greater (P = 0.01) in carcasses from HS steers with or without ZL than TN/ZL but similar to TN/CN. Steers exposed to HS and CN had a higher (P = 0.02) change of 12th rib lean color from yellow to blue (b*) than TN steers with CN and ZL. Supplementation with β-AA did not negatively impact growth, carcass performance, or carcass merit in heat-stressed steers.

PSIII-A-2 Administering Anti-Inflammatory Dexamethasone or Fish oil Mitigated Components of the Inflammatory Response to Chronic Heat Stress and Improved Average Daily Gain in Whether Lambs

Heat-stressed livestock exhibit systemic inflammation, which likely contributes to poor growth and metabolism even when nutritional effects are controlled by pair feeding. Thus, heat stress-induced deficits in growth, metabolism, and well-being may be improved by moderating heightened inflammation. Our objective was to determine whether targeting inflammation by administering anti-inflammatory dexamethasone or fish oil would mitigate blood indicators of inflammation and improve average daily gain (ADG) in heat-stressed lambs. Wether lambs were randomly assigned to 30d of heat stress (40°C, THI=88) or thermoneutral (pair-fed controls; 25°C, THI=70; n=11) conditions. Heat-stressed lambs were randomly assigned to receive no intervention (HS; n=11), oral boluses of fish oil (HS+FO; 360mg; n=11) twice daily, or IM injection of dexamethasone (HS+DEX; 0.15mg/kg; n=11) every 72h. Throughout the study, rectal temperatures and respiration rates were greater (P< 0.05) for HS, HS+DEX, and HS+FO than for controls. Plasma TNFα was greater (P< 0.05) for HS lambs (528±31pg/ml) than for controls (341±28pg/ml), HS+DEX (423±39pg/ml), or HS+FO lambs (376±38pg/ml). Total white blood cells and monocytes were greater (P< 0.05) for HS, HS+DEX, and HS+FO lambs than for controls. Granulocytes and granulocyte:lymphocyte were greater (P< 0.05) for HS and HS+DEX but not HS+FO than for controls. Lymphocytes did not differ among groups and platelets were less (P< 0.05) for HS+FO than for other groups. Blood pH was greater (P< 0.05) for HS, HS+DEX, and HS+FO than for controls early in the study but did not differ by d 30. Blood HCO3 was less (P< 0.05) for HS but not HS+DEX or HS+FO lambs than for controls throughout the study. ADG was reduced (P< 0.05) by 22% for HS lambs but not for HS+DEX or HS+FO lambs compared to controls. These data indicate that supplementing anti-inflammatory agents to chronically heat-stressed lambs improved growth by reducing components of the inflammatory response.

40 The Impact of Sire EBV for Growth and Feed Intake on Pig Activity Level Using Nuutrack

Feed cost accounts for two-thirds of the total cost in producing pork. The principle in reducing feed costs, without sacrificing pork output, is improving feed efficiency. To date, the two traits commonly associated with improving feed efficiency are growth and feed intake; however the impact they have on maintenance levels is unclear. Therefore, the objective of this study was to determine activity and behavior patterns of progeny using NUtrack from sires with different EBV combinations for growth and feed intake. A total of 175 pigs from four different sire groups (DNA Genetics Line 600; High Growth/High Feed Intake, HGHI; High Growth/Low Feed Intake, HGLI; Low Growth/High Feed Intake, LGHI; and Low Growth/Low Feed Intake, LGLI) were utilized at the UNL ENREC swine farm. Finisher pens were blocked by sire group and sex. Finisher exit weights were collected after 85 days, along with loin-eye area (LEA) and backfat (BF). NUtrack algorithms allowed for individual identification of pigs in a group housing setting to track daily activity behaviors including distance traveled (DIST) and time lying (LIE). Estimated marginal means were processed through RStudio. HIHG pigs traveled less DIST than those sired by LILG, HILG, and LIHG (P < 0.05; 929 vs. 1,066, 990, and 984m, respectively). The HIHG pigs had greater LIE time than LIHG and LILG pigs (P < 0.05; 1,119 vs. 1,188 and 1,175min, respectively). LILG pigs had greater LEA compared with HIHG, HILG, and LIHG sired pigs (P < 0.05; 52.85 vs. 49.39, 49.97, and 51.05cm2, respectively). The LILG pigs had less BF compared with HIHG, HILG, and LIHG sired pigs (P < 0.05; 1.42 vs. 1.48, 1.46, and 1.50cm, respectively). These results suggest that pigs from boars with high EBVs for growth travel less, spend more time lying and yield a fatter carcass.

PSIII-A-8 Daily Clenbuterol Administration to Lambs Born with low Birthweight due to Intrauterine Growth Restriction Recovered Growth Rates and Improved Body Composition at 60 D of age

Low birthweight due to intrauterine growth restriction (IUGR) results from unfavorable in utero conditions (i.e., hypoxemia, hypoglycemia) that impairs growth capacity for muscle and other tissues. This programming effect reduces growth efficiency in IUGR offspring below their genetic potential. Specific programming mechanisms are not known, but recent evidence indicates reduced β2 adrenergic regulation of IUGR muscle. Thus, our objective was to determine if early-life growth deficits in IUGR juvenile lambs are improved by manipulating β2 adrenergic activity with daily IM administration of the β2 agonist, clenbuterol (Clen), from birth to 60 d of age. Maternal heat stress-induced IUGR (n=10) and IUGR+Clen (n=9) lambs were smaller (P< 0.05) than controls (n=11) at birth, weighed 18% and 11% less (P< 0.05), respectively, than controls at 30 d of age, and weighed 16% and 13% less (P< 0.05), respectively, at 60 d of age. Average daily gain at 30 and 60 d of age was reduced (P≤0.05) for IUGR but not IUGR+Clen lambs compared to controls. Bioelectrical impedance analysis was used to estimate body composition in live lambs at 58 d of age. Estimated fat-free lean mass and estimated muscle mass were less (P≤0.05) for IUGR but not IUGR+Clen lambs compared to controls. Estimated protein and fat content as well as protein:fat were likewise reduced (P< 0.05) for IUGR but not IUGR+Clen lambs. At necropsy, whole hindlimbs tended to be lighter (P≤0.09) and flexor digitorum superficialis muscle was lighter (P< 0.05) for IUGR but not IUGR+Clen lambs compared to controls. Loin-eye areas measured in chilled carcasses were 15% smaller (P< 0.05) for IUGR lambs and 19% larger (P< 0.05) for IUGR+Clen lambs compared to controls. From this study, we conclude that poor postnatal growth and body composition observed in IUGR juvenile lambs was improved when clenbuterol was used to target programmed deficits in β2 adrenergic regulation of muscle.

Primary myoblasts from intrauterine growth-restricted fetal sheep exhibit intrinsic dysfunction of proliferation and differentiation that coincides with enrichment of inflammatory cytokine signaling pathways

Intrauterine growth restriction (IUGR) is linked to lifelong reductions in muscle mass due to intrinsic functional deficits in myoblasts, but the mechanisms underlying these deficits are not known. Our objective was to determine if the deficits were associated with changes in inflammatory and adrenergic regulation of IUGR myoblasts, as was previously observed in IUGR muscle. Primary myoblasts were isolated from IUGR fetal sheep produced by hyperthermia-induced placental insufficiency (PI-IUGR; n = 9) and their controls (n = 9) and from IUGR fetal sheep produced by maternofetal inflammation (MI-IUGR; n = 6) and their controls (n = 7). Proliferation rates were less (P < 0.05) for PI-IUGR myoblasts than their controls and were not affected by incubation with IL-6, TNF-α, norepinephrine, or insulin. IκB kinase inhibition reduced (P < 0.05) proliferation of control myoblasts modestly in basal media but substantially in TNF-α-added media and reduced (P < 0.05) PI-IUGR myoblast proliferation substantially in basal and TNF-α-added media. Proliferation was greater (P < 0.05) for MI-IUGR myoblasts than their controls and was not affected by incubation with TNF-α. Insulin increased (P < 0.05) proliferation in both MI-IUGR and control myoblasts. After 72-h differentiation, fewer (P < 0.05) PI-IUGR myoblasts were myogenin+ than controls in basal and IL-6 added media but not TNF-α-added media. Fewer (P < 0.05) PI-IUGR myoblasts were desmin+ than controls in basal media only. Incubation with norepinephrine did not affect myogenin+ or desmin+ percentages, but insulin increased (P < 0.05) both markers in control and PI-IUGR myoblasts. After 96-h differentiation, fewer (P < 0.05) MI-IUGR myoblasts were myogenin+ and desmin+ than controls regardless of media, although TNF-α reduced (P < 0.05) desmin+ myoblasts for both groups. Differentiated PI-IUGR myoblasts had greater (P < 0.05) TNFR1, ULK2, and TNF-α-stimulated TLR4 gene expression, and PI-IUGR semitendinosus muscle had greater (P < 0.05) TNFR1 and IL6 gene expression, greater (P < 0.05) c-Fos protein, and less (P < 0.05) IκBα protein. Differentiated MI-IUGR myoblasts had greater (P < 0.05) TNFR1 and IL6R gene expression, tended to have greater (P = 0.07) ULK2 gene expression, and had greater (P < 0.05) β-catenin protein and TNF-α-stimulated phosphorylation of NFκB. We conclude that these enriched components of TNF-α/TNFR1/NFκB and other inflammatory pathways in IUGR myoblasts contribute to their dysfunction and help explain impaired muscle growth in the IUGR fetus.

Short Communication: Beta-adrenergic agonists alter oxidative phosphorylation in primary myoblasts

Beta-adrenergic agonists (β-AAs) are widely used supplements in beef and pork production to improve feed efficiency and increase lean muscle mass, yet little is known about the molecular mechanism by which β-AAs achieve this outcome. Our objective was to identify the influence of ractopamine HCl and zilpaterol HCl on mitochondrial respiratory activity in muscle satellite cells isolated from crossbred beef steers (N = 5), crossbred barrows (N = 2), Yorkshire-cross gilts (N = 3), and commercial weather lambs (N = 5). Real-time measurements of oxygen consumption rates (OCRs) were recorded using extracellular flux analyses with a Seahorse XFe24 analyzer. After basal OCR measurements were recorded, zilpaterol HCl, ractopamine HCl, or no β-AA was injected into the assay plate in three technical replicates for each cell isolate. Then, oligomycin, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone, and rotenone were injected into the assay plate sequentially, each inducing a different cellular state. This allowed for the measurement of OCR at these states and for the calculation of the following measures of mitochondrial function: basal respiration, non-mitochondrial respiration, maximal respiration, proton leak, adenosine triphosphate (ATP)-linked respiration, and spare respiratory capacity. Incubation of bovine cells with either zilpaterol HCl or ractopamine HCl increased maximal respiration (P = 0.046) and spare respiratory capacity (P = 0.035) compared with non-supplemented counterparts. No difference (P > 0.05) was observed between zilpaterol HCl and ractopamine HCl for maximal respiration and spare respiratory capacity in bovine cell isolates. No measures of mitochondrial function (basal respiration, non-mitochondrial respiration, maximal respiration, proton leak, ATP-linked respiration, and spare respiratory capacity) were altered by β-AA treatment in ovine or porcine cells. These findings indicate that β-AAs in cattle may improve the efficiency of oxidative metabolism in muscle satellite cells by modifying mitochondrial respiratory activity. The lack of response by ovine and porcine cells to β-AA incubation also demonstrates differing physiological responses to β-AA across species, which helps to explain the variation in its effectiveness as a growth supplement.

Evaluation of a novel computer vision-based livestock monitoring system to identify and track specific behaviors of individual nursery pigs within a group-housed environment

Animal behavior is indicative of health status and changes in behavior can indicate health issues (i.e., illness, stress, or injury). Currently, human observation (HO) is the only method for detecting behavior changes that may indicate problems in group-housed pigs. While HO is effective, limitations exist. Limitations include HO being time consuming, HO obfuscates natural behaviors, and it is not possible to maintain continuous HO. To address these limitations, a computer vision platform (NUtrack) was developed to identify (ID) and continuously monitor specific behaviors of group-housed pigs on an individual basis. The objectives of this study were to evaluate the capabilities of the NUtrack system and evaluate changes in behavior patterns over time of group-housed nursery pigs. The NUtrack system was installed above four nursery pens to monitor the behavior of 28 newly weaned pigs during a 42-d nursery period. Pigs were stratified by sex, litter, and randomly assigned to one of two pens (14 pigs/pen) for the first 22 d. On day 23, pigs were split into four pens (7 pigs/pen). To evaluate the NUtrack system’s capabilities, 800 video frames containing 11,200 individual observations were randomly selected across the nursery period. Each frame was visually evaluated to verify the NUtrack system’s accuracy for ID and classification of behavior. The NUtrack system achieved an overall accuracy for ID of 95.6%. This accuracy for ID was 93.5% during the first 22 d and increased (P &lt; 0.001) to 98.2% for the final 20 d. Of the ID errors, 72.2% were due to mislabeled ID and 27.8% were due to loss of ID. The NUtrack system classified lying, standing, walking, at the feeder (ATF), and at the waterer (ATW) behaviors accurately at a rate of 98.7%, 89.7%, 88.5%, 95.6%, and 79.9%, respectively. Behavior data indicated that the time budget for lying, standing, and walking in nursery pigs was 77.7% ± 1.6%, 8.5% ± 1.1%, and 2.9% ± 0.4%, respectively. In addition, behavior data indicated that nursery pigs spent 9.9% ± 1.7% and 1.0% ± 0.3% time ATF and ATW, respectively. Results suggest that the NUtrack system can detect, identify, maintain ID, and classify specific behavior of group-housed nursery pigs for the duration of the 42-d nursery period. Overall, results suggest that, with continued research, the NUtrack system may provide a viable real-time precision livestock tool with the ability to assist producers in monitoring behaviors and potential changes in the behavior of group-housed pigs.

Transcriptome analyses indicate that heat stress-induced inflammation in white adipose tissue and oxidative stress in skeletal muscle is partially moderated by zilpaterol supplementation in beef cattle

Heat stress (HS) triggers oxidative stress, systemic inflammation, and disrupts growth efficiency of livestock. β-adrenergic agonists supplemented to ruminant livestock improve growth performance, increase skeletal muscle mass, and decrease carcass fat. The objective of this study was to understand the independent and interacting effects of HS and zilpaterol hydrochloride (ZH) supplementation on the transcriptome of subcutaneous white adipose tissue and the longissimus dorsi muscle in steers. Twenty-four Red Angus-based steers were assigned to thermoneutral (TN; Temperature Humidity Index [THI] = 68) or HS (THI = 73-85) conditions and were not supplemented or supplemented with ZH (8.33 mg/kg/d) for 21 d in a 2 × 2 factorial. Steers in the TN condition were pair-fed to the average daily feed intake of HS steers. RNA was isolated from adipose tissue and skeletal muscle samples collected via biopsy on 3, 10, and 21 d and sequenced using 3' Tag-Seq to an achieved average depth of 3.6 million reads/sample. Transcripts, mapped to ARS-UCD1.2, were quantified. Differential expression (DE) analyses were performed in DESeq2 with a significance threshold for false discovery rate of 0.05. In adipose, 4 loci (MISP3, APOL6, SLC25A4, and S100A12) were DE due to ZH on day 3, and 2 (RRAD, ALB) were DE due to the interaction of HS and ZH on day 10 (Padj < 0.05). In muscle, 40 loci (including TENM4 and OAZ1) were DE due to ZH on day 10, and 6 loci (HIF1A, LOC101903734, PDZD9, HNRNPU, MTUS1, and TMCO6) were DE due to environment on day 21 (Padj < 0.05). To explore biological pathways altered by environment, supplement, and their interaction, loci with DE (Praw < 0.05) were evaluated in Ingenuity Pathway Analysis. In adipose, 509 pathways were predicted to be altered (P < 0.01): 202 due to HS, 126 due to ZH, and 181 due to the interaction; these included inflammatory pathways predicted to be upregulated due to HS but downregulated due to the interaction of HS and ZH. In muscle, 113 pathways were predicted to be altered (P < 0.01): 23 due to HS, 66 due to ZH, and 24 due to the interaction of HS and ZH. Loci and pathway data in muscle suggest HS induced oxidative stress and that the stress response was moderated by ZH. Metabolic pathways were predicted to be altered due to HS, ZH, and their interaction in both tissues. These data provide evidence that HS and ZH interact to alter expression of genes in metabolic and immune function pathways and that ZH moderates some adverse effects of HS.

Sustained heat stress elevated corneal and body surface temperatures and altered circulating leukocytes and metabolic indicators in wether lambs supplemented with ractopamine or zilpaterol

Understanding how β adrenergic agonists influence the physiology of heat stress could lead to mitigation options. We sought to investigate body surface temperatures in feedlot wethers supplemented with ractopamine or zilpaterol and exposed to heat stress for 18 d. Corneal and skin temperatures were assessed via infrared thermography at 1- and 2-m distances. Rectal temperatures and circulating leukocytes, metabolites, and electrolytes were also measured. Heat stress increased (P < 0.05) rectal temperatures in unsupplemented and zilpaterol-supplemented lambs but not in ractopamine-supplemented lambs. Heat stress also increased (P < 0.05) surface temperatures of the cornea, nose, ear, and back, regardless of supplement. Observations were comparable between thermography performed at 1 and 2 m, and higher emissivity settings generally produced less variation. Heat stress tended to increase (P = 0.08) blood monocytes in unsupplemented but not ractopamine- or zilpaterol-supplemented lambs. Granulocytes were increased (P < 0.05) by heat stress in ractopamine-supplemented lambs but decreased (P < 0.05) in zilpaterol-supplemented lambs. Blood glucose, triglycerides, and cholesterol did not differ among groups, and blood lactate was reduced (P < 0.05) by heat stress in zilpaterol-supplemented lambs only. Blood Na+ was reduced (P < 0.05) and Ca2+ increased (P < 0.05) by heat stress, regardless of supplement. These findings indicate that β1- and β2-adrenergic agonists differentially relieve some but not all heat stress-induced changes in stress indicators. Moreover, corneal and skin surface temperatures measured by infrared thermography reasonably identified body temperature changes at a distance of 2 m.

130 Utilization of Nutrack to Assess Variance Components and Heritability of Activity Traits

Overall activity and behavior are integral components of sows remaining productive in the herd. This investigation studied overall activity of group housed replacement gilts and the heritability of various activity traits. Beginning around 20 wk of age, video recorded data of approximately 75 gilts/group for a total of 2,378 gilts over 32 groups was collected for 7 consecutive d using the NUtrack System, which tracks distance travelled (m), avg speed (m/s), angle rotated (degrees), and time standing (s), sitting (s), eating (s), and laying (s). The recorded phenotypes were standardized to the distribution observed within a pen for each group. The final values used for analysis were the average daily standardized values. Data were analyzed using mixed models (RStudio V 1.2.5033) including effects of sire, dam, dam’s sire and dam, dam’s grandsire and granddam, farrowing group, barn, pen, and on-test date. Sire had an effect on every activity trait P &lt; 0.001), and dam had an effect on average speed (P &lt; 0.001). The dam’s sire had an effect on all activity traits (P &lt; 0.001) and the dam’s grandsire had an effect on average speed (P &lt; 0.001). Heritabilities and variance components of activity traits were estimated in ASReml 4 using an animal model with a two-generation pedigree. Genetic variances are 0.17 +/- 0.029, 0.19 +/- 0.034, and 0.11 +/- 0.024, residual variances are 0.37 +/- 0.023, 0.41 +/- 0.027, and 0.41 +/- 0.022, phenotypic variances are 0.54 +/- 0.018, 0.60 +/- 0.020, and 0.52 +/- 0.016, and heritabilities are 0.32 +/- 0.048, 0.32 +/- 0.049, and 0.21 +/- 0.044 for average speed, distance, and lie respectively. NUtrack offers potential to aid in selection decisions. Given the results presented herein, continued investigation into these activity traits and their association with sow longevity is warranted.

42 Activity and Bone Lesion Analysis on Gilt Retention to the Breeding Herd

A consistent theme in swine production is to increase efficiency and reduce input costs. In this study, sow activity traits and lesions were analyzed to identify associations with lameness and gilt retention. Gilts (n = 73) were culled based on structural unsoundness as determined by an experienced herdsman. Females (n = 132) that had been retained for breeding, but either did not show estrus at an appropriate age or were excessed due to limited farrowing space were used as controls. Gilts were recorded with the NUtrack System for 1 week prior to selection. The NUtrack System records distance travelled (m), time standing (s), eating (s), and laying (s), angle rotated (degrees) and average speed (m/s). Animals were humanely harvested in a USDA inspected abattoir. Both ends of the humerus and the femur head were evaluated for osteochondrosis or osteoarthritis lesions. Joint lesions were categorized as Major or Minor lesions. Major lesions were severe osteochondrosis lesions where cartilage was severely fractured or cartilage exhibited a region of necrosis larger than 2 millimeters in diameter. Minor lesions were defined creases or indentations in the cartilage or where abnormal blood flow existed in bone tissue underneath cartilage. Ninety-eight animals were identified with minor or major lesions (28 cull and 70 control). Unexpectedly, chi-square analysis did identify control animals as having higher incidences of minor or major lesions than cull animals (p &lt; 0.05). Data were analyzed using logistic regression (RStudio V1.2.5033) with farrowing group included in the model. No NUtrack trait was predictive of joint lesions (P &gt; 0.1). However, time standing (P &lt; 0.001) and average speed (P &lt; 0.05) were significantly associated with being retained for breeding. These data suggest that animal behavior and movement, as analyzed by NUtrack, can enhance herdsman efforts in making culling decisions of breeding animals.

181 Utilization of the Nutrack Livestock Monitoring System to Identify Changes in General and Spatial Behaviors of Newly Weaned Nursery Exposed to an Endotoxin Challenge

Incorporation of precision livestock technology has the potential to provide swine producers with the means to rapidly and accurately identify immune-compromised pigs, allowing for accurate and timely interventions. The objective of this study was to utilize the NUtrack System (NUtrack) to identify changes in general (lying, standing and sitting) and spatial behaviors (at the feeder and meters/day) of newly weaned pigs exposed to a lipopolysaccharide (LPS) challenge. To achieve this objective, 12 nursery pens with 192 weaned pigs (16 pigs/pen) were randomly assigned to three treatments (4 pens/treatment): Control (saline injection), Mixed (8 pigs/pen received an LPS challenge and 8 pigs received saline injection) and 100% (all pigs received LPS). The LPS challenge consisted of a bolus subcutaneous injection at 300 µg/kg BW (E. coli O111:B4). Prior to placement, NUtrack was installed above the 12 nursery pens and initiated continuous data capture for the duration of the nursery phase (43 days). Ten days after placement in the nursery pens pigs received the assigned challenge (LPS or sham). Data were analyzed using the MIXED procedure of SAS specific for repeated measures (SAS Inst. Inc., Cary, NC). Regardless of treatment group, general special behaviors were similar (P = &gt;0.28) prior to the LPS challenge (days 1–9). Following LPS challenge (day 10), spatial behaviors decreased (P = &lt;0.01) and time associated with general behaviors increased (P = &lt;0.01) for LPS challenged pigs when compared to pigs not challenged (Control and 50% non-challenged). This change in both general and spatial behaviors remained until day 12. In addition, general and spatial behaviors of the 50% treatment (challenged and non-challenged) were different (P = &lt; 0.03), when compared to Controls. Results suggest precision livestock technology, like the NUtrack System, has the potential to monitor changes in behaviors following an endotoxin challenge.

131 Zilpaterol Hydrochloride and Heat Stress Each Alter the Cattle Adipose Transcriptome and Predicted to Alter Molecular Pathways After 21 Days

Heat stress reduces livestock performance while supplementation of beta-adrenergic agonists (βAA) such as zilpaterol hydrochloride (ZH) improve production efficiency; both stimulate lipolysis. The objective of this study was to understand the effects (independent, interacting) of heat stress and ZH on the subcutaneous adipose transcriptome in fed steers. 24 Red Angus steers were assigned to thermoneutral (TN; THI=68) or heat stress (HS; THI=83) conditions and fed no supplement (NS) or ZH (8.33 mg/kg/day) for 21d in a 2x2 factorial. TN steers were pair-fed the HS daily average. Subcutaneous adipose samples were collected at day -3, 3, 10, and 21. RNA was isolated and sequenced using 3’ Tag-Seq reads to a depth of 3.6 million reads/sample. Transcripts were mapped to ARS-UCD1.2 and quantified. After quality control, differential expression (DE) analyses were performed in DESeq2 with a significance threshold (FRD) of 0.05. Pathway analysis was used to explore pathways affected by HS, ZH, and their interaction using DE loci (P &lt; 0.05). The acute phase response signaling pathway was predicted to be activated at 3d, but inhibited at 10d and 21d by the combination of HS and ZH. At multiple time points, inflammatory pathways including those for interferon and IL-8 were predicted to be activated by HS. Mitochondrial function pathways including oxidative phosphorylation, mitochondrial dysfunction, and TCA cycle II were altered by ZH. Adipose centric pathways for phospholipase-C and protein kinase-A signaling were altered by HS/ZH interaction while glycolysis was altered solely by HS. These data support the hypothesis that exposing cattle to HS conditions and ZH supplementation alters the subcutaneous adipose transcriptome, but not necessarily in an additive fashion. These data provide information regarding the supplementation of βAA in heat stress environments, especially if it mediates the effects of HS.

PSI-14 Feeding β-agonists under heat stress conditions in feedlot cattle

Red Angus steers (n = 24; 260 ± 25 kg) were used to analyze the effects of supplementation of zilpaterol hydrochloride (ZH) under heat stress conditions on respiration rate (RR), rectal temperature (RT), growth performance (GP), and carcass traits (CT). Steers were randomly assigned to a 2 x 2 factorial treatment arrangement (n = 6/group) with factors including heat stress (HS; THI=71 to 83) or thermal neutral (TN; THI=27 to 39) conditions and with/without supplementation of ZH (0 or 8.38 mg/kg/d on 88% DM basis). Steers were provided 9 d to acclimate to tie stalls rooms under TN conditions before starting the study. TN steers were pair-fed to the average daily dry matter intake (DMI) of HS steers. Ad libitum water consumption (WC) was recorded daily. HS and TN steers were harvested on d 22 and 23, respectively. By design, DMI was not different between environments (P = 0.43). DMI also did not differ between supplement groups (P = 0.31). RT, RR, and WC were greater (P &lt; 0.01) in HS steers compared to TN steers. There was a supplement by environment interaction (P = 0.02) for RT, as HS steers fed ZH had lower RT than HS control steers (39.1 vs 39.5 ℃). ADG was 20% higher (P = 0.04) in HS steers compared to TN steers. CT did not differ (P = &gt;0.05) due to environment, treatment, or interactions between environment and ZH supplementation. Our results suggest that feedlot steers under our experimental conditions display some sensitivity to HS through GP, RR, and RT, however, this did not translate to an impact on CT. Furthermore, ZH supplementation under HS conditions appears to impact thermoregulatory responses positively, yet this did not impact GP or CT.

271 Beta-adrenergic agonists increase maximal output of oxidative phosphorylation in bovine satellite cells

Beta-adrenergic agonists (βAA) are widely used supplements in beef production to improve feed efficiency and increase lean muscle mass, yet little is known about the molecular mechanism by which βAA achieve this outcome. Our objective was to identify the influence of Ractopamine HCl (RH) and Zilpaterol HCl (ZH) on mitochondrial function in muscle stem cells. Satellite cells were isolated from skeletal muscle of cattle (n = 4) and yak (n = 1) at harvest. Cells were exposed to ZH, RH, or no βAA in replicates of four. Real-time measurements of oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) were recorded using intracellular flux analysis. Incubation of bovine (n = 4) cells with either ZH or RH increased maximal respiration (P = 0.004) and spare respiratory capacity (P = 0.013). When yak cells were included, the response to treatment was similar (P = 0.006 and P = 0.006), but an animal effect was also observed (P &lt; 0.02), presumably due to differences in genetic background. These findings indicate that βAA-treated cells have the capacity to respond more efficiently to increased energy demands than non-supplemented cells. Beta-adrenergic agonists improve the efficiency of muscle stem cells in part by modifying mitochondrial function.

256 Heat stress and β-adrenergic agonists alter the adipose transcriptome and fatty acid mobilization in ruminant livestock

Heat stress (HS) negatively impacts livestock performance and carcass traits while beta-adrenergic agonist (βAA) supplementation improves animal production and efficiency; both can stimulate lipolysis in adipose. The objective of this study was to understand the independent and interacting effects of HS and βAA on the subcutaneous adipose transcriptome in lambs and on visceral adipose fatty acid mobilization in steers. For study 1, 24 wethers were assigned to thermal neutral (TN THI = 65) or HS (THI = 80) conditions and supplemented without (NS) or with ractopamine hydrochloride (RH) for 30d in a 2 x 2 factorial. TN lambs were pair-fed the average intake of HS. RNA collected from subcutaneous fat at harvest was sequenced. Differential expression (DE) analyses identified 71 (Padj &lt; 0.05) loci altered due to the interaction of environment and supplement. No DE genes were observed for the main effect of supplement, but HS reduced expression (P &lt; 0.05) of RBM3 and increased expression (P &lt; 0.05) of ATXN7L1. HS was predicted by pathway analyses to impair adipogenesis and fatty acid mobilization. In study 2, 24 steers were assigned to TN (THI = 65) or HS (THI = 83) and NS or zilpaterol hydrochloride (ZH) treatments for 21d in a 2 x 2 factorial. TN steers were pair-fed the intake of their HS cohort. Ex vivo fatty acid mobilization from visceral adipose in response to 0 or 1µM epinephrine was quantified at harvest. Fatty acid mobilization did not differ among groups when unstimulated, but epinephrine-stimulated mobilization was less (P = 0.05) in HS and greater (P &lt; 0.01) in ZH steers. These findings indicate that heat stress-induced reduction of fatty acid mobilization from adipose may be associated with increased expression of stress-responsive genes. Moreover, the stimulatory effect of ZH on epinephrine-induced fatty acid mobilization was present after chronic treatment. Our data have yet to identify an interaction between HS and βAA supplementation that demonstrably impacts well-being.

258 Deficits in growth, muscle mass, and body composition following intrauterine growth restriction persisted in lambs at 60 d of age but were improved by daily clenbuterol supplementation

Intrauterine growth restriction (IUGR) reduces neonatal muscle growth and alters body composition in livestock. Our objective was to determine the effect of IUGR on juvenile growth and assess the benefits of treatment with clenbuterol (β2 adrenergic agonist) in IUGR offspring. Heat stress-induced IUGR lambs were born 28% lighter (P &lt; 0.05) than controls. At 60 d of age, unsupplemented IUGR lambs had reduced (P &lt; 0.05) bodyweight (BW), average daily gain, and crown-rump length compared to controls, but clenbuterol-supplemented IUGR lambs did not differ from controls. Crown circumference, body girth, and cannon bone length did not differ among groups. Bioelectrical impedance in live lambs and carcasses estimated that lean mass and mass of multiple muscle groups were reduced (P &lt; 0.05) in unsupplemented IUGR lambs but not clenbuterol-supplemented IUGR lambs compared to controls. Estimated protein, fat, and protein/fat were likewise reduced (P &lt; 0.05) in unsupplemented but not clenbuterol-supplemented IUGR lambs. Loin-eye area in chilled carcasses was 30% smaller (P &lt; 0.05) in unsupplemented IUGR lambs but 19% larger (P &lt; 0.05) in clenbuterol-supplemented IUGR lambs compared to controls. Proximate analysis revealed greater (P &lt; 0.05) fat and reduced (P &lt; 0.05) protein and protein/fat in loin muscles from unsupplemented but not clenbuterol-supplemented IUGR lambs compared to controls. At necropsy, hindlimbs, hearts, and flexor digitorum superficialis muscles tended to be lighter (P ≤ 0.09) and lungs and kidneys were lighter (P &lt; 0.05) in IUGR lambs. Kidney weight was further reduced (P &lt; 0.05) in clenbuterol-supplemented IUGR lambs. Brain/BW tended to be reduced (P ≤ 0.09) and lung/BW and kidney/BW were reduced (P &lt; 0.05) in IUGR lambs, but lung weight and lung/BW were greater (P &lt; 0.05) in clenbuterol-supplemented compared to unsupplemented IUGR lambs. We conclude that poor growth and asymmetric body composition previously observed in IUGR neonates persists in juveniles, but daily treatment with clenbuterol recovered growth and improved body composition in IUGR lambs.

257 Beef cows with atypical estrous cyclicity at puberty produced calves with deficits in pre-weaning muscling, metabolic indicators, and myoblast function but not in feedlot performance

Economic beef production requires efficient growth. In our herd, cows were identified that exhibited irregular (start-stop) or absent (non-cyclic) pubertal estrous cyclicity prior to their 1st breeding season. These cows were sub-fertile but weaned heavier calves. Here, we determined if these calves possessed enhanced muscling and metabolic efficiency. Early muscle growth and metabolic indicators, feedlot performance, and carcass traits were evaluated in steer calves from cows that had exhibited normal (typical), start-stop, or non-cyclic pubertal estrous patterns. Start-stop and non-cyclic cows calved later (P &lt; 0.05) than typical cows, but calf birthweights did not differ among groups. Weaning weights tended to be decreased (P = 0.09) in calves from start-stop and non-cyclic cows, but 205-d adjusted weaning weights did not differ. At 3 mo, body composition estimated by bioelectrical impedance revealed a tendency for reduced (P = 0.10) muscle mass in calves from non-cyclic and start-stop compared to typical cows. Plasma cholesterol, high-density lipoprotein, and triglyceride concentrations were reduced (P &lt; 0.05) and glucose/insulin tended to be increased (P = 0.09) in calves from non-cyclic cows. Plasma urea nitrogen did not differ among groups. Ex vivo proliferation was greater (P &lt; 0.05) for myoblasts isolated from calves of start-stop and non-cyclic compared to typical cows. Total oxidative metabolism did not differ but glycolysis was decreased (P &lt; 0.05) in myoblasts from calves of non-cyclic cows. Feedlot average daily gain and dry matter intake did not differ during growing or finishing. Feed efficiency tended to be increased (P = 0.09) in calves from non-cyclic cows but not when normalized to dressing percentage. Hot carcass weight, dressing percentage, ribeye area, fat thickness, and marbling did not differ among groups. These findings indicate that atypical maternal estrous cyclicity at puberty reduced early muscle growth and metabolism in offspring but not feedlot growth or carcass merit. We speculate that early growth deficits are influenced by inflammatory changes.

Heat stress-induced deficits in growth, metabolic efficiency, and cardiovascular function coincided with chronic systemic inflammation and hypercatecholaminemia in ractopamine-supplemented feedlot lambs

Heat stress hinders growth and well-being in livestock, an effect that is perhaps exacerbated by the β1 agonist ractopamine. Heat stress deficits are mediated in part by reduced feed intake, but other mechanisms involved are less understood. Our objective was to determine the direct impact of heat stress on growth and well-being in ractopamine-supplemented feedlot lambs. Commercial wethers were fed under heat stress (40 °C) for 30 d, and controls (18 °C) were pair-fed. In a 2 × 2 factorial, lambs were also given a daily gavage of 0 or 60 mg ractopamine. Growth, metabolic, cardiovascular, and stress indicators were assessed throughout the study. At necropsy, 9th to 12th rib sections (four-rib), internal organs, and feet were assessed, and sartorius muscles were collected for ex vivo glucose metabolic studies. Heat stress increased (P < 0.05) rectal temperatures and respiration rates throughout the study and reduced (P < 0.05) weight gain and feed efficiency over the first week, ultrasonic loin-eye area and loin depth near the end of the study, and four-rib weight at necropsy. Fat content of the four-rib and loin were also reduced (P < 0.05) by heat stress. Ractopamine increased (P < 0.05) loin weight and fat content and partially moderated the impact of heat stress on rectal temperature and four-rib weight. Heat stress reduced (P < 0.05) spleen weight, increased (P < 0.05) adrenal and lung weights, and was associated with hoof wall overgrowth but not organ lesions. Ractopamine did not affect any measured indicators of well-being. Heat stress reduced (P < 0.05) blood urea nitrogen and increased (P < 0.05) circulating monocytes, granulocytes, and total white blood cells as well as epinephrine, TNFα, cholesterol, and triglycerides. Cortisol and insulin were not affected. Heat stress reduced (P < 0.05) blood pressure and heart rates in all lambs and increased (P < 0.05) left ventricular wall thickness in unsupplemented but not ractopamine-supplemented lambs. No cardiac arrhythmias were observed. Muscle glucose uptake did not differ among groups, but insulin-stimulated glucose oxidation was reduced (P < 0.05) in muscle from heat-stressed lambs. These findings demonstrate that heat stress impairs growth, metabolism, and well-being even when the impact of feed intake is eliminated by pair-feeding and that systemic inflammation and hypercatecholaminemia likely contribute to these deficits. Moreover, ractopamine improved muscle growth indicators without worsening the effects of heat stress.

Hypertrophic muscle growth and metabolic efficiency were impaired by chronic heat stress, improved by zilpaterol supplementation, and not affected by ractopamine supplementation in feedlot lambs1

Feedlot performance is reduced by heat stress and improved by β adrenergic agonists (βAA). However, the physiological mechanisms underlying these outcomes are not well characterized, and anecdotal reports suggest that βAA may confound the effects of heat stress on wellbeing. Thus, we sought to determine how heat stress and βAA affect growth, metabolic efficiency, and health indicators in lambs on a feedlot diet. Wethers (38.6 ± 1.9 kg) were housed under thermoneutral (controls; n = 25) or heat stress (n = 24) conditions for 21 d. In a 2 × 3 factorial, their diets contained no supplement (unsupplemented), ractopamine (β1AA), or zilpaterol (β2AA). Blood was collected on days -3, 3, 9, and 21. On day 22, lambs were harvested and ex vivo skeletal muscle glucose oxidation was determined to gauge metabolic efficiency. Feet and organ tissue damage was assessed by veterinary pathologists. Heat stress reduced (P < 0.05) feed intake by 21%, final bodyweight (BW) by 2.6 kg, and flexor digitorum superficialis (FDS) muscle mass by 5%. β2AA increased (P < 0.05) FDS mass/BW by 9% and average muscle fiber area by 13% compared with unsupplemented lambs. Blood lymphocytes and monocytes were greater (P < 0.05) in heat-stressed lambs, consistent with systemic inflammation. Plasma insulin was 22% greater (P < 0.05) and glucose/insulin was 16% less (P < 0.05) in heat-stressed lambs than controls. Blood plasma urea nitrogen was increased (P < 0.05) by heat stress on day 3 but reduced (P < 0.05) on days 9 and 21. Plasma lipase and lactate dehydrogenase were reduced (P < 0.05) by heat stress. Glucose oxidation was 17% less (P < 0.05) in muscle from heat-stressed lambs compared with controls and 15% greater (P < 0.05) for β2AA-supplemented compared with unsupplemented lambs. Environment and supplement interacted (P < 0.05) for rectal temperature, which was increased (P < 0.05) by heat stress on all days but more so (P < 0.05) in β2AA-supplemented lambs on days 4, 9, and 16. Heat stress increased (P < 0.05) the frequency of hoof wall overgrowth, but βAA did not produce any pathologies. We conclude that reduced performance in heat-stressed lambs was mediated by reduced feed intake, muscle growth, and metabolic efficiency. β2AA increased muscle growth and improved metabolic efficiency by increasing muscle glucose oxidation, but no such effects were observed with ractopamine. Finally, βAA supplementation was not detrimental to health indicators in this study, nor did it worsen the effects of heat stress.

Whole blood transcriptome analysis in feedlot cattle after 35 days of supplementation with a β1-adrenergic agonist

Ractopamine HCl (RHC) is supplemented to feedlot cattle to improve feed efficiency and increase carcass weight. Supplementation of RHC clearly benefits livestock production, but it is of note that the adrenergic system through which it acts is typically associated with stress. The purpose of this study was to identify changes in the transcriptome of whole blood in RHC-supplemented feedlot cattle. We hypothesized that transcripts related to inflammatory processes would be upregulated after 35 days of dietary RHC supplementation. To test this hypothesis, RNA from whole blood collected from 16 cattle before and after supplementation with 300 mg/day of RHC was sequenced using 3' tag-seq. Eight transcripts were differentially expressed (Adjp < 0.10) between pre- and post-supplementation blood samples. Although several of these transcripts including IFI35, TYROBP, and TP53INP1 are associated with inflammation, a systemic dysregulation of inflammatory pathways was not evident. These data provide insight into the response of cattle to RHC supplementation that will direct future studies examining how the transcriptome of whole blood and other tissues responds during acute exposure to RHC and how this supplement mechanistically improves growth performance.

ASAS-SSR Triennnial Reproduction Symposium: Looking Back and Moving Forward-How Reproductive Physiology has Evolved: Fetal origins of impaired muscle growth and metabolic dysfunction: Lessons from the heat-stressed pregnant ewe

Intrauterine growth restriction (IUGR) is the second leading cause of perinatal mortality and predisposes offspring to metabolic disorders at all stages of life. Muscle-centric fetal adaptations reduce growth and yield metabolic parsimony, beneficial for IUGR fetal survival but detrimental to metabolic health after birth. Epidemiological studies have reported that IUGR-born children experience greater prevalence of insulin resistance and obesity, which progresses to diabetes, hypertension, and other metabolic disorders in adulthood that reduce quality of life. Similar adaptive programming in livestock results in decreased birth weights, reduced and inefficient growth, decreased carcass merit, and substantially greater mortality rates prior to maturation. High rates of glucose consumption and metabolic plasticity make skeletal muscle a primary target for nutrient-sparing adaptations in the IUGR fetus, but at the cost of its contribution to proper glucose homeostasis after birth. Identifying the mechanisms underlying IUGR pathophysiology is a fundamental step in developing treatments and interventions to improve outcomes in IUGR-born humans and livestock. In this review, we outline the current knowledge regarding the adaptive restriction of muscle growth and alteration of glucose metabolism that develops in response to progressively exacerbating intrauterine conditions. In addition, we discuss the evidence implicating developmental changes in β adrenergic and inflammatory systems as key mechanisms for dysregulation of these processes. Lastly, we highlight the utility and importance of sheep models in developing this knowledge.

Serum blood metabolite response and evaluation of select organ weight, histology, and cardiac morphology of beef heifers exposed to a dual corticotropin-releasing hormone and vasopressin challenge following supplementation of zilpaterol hydrochloride

The objectives of this study were 1) to determine if supplementation of zilpaterol hydrochloride (ZH) altered select organ weights, histology, and cardiac anatomical features at harvest and 2) to determine if administration of a corticotropin-releasing hormone (CRH) and vasopressin (VP) challenge following 20 d of ZH supplementation altered the blood chemistry profile in cattle. Crossbred heifers ( = 20; 556 ± 7 kg BW) were randomized into 2 treatment groups: 1) control (CON), without ZH, and 2) zilpaterol (ZIL; ZH at 8.33 mg/kg [DM basis] for 20 d). On d 20 of supplementation, heifers were fitted with indwelling jugular catheters. On d 24, starting at 0800 h and continuing until 1600 h, blood samples were collected at 60-min intervals. At 1000 h, heifers received an i.v. bolus of CRH (0.3 µg/kg BW) and VP (1.0 µg/kg BW) to activate the stress axis. Serum was separated and stored at -80°C until analyzed for a large-animal chemistry panel. Following the CRH/VP challenge, heifers were harvested on d 25, 26, and 27 (5, 6, and 7 d after ZH supplementation); BW, HCW, select organ weights, and histology were measured, and a total heart necropsy was performed. A treatment effect ( ≤ 0.02) was observed for Ca, K, creatinine, alkaline phosphatase, and sorbitol dehydrogenase. Zilpaterol-fed heifers had decreased ( ≤ 0.02) concentrations of Ca and K and increased concentrations ( 0.01) of creatinine ( = 0.02) during the CRH/VP challenge when compared to control heifers. Control heifers had greater ( ≤ 0.05) alkaline phosphatase and sorbitol dehydrogenase concentrations when compared with ZIL heifers. A treatment × time interaction ( = 0.02) was observed for P; concentrations were similar between treatments from -2 to 6 h postchallenge, and 7 h postchallenge CON heifers had decreased P. Liver ( = 0.06) and kidney ( = 0.08) weights as a percentage of BW tended ( ≤ 0.08) to be reduced in ZIL heifers. Gross liver weights tended ( = 0.08) to be lower in ZIL heifers. Other organ (heart, lung, adrenals) to BW ratios remained similar ( ≥ 0.41). These data suggest that there are some variations observed between treatments in terms of response to ZH supplementation and the CRH/VP challenge; however, in the environmental conditions of this study, limited variation in blood metabolic responses and organ weights suggests that the supplementation of ZH did not detrimentally alter the physiology of cattle.

National Beef Quality Audit-2016: assessment of cattle hide characteristics, offal condemnations, and carcass traits to determine the quality status of the market cow and bull beef industry

To continue the series that began in 1994, the National Beef Quality Audit (NBQA) – 2016 was conducted to quantify the quality status of the market cow and bull beef sector, as well as determine improvements made in the beef and dairy industry since 2007. The NBQA-2016 was conducted from March through December of 2016, and assessed hide-on carcasses (n = 5,278), chilled carcasses (n = 4,285), heads (n = 5,720), and offal items (n = 4,800) in 18 commercial processing facilities throughout the United States. Beef cattle were predominantly black-hided; 68.0% of beef cows and 67.2% of beef bulls possessed a black hide. Holstein was the predominant type of dairy animal observed. Just over half (56.0%) of the cattle surveyed had no mud contamination on the hide, and when mud was present, 34.1% of cattle only had small amounts. Harvest floor assessments found 44.6% of livers, 23.1% of lungs, 22.3% of hearts, 20.0% of viscera, 8.2% of heads, and 5.9% of tongues were condemned. Liver condemnations were most frequently due to abscess presence. In contrast, contamination was the primary reason for condemnation of all other offal items. Of the cow carcasses surveyed, 17.4% carried a fetus at the time of harvest. As expected, mean carcass weight and loin muscle area values observed for bulls were heavier and larger than cows. The marbling scores represented by cull animal carcasses were most frequently slight and traces amounts. Cow carcasses manifested a greater amount of marbling on average than bull carcasses. The predominant fat color score showed all carcasses surveyed had some level of yellow fat. Only 1.3% of carcasses exhibited signs of arthritic joints. Results of the NBQA-2016 indicate there are areas in which the beef and dairy industries have improved and areas that still need attention to prevent value loss in market cows and bulls.

National Beef Quality Audit - 2016: Survey of carcass characteristics through instrument grading assessments

The instrument grading assessment portion of the National Beef Quality Audit (NBQA) - 2016 allows the unique opportunity to evaluate beef carcass traits over the course of a year. One week of instrument grading data was collected each month from 5 beef processing corporations encompassing 18 facilities from January 2016 through December 2016 ( = 4,544,635 carcasses). Mean USDA yield grade (YG) was 3.1 with 1.37 cm fat thickness (FT), 88.9 cm LM area, 393.6 kg HCW, and 2.1% KPH. Frequency distribution of USDA YG was 9.5% YG 1, 34.6% YG 2, 38.8% YG 3, 14.6% YG 4, and 2.5% YG 5. Increases in HCW and FT since the NBQA-2011 were major contributors to differences in mean YG and the (numerically) increased frequency of YG 3, 4, and 5 carcasses found in the current audit. Mean marbling score was Small, and the distribution of USDA quality grades was 4.2% Prime, 71.4% Choice, 21.7% Select, and 2.7% other. Frequency of carcasses grading Prime on Monday (6.43%) was numerically higher than the average frequency of carcasses grading Prime overall (4.2%). Monthly HCW means were 397.6 kg in January, 397.2 kg in February, 396.5 kg in March, 389.3 kg in April, 384.8 kg in May, 385.0 kg in June, 386.1 kg in July, 394.1 kg in August, 399.1 kg in September, 403.9 kg in October, 406.5 kg in November, and 401.9 kg in December. Monthly mean marbling scores were Small in January, Small in February, Small in March, Small in April, Small in May, Small in June, Small in July, Small in August, Small in September, Small in October, Small in November, and Small in December. Both mean HCW and mean marbling score declined in the months of May and June. The month with the greatest numerical frequency of dark cutters was October (0.74%). Comparison of overall data from in-plant carcass and instrument grading assessments revealed close alignment of information, especially for YG (3.1 for in-plant assessment versus 3.1 for instrument grading) and marbling (Small for in-plant assessment versus Small for instrument grading). These findings allow the beef industry access to the greatest volume of beef value-determining characteristics for the U.S. fed steer and heifer population than ever reported, resulting in potentially more precise targeting of future quality and consistency efforts.

National Beef Quality Audit-2016: In-plant survey of carcass characteristics related to quality, quantity, and value of fed steers and heifers

The National Beef Quality Audit (NBQA)-2016 used in-plant cooler assessments to benchmark the current status of the fed steer and heifer beef industry in the United States. In-plant cooler assessments ( = 9,106 carcasses) were conducted at 30 facilities, where approximately 10% of a single day's production were evaluated for USDA quality grade (QG) and yield grade (YG) factors. Frequencies of evaluated traits were 66.5% steer and 33.4% heifer sex classes and 82.9% native, 15.9% dairy-type, and 1.2% estimated breed types. Mean USDA YG factors were 1.42 cm for adjusted fat thickness, 89.5 cm for LM area, 390.3 kg for HCW, and 1.9% for KPH. Mean USDA YG was 3.1, with a frequency distribution of 9.6% YG 1, 36.7% YG 2, 39.2% YG 3, 12.0% YG 4, and 2.5% YG 5. Mean USDA QG traits were Small for marbling score, A for overall maturity, A55 for lean maturity, and A for skeletal maturity. Mean USDA QG was Select with a frequency distribution of QG of 3.8% Prime, 67.3% Choice, 23.2% Select, and 5.6% lower score. Lower score included dark cutter (1.9%), blood splash (0.1%), and hard bone, which are USDA overall maturity scores of C or older (1.8%). Marbling score distributions were 0.85% Slightly Abundant or greater, 7.63% Moderate, 23.54% Modest, 39.63% Small, 23.62% Slight, and 0.83% Traces or less. Carcasses that were Choice or Select and USDA YG 2 or 3 accounted for 70.7% of the carcasses evaluated. Compared with the previous NBQA, we found a numerical increase in mean USDA YG, USDA QG, adjusted fat thickness, HCW, LM area, and marbling score with an increase in dairy-type carcasses and percentage of carcasses grading USDA Prime and Choice as well as frequency of USDA YG 4 and 5. The findings from this study will be used by all segments of the industry to understand and improve the quality of fed steer and heifer beef that is being produced.

National Beef Quality Audit-2016: Transportation, mobility, live cattle, and carcass assessments of targeted producer-related characteristics that affect value of market cows and bulls, their carcasses, and associated by-products

The National Beef Quality Audit–2016 marks the fourth iteration in a series assessing the quality of live beef and dairy cows and bulls and their carcass counterparts. The objective was to determine the incidence of producer-related defects, and report cattle and carcass traits associated with producer management. Conducted from March through December of 2016, trailers (n = 154), live animals (n = 5,470), hide-on carcasses (n = 5,278), and hide-off hot carcasses (n = 5,510) were surveyed in 18 commercial packing facilities throughout the United States. Cattle were allowed 2.3 m² of trailer space on average during transit indicating some haulers are adhering to industry handling guidelines for trailer space requirements. Of the mixed gender loads arriving at processing facilities, cows and bulls were not segregated on 64.4% of the trailers surveyed. When assessed for mobility, the greatest majority of cattle surveyed were sound. Since the inception of the quality audit series, beef cows have shown substantial improvements in muscle. Today over 90.0% of dairy cows are too light muscled. The mean body condition score for beef animals was 4.7 and for dairy cows and bulls was 2.6 and 3.3, respectively. Dairy cattle were lighter muscled, yet fatter than the dairy cattle surveyed in 2007. Of cattle surveyed, most did not have horns, nor any visible live animal defects. Unbranded hides were observed on 77.3% of cattle. Carcass bruising was seen on 64.1% of cow carcasses and 42.9% of bull carcasses. However, over half of all bruises were identified to only be minor in severity. Nearly all cattle (98.4%) were free of visible injection-site lesions. Current results suggest improvements have been made in cattle and meat quality in the cow and bull sector. Furthermore, the results provide guidance for continued educational and research efforts for improving market cow and bull beef quality.

The metabolic, stress axis, and hematology response of zilpaterol hydrochloride supplemented beef heifers when exposed to a dual corticotropin-releasing hormone and vasopressin challenge

The objective of this study was to determine the metabolic, stress, and hematology response of beef heifers supplemented with zilpaterol hydrochloride (ZH) when exposed to an endocrine stress challenge. Heifers ( = 20; 556 ± 7 kg BW) were randomized into 2 treatment groups: 1) control (CON), no ZH supplementation, 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 corticotropin-releasing hormone (CRH; 0.3 µg/kg BW) and arginine vasopressin (VP; 1.0 µg/kg BW) to activate the stress axis. Blood samples were collected at 30-min intervals for serum and 60-min intervals for plasma and whole blood, from -2 to 8 h relative to the challenge at 0 h (1000 h). Samples were analyzed for glucose, insulin, NEFA, blood urea nitrogen (BUN), cortisol, epinephrine, norepinephrine, and complete blood cell counts. Following the challenge, cattle were harvested over a 3-d period. Liver, LM, and biceps femoris (BF) samples were collected and analyzed for glucose, lactate, and glycolytic potential (GP). There was a treatment ( ≤ 0.001) effect for vaginal temperature (VT), with ZIL having a 0.1°C decrease in VT when compared with CON. A treatment × time effect ( = 0.002) was observed for NEFA. A treatment effect was observed for BUN; ZIL had decreased BUN concentrations compared with CON ( < 0.001) prior to the challenge; however, no treatment × time effect was observed. There was also a treatment effect for cortisol ( ≤ 0.01) and epinephrine ( = 0.003); ZIL had decreased cortisol and epinephrine during the CRH/VP challenge when compared with CON. There was a time effect for total white blood cells, lymphocytes, and monocytes; each variable increased ( ≤ 0.01) 2 h postchallenge. Additionally, neutrophil counts decreased ( ≤ 0.01) in response to CRH/VP challenge in both treatment groups. Glucose concentrations within the LM were greater ( = 0.03) in CON when compared with ZIL. Lactate concentrations and GP within the BF were greater in CON ( = 0.05) when compared with ZIL. These data suggest there are some variations observed between treatments in terms of response to the CRH/VP challenge; however, in the environmental conditions of this trial, none of the variations observed suggest that the supplementation of ZH detrimentally alters the ability of cattle to effectively respond to stressful stimuli.

National Beef Quality Audit-2016: Transportation, mobility, and harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and by-products

The National Beef Quality Audit-2016 (NBQA-2016) was conducted to assess current transportation, mobility, and quality characteristics of U.S. fed steers and heifers. Data were collected at 17 beef processing facilities between March and November 2016. About 8,000 live cattle were evaluated for transportation and mobility, and about 25,000 carcasses were evaluated on the slaughter floor. Cattle were in transit to the slaughter facility for a mean duration of 2.7 h from a mean distance of 218.5 km using trailers with dimensions ranging from 17.84 m² to 59.09 m². Area allotted per animal averaged 1.13 m² and ranged from 0.85 m² to 2.28 m². A total of 96.8% of cattle received a mobility score of 1 (walks easily, no apparent lameness). Identification types (35.1% had multiple) were lot visual tags (61.5%), individual tags (55.0%), electronic tags (16.9%), metal-clip tags (9.2%), bar-coded tags (0.05%), wattles (0.01%), and other (2.6%). Cattle were black-hided (57.8%), Holstein (20.4%), red-hided (10.5%), yellow-hided (4.8%), gray-hided (2.9%), brown-hided (1.3%), and white-hided (1.1%). Unbranded hides were observed on 74.3% of cattle; 18.6% had brands located on the butt, 6.3% on the side, and 1.3% on the shoulder (values exceed 100% due to multiple brands). For hide-on carcasses, 37.7% displayed no mud or manure; specific locations for mud or manure were legs (40.8%), belly (33.0%), tail region (15.5%), side (6.8%), and top-line (3.9%). Cattle without horns represented 83.3% of the sample, and cattle that did have horns measured: < 2.54 cm (5.5%), 2.54 to 12.7 cm (8.3%), and > 12.7 cm (2.9%). Carcasses without bruises represented 61.1% of those sampled, whereas 28.2% had 1, 8.2% had 2, 2.1% had 3, and 0.3% had 4 bruises. Of those carcasses with a bruise, the bruise was located on the loin (29.7%), round (27.8%), chuck (16.4%), rib (14.4%), and brisket/plate/flank (11.6%). Frequencies of offal condemnations were livers (30.8%), lungs (18.2%), viscera (16.3%), hearts (11.1%), heads (2.7%), and tongues (2.0%). Compared to NBQA-2011, fewer cattle were identified for traceability, fewer were black-hided, a greater number were Holstein cattle, more with no brand and no horns, fewer without bruises, more liver, lung, and viscera condemnations, and fewer heads and tongues were condemned. The NBQA remains an influential survey for the U.S. beef industry to provide benchmarks and strategic plans for continued improvement of beef quality and consistency.

Use of a novel oleaginous microorganism as a potential source of lipids for weanling pigs. Transl Anim Sci 2017;1:201-207. [PMID: 32704643 PMCID: PMC7250434 DOI: 10.2527/tas2017.0023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Weanling pigs are at risk of succumbing to illness due to an immature immune system and insufficient supply of available energy at the time of weaning. This study was aimed at determining whether oleaginous bacteria could serve as a source of lipids to weanling pigs. Weanling pigs were provided a daily dose of 1×10⁹ colony fomring unit (CFU) = kg⁻¹ of the novel oleaginous Enterobacter cloacae strain JD6301 or JD8715 (which is a variant form of JD6301 capable of producing extracellular triglycerides) via oral gavage for 5 d. Serum was collected every 6 h and intestinal samples were collected at 6 d. Providing pigs with JD6301 or JD8715 significantly increased serum concentrations of triglycerides and non-esterified fatty acids (NEFA) within 72 h. Additionally, the JD6301 and JD8715 strains were able to survive within the gastrointestinal tract throughout the duration of the study. These results suggest that providing Enterobacter cloacae can increase the serum lipids in the pigs, thus potentially providing an additional source of energy to animals during times of stress. This could potentially help improve the metabolic response of animals during times of stress.

Cattle temperament influences metabolism: metabolic response to glucose tolerance and insulin sensitivity tests in beef steers

Cattle temperament, defined as the reactivity of cattle to humans or novel environments, can greatly influence several physiological systems in the body, including immunity, stress, and most recently discovered, metabolism. Greater circulating concentrations of nonesterified fatty acids (NEFAs) found in temperamental cattle suggest that temperamental cattle are metabolically different than calm cattle. Further, elevated NEFA concentrations have been reported to influence insulin sensitivity. Therefore, the objective of this study was to determine whether cattle temperament would influence the metabolic response to a glucose tolerance test (GTT) and insulin sensitivity test (IST). Angus-cross steers (16 calm and 15 temperamental; 216 ± 6 kg BW) were selected based on temperament score measured at weaning. On day 1, steers were moved into indoor stanchions to allow measurement of individual ad libitum feed intake. On day 6, steers were fitted with indwelling rectal temperature probes and jugular catheters. At 9 AM on day 7, steers received the GTT (0.5-mL/kg BW of a 50% dextrose solution), and at 2 PM on day 7, steers received the IST (2.5 IU bovine insulin/kg BW). Blood samples were collected and serum isolated at -60, -45, -30, -15, 0, 10, 20, 30, 45, 60, 90, 120, and 150 min relative to each challenge. Serum was stored at -80°C until analyzed for cortisol, glucose, NEFA, and blood urea nitrogen concentrations. All variables changed over time (P < 0.01). For the duration of the study, temperamental steers maintained greater (P < 0.01) serum NEFA and less (P ≤ 0.01) serum blood urea nitrogen and insulin sensitivity (calculated using Revised Quantitative Insulin Sensitivity Check Index) compared with calm steers. During the GTT, temperamental steers had greater (P < 0.01) serum glucose, yet decreased (P = 0.03) serum insulin and (P < 0.01) serum insulin: serum glucose compared to calm cattle. During the IST, temperamental steers had greater (P < 0.01) serum insulin and a greater (P < 0.01) serum insulin: serum glucose as compared with calm steers. These data demonstrate that differences exist in the manner in which temperamental steers respond to glucose and insulin, potentially a result of elevated serum NEFA concentrations, which may result in changes in utilization and redistribution of energy in temperamental vs calm cattle.

Dehydrated citrus pulp alters feedlot performance of crossbred heifers during the receiving period and modulates serum metabolite concentrations before and after an endotoxin challenge

English × Continental heifers ( = 180) were sourced in 2 loads (219.3 ± 16.0 and 221.4 ± 16.4 kg, respectively) from commercial auction barns to study the effects of feeding dehydrated citrus pulp (DCP) on feedlot performance of newly received heifers. A completely randomized block design was used with BW nested within arrival load and blocked by BW into 3 dietary treatments (36 pens, 5 heifers/pen, 12 blocks, 3 pens/block, and 12 pens/treatment). Treatment diets contained 1) 0% DCP (control diet [CON]), 2) 10% DCP, or 3) 20% DCP on a DM basis. Diets containing DCP were exchanged with steam-flaked corn on a 1:1 basis. Cattle were fed a 63, 73, and 83% concentrate diet from d 0 to 28, d 28 to 42, and d 42 to 56, respectively. Over the 56-d trial period, as the amount of dietary DCP increased, DMI decreased ( = 0.01), ADG decreased ( < 0.01), and G:F decreased ( = 0.02). From d 0 to 28, there was no difference in the observed minus the predicted NEg of the diet ( = 0.73); from d 28 to 42, there was a linear increase in NEg favoring DCP treatments ( < 0.01); and from d 42 to 56, there was a linear decrease in NEg against the DCP treatments ( < 0.01). At the conclusion of the trial, a subset of heifers ( = 22; 307.89 ± 3.32 kg on d 63) were used to evaluate blood metabolite concentrations before and after a lipopolysaccharide (LPS) challenge. On d 63, heifers were fitted with jugular catheters and moved into individual stalls. On d 64, heifers were intravenously challenged with LPS (0.5 μg/kg BW), and blood samples were collected every 0.5 h from -2 to 8 h and at 24 h relative to the LPS challenge (0 h). Serum glucose, serum urea nitrogen (SUN), and NEFA concentrations were determined. Cattle lost less weight at both 24 and 72 h after the LPS challenge with increasing DCP percentage ( < 0.01). Glucose ( = 0.12) and NEFA ( = 0.13) concentrations did not differ before the LPS challenge; however, there was a treatment effect for SUN, with elevated concentrations of SUN in CON cattle ( < 0.01). After the LPS challenge, DCP-fed cattle had reduced glucose, elevated NEFA, and reduced SUN concentrations ( ≤ 0.01). Results indicate that dietary DCP modulated metabolite concentrations in heifers following an endotoxin challenge and affected feedlot performance when incorporated in receiving diets in replacement of corn. Future studies will need to address strategies to increase DMI or explore levels of DCP less than 10% in the diet of newly received heifer calves.

The Role of Direct-Fed Microbials in Conventional Livestock Production

Supplementation of direct-fed microbials (DFM) as a means to improve the health and performance of livestock has generated significant interest over the past 15+ years. A driving force for this increased interest in DFM is to reduce or eliminate the use of low-dose antibiotics in livestock production. This increased attention toward DFM supplementation has generated an extensive body of research. This effort has resulted in conflicting reports. Although there has been considerable variation in the design of these studies, one of the main causes for this lack of consistency may be attributed to the variation in the experimental immune challenge incorporated to evaluate DFM supplementation. Taking into account the experimental immune challenge, there is strong evidence to suggest that DFM supplementation may have an impact on the immune response, overall health, and performance of livestock.

Exogenous administration of lipids to steers alters aspects of the innate immune response to endotoxin challenge

This study examined the effects of increasing energy availability from both dextrose and lipid treatments on the pro-inflammatory response to LPS in Holstein steers. Steers were randomly assigned to one of three groups: saline at 0.5 ml/kg body weight (Control) or 50% dextrose [0.5 ml/kg body weight (Dextrose) to mimic calm cattle’s response to LPS] administered immediately prior to LPS (0.5 µg/kg body weight at 0 h) or continuous lipid emulsion infusion from −1 to 6 h [Intralipid 20% (Baxter, Deerfield, IL USA); 0.5 ml/kg/hr (Lipid) to mimic temperamental cattle]. Concentrations of non-esterified fatty acids (NEFA) were greater in Lipid compared with Control and Dextrose steers. A greater decrease in the change in rectal temperature, relative to baseline, was observed in response to LPS in Dextrose in comparison to control and Lipid steers. Cortisol was greater in Lipid than Dextrose and Control steers from −0.5 to 0 h, yet decreased from 0.5 to 5.5 h relative to LPS challenge. Concentrations of IL-6 were decreased in Lipid steers compared with Dextrose and Control steers, and were decreased in Dextrose compared with Control steers post-LPS challenge. These data suggest that increasing circulating NEFA using an exogenous Lipid emulsion may modulate the pro-inflammatory response in steers.