Abstract Lubabegron (LUB; Experior®; Elanco Animal Health, Greenfield, IN), a β-adrenergic modulator, is the first U.S. Food and Drug Administration approved product that reduces ammonia gas emissions per kilogram of live weight and hot carcass weight in beef steers and heifers fed in confinement for slaughter. However, there is limited information about the effect of LUB on nitrogen retention, skeletal muscle turnover, and glucose metabolism in beef cattle. Therefore, 16 Angus steers (initial BW = 553 ± 25 kg) were used in a randomized complete-block-design to examine the impact of LUB feeding on apparent nitrogen retention and excretion, fractional degradation rate of skeletal muscle, and glucose tolerance. Steers were individually housed in outdoor dirt-surfaced pens and fed a steam-flaked corn-based diet once daily in amounts to allow ad libitum access to feed over a 24 h period. Treatments were negative control (CON; no β-ligand) and LUB (fed at a rate of 3.2 g Experior/ ton of DM for the last 91 d on feed). A glucose tolerance test (GTT) was conducted twice during the study, and total fecal and urinary output were collected for 5 d on all steers. On day 96, following a 4-day LUB withdrawal period, all animals were slaughtered at a USDA-inspected abattoir, and carcass data were collected. Data were analyzed using the mixed models procedure in R. Initial and final body weights, dry matter intake, average daily gain, and feed efficiency were similar (P > 0.05) between treatments. Skeletal muscle degradation and fractional protein breakdown rate were reduced (P < 0.01) when cattle fed LUB were compared to cattle fed CON. Neither treatment nor a treatment × time interaction influenced glucose, insulin, or non-esterified fatty acids concentrations throughout the GTT. Apparent nitrogen absorption and retention were not different across treatments (P > 0.05), but total urinary output was reduced (P = 0.02) when cattle were fed LUB. Steers receiving LUB had a 9.21% reduction (P = 0.004) in calculated cumulative ammonia gas emissions compared with control steers. Longissimus muscle (LM) area was greater (P < 0.01) in steers fed LUB compared to steers fed CON, whereas yield grade tended (P = 0.09) to be greater in steers fed CON than in steers fed LUB. These results indicate that LUB supplementation decreased muscle protein turnover, improved LM area, and reduced total urinary output in feedlot cattle, without affecting nitrogen balance.
Abstract The size and density of feather follicles are important appearance quality traits for slaughtered broilers. In China, consumers generally prefer broilers with smooth skin and fine follicles, yet the genetic and molecular basis of these traits remains poorly understood. In this study, we characterized feather and feather follicle traits in 589 yellow-feathered chickens at 100 days of age and investigated candidate genes and SNPs associated with feather follicle size. Skin microscopy combined with image analysis provided a practical approach for quantifying follicle size. The size of feather follicles, the weight, length, and diameter of feathers were significantly higher in males than in females (P < 0.05), indicating clear sexual dimorphism. Feather follicle traits also showed greater variation than feather traits, which may limit the efficiency of direct selection. Correlation analysis showed a higher genetic association between dorsal feather length and follicle size of dorsopelvic tract, suggesting the potential for indirect selection of feather follicle size. RNA sequencing of large and small feather follicle tissues identified 1,273 differentially expressed genes. These differentially expressed genes were primarily enriched in the Wnt, MAPK, calcium, and TGF-β signaling pathways. Further analysis identified several HOX family genes, including HOXC10, HOXD11, HOXB3 and HOXD12, which may play crucial roles in feather follicle development. The tissue expression profile indicates that the HOXB3 gene is highly expressed in skin tissue. Polymorphism analysis of HOXB3 identified 3 SNPs significantly associated with feather follicle size (P < 0.05). These findings provide a practical method for follicle-size measurement and identify candidate pathways, genes, and SNP markers for the genetic improvement of feather follicle traits in chickens.
Abstract This study evaluated the effects of supplementation of a Bacillus-based direct-fed microbial (DFM) on the plasma metabolome and fecal microbiome of multiparous beef cow-calf pairs. On day 0 (94 ± 19 days prepartum), 296 Brangus crossbred beef cows were randomly assigned to treatments consisting of free-choice access to a trace mineral supplement alone (CON) or combined (BAC) with Bacillus subtilis 810 and B. licheniformis 809 (3 g/head/day; 6.6 × 109 CFU/head/day) from day 0 to 330 (weaning). Blood was collected from cows on days 0, 30, and 60, and from calves at birth, day 150, and day 330 for targeted metabolomics. Fecal samples were collected from cows on days 0, 60, 150, and 330, and from calves on days 150 and 330 for 16S rRNA gene sequencing. On day 30, BAC cows had greater (P ≤ 0.05) plasma concentrations of seven conjugated bile acids and two ceramides, but reduced (P ≤ 0.05) isoleucine, 3-indoleacetic acid, and indoxyl sulfate, with 12 pathways upregulated and 3 downregulated. On day 60, BAC cows had greater (P ≤ 0.05) total diacylglycerol and select diacylglycerol and triacylglycerol species, but reduced (P ≤ 0.05) eicosapentaenoic acid (EPA) and polyunsaturated phosphatidylcholines, with 11 pathways downregulated. Treatment effects were not detected (P ≥ 0.14) for fecal bacterial phyla, genera, or alpha diversity in cows, except for greater (P ≤ 0.04) Clostridium butyricum and C. alkalicellulosi relative abundances in BAC vs. CON cows at weaning. In calves, 103 metabolic pathways were impacted at birth (P ≤ 0.05), with the most upregulated being alanine, aspartate, and glutamate metabolism pathways; BAC calves also had greater (P ≤ 0.04) plasma alanine, aspartate, proline, and EPA concentrations at birth. At day 150, BAC calves exhibited greater total triacylglycerol concentrations (P = 0.01) across 48 individual species and upregulation of MIF-mediated immune regulation pathways. At weaning (day 330), BAC calves had greater (P ≤ 0.05) plasma anserine and select triacylglycerols, but reduced (P ≤ 0.05) ceramides and tended to have reduced (P ≤ 0.10) branched-chain amino acids, with 17 metabolic pathways downregulated. These findings indicate that gestation-to-weaning Bacillus-based DFM supplementation altered the plasma metabolome of beef cow-calf pairs, with limited effects on the fecal microbiome, and these changes coincided with the previously reported improvements in calf preweaning growth, post-weaning immune response, and carcass quality.
Abstract This study evaluated genomic variance components, genomic heritability, fixed effects, and the predictive performance of genomic best linear unbiased prediction (GBLUP) for body length, chest depth, heart girth, withers height, and body weight in 553 Awassi sheep genotyped using a high-density single nucleotide polymorphism (SNP) panel. Following quality control, 515,358 SNPs were retained to construct the genomic relationship matrix (GRM). Genomic heritability estimates varied across traits, ranging from 0.221 for body weight to 0.733 for body length, with comparatively high estimates also observed for heart girth and withers height. Birth type, animal age, and sex significantly affected all evaluated traits, whereas parity did not. Repeated five-fold cross-validation demonstrated low-to-moderate within-population genomic predictive ability, with the highest predictive performance observed for body length and withers height and the lowest for body weight. GBLUP consistently improved phenotypic prediction compared with fixed-effects-only models, although reductions in prediction error were modest. Prediction accuracies derived from full-data prediction error variance (PEV) were higher than cross-validated predictive ability. They were therefore interpreted as model-based accuracy measures rather than independent validation results. Overall, the findings demonstrate that genomic information can contribute to the prediction of body measurements and weight traits in Awassi sheep. However, broader implementation in genomic selection programs will require larger, multi-flock reference populations and independent or relationship-blocked validation to establish the robustness and transferability of predictive performance.
Abstract The thermal Efficiency Index (TEI) estimated through infrared thermography has been used to predict metabolic efficiency in pigs. This study evaluated the effect of thermal efficiency on growth performance, feed efficiency, feeding pattern, and carcass characteristics of grow-finish pigs. It was hypothesized that high TEI pigs lose more energy as radiant heat and leaving less energy available for growth, whereas low TEI pigs lose less energy as heat, allowing more energy to be partitioned toward growth. Eight-week-old pigs (N = 176) were enrolled in a 12-week experiment, with 88 pigs per block (replicated once over time) under a randomized complete block design. At nursery exit, pigs were scanned using an infrared camera and mean dorsal surface temperature was recorded and used to calculate TEI (dorsal temperature divided by metabolic body weight, BW^0.75). In each block, 44 pigs were selected into high (HIGH; TEI: 4.29 ± 0.39; body weight 15.62 ± 1.43kg) and low (LOW; TEI: 3.48 ± 0.35; body weight 20.28 ± 1.82kg) TEI categories, and group housed separately (11 pigs/ pen). The study was partitioned into three phases: Grower (10-12 weeks), Finisher 1 (12-16 weeks), and Finisher 2 (16-20 weeks). Growth performance, feed intake, and feeding patterns were recorded for each pig individually and calculated by phase. LOW pigs showed greater average daily gain (p = 0.01) and final body weight (p < 0.01) than HIGH pigs. Feed efficiency indices did not differ during early phases but in Finisher 2, LOW pigs had higher residual intake and gain (p < 0.003) and tended to have lower residual feed intake (p = 0.076). For feeding patterns, LOW pigs showed fewer visits, longer feeding duration, and higher feeding rates (p < 0.001). Carcass backfat was also greater in LOW pigs (p = 0.018). Collectively, these findings demonstrate that TEI is closely related to growth efficiency that reflects differences in energy retention and heat energy dissipation and the advantage in feed efficiency is more pronounced in the late finishing phase.
