Journal of animal science最新文献

{"title":"PS12-2. Lipopolysaccharide (LPS) Challenge Alters Oxidative Stress Markers in Dairy-beef Breeds.","authors":"Sam Barker, Joshua Slay, Mackenzie M Smithyman, Nicole C Burdick Sanchez, Paul R Broadway, Ryan R Rathmann, Michael A Ballou, Jerrad Legako","doi":"10.1093/jas/skag272.348","DOIUrl":"https://doi.org/10.1093/jas/skag272.348","url":null,"abstract":"The objective of this study was to evaluate dairy cross-breeding influence on oxidative stress incurred when subjected to a lipopolysaccharide (LPS) challenge. Steers (n = 30; 194 kg ± 40 kg) were transported to the USDA- Livestock Issues Research Unit where they were housed in individual pens with ad libitum access to a receiving ration and water. Breed differences were established as crossbred beef steers (NAT; n = 9), Charolais × Jersey crossbred steers (CHAR; n = 10), and Holstein × Angus crossbred steers (HOL; n = 11). Steers were fitted with jugular catheters and indwelling rectal thermometers on d -1. On d 0, steers were challenged i.v. with LPS (0.15 μg/kg BW) and blood samples were collected at -2, 0, 1, 2, 4, 6, 8, 12, 24, 36, and 48 h relative to administration of LPS. Blood was further processed for plasma and analyzed for lipid oxidation via thiobarbituric reactive substance (TBARS) and total antioxidant capacity (TAC). Data were analyzed as a repeated measure using the GLIMMIX procedure of SAS. There was a breed effect on malondialdehye (MDA) concentrations via TBARS (P = 0.05), where concentrations were lowest in NAT steers when compared to HOL (P = 0.02) and CHAR (P = 0.06). There was a main effect of time on MDA (P < 0.001), where concentrations reached their lowest at 2 h post-challenge, but increased after 4 h (P < 0.001), where concentrations were then similar from 6 h until 36 h (P ≥ 0.05). From 36 to 48 h post-challenge, concentrations decrease again to levels similar to those at h 2 (P ≥ 0.12). An interaction occurred between breed type and time for TAC (P = 0.03). By 6 h, CHAR had the greatest TAC compared to NAT (P = 0.03) and HOL (P = 0.06). This continued to 8 h, where CHAR had a greater TAC compared to NAT (P = 0.04). These data suggest that breed type may influence the ability to manage oxidative stress during an immune challenge, which can have further impacts on feedlot performance, management practices, and meat quality as terminal breeds.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"1 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"265. Influence of Timing of Grazing During the Growing Season on Forage Utilization, Foraging Efficiency, Botanical Composition, and Diet Quality in Semi-arid Rangelands.","authors":"Cooper W Simmons, Caroline W Gatschet, Noah G Davis, Kaylen Stearns, Gavin Haines, Tucker L Lytton, Sophie O'Connor, Kylee Lewis, Annika Anderson, Paul W Nugent, Brett W Griesbaum, Tim DelCurto, Sam Wyffels","doi":"10.1093/jas/skag272.118","DOIUrl":"https://doi.org/10.1093/jas/skag272.118","url":null,"abstract":"Current grazing management recommendations for foothill bunchgrass rangelands include deferring grazing during the growing season to allow forage recovery from defoliation on an every-other-year or a two out of every-three-year basis. Although research supports that deferment during the growing season is fundamental to maintaining sustainable grazing systems, there is limited information on how grazing behavior changes throughout the growing season. Therefore, our objectives were to evaluate the impacts of grazing timing during the growing season on diet quality, botanical composition of diet, and foraging behavior of beef cattle grazing on semi-arid, bunchgrass-dominated rangelands. In 2024 and 2025, we utilized sixteen ruminally-cannulated cattle in a complete randomized block design with 16 four-hectare pastures (four blocks, each containing four pastures). Four grazing treatments were randomly assigned within each block: 1) early season (mid-May to early June), 2) mid-season (early June to late June), 3) late season (late June to mid-July), and 4) ungrazed control pastures. At the initiation of each grazing treatment, six ruminally-evacuated cannulated cows were observed grazing for 20 minutes to collect bite counts by species. Rumen diet samples were collected from the grazing bouts to evaluate foraging behavior, diet composition, and diet quality. Pastures were clipped to assess forage production by functional group and potential regrowth. For foraging behavior, grams consumed per minute and bites per minute displayed a treatment × year interaction (P ≤ 0.03). Where grams consumed per minute displayed a quadratic pattern in year two and bites consumed per minute displayed a quadratic pattern in year one (P = 0.02) and a linear pattern in year two (P = 0.01). Grams/bite differed among treatments (P = 0.04), linearly increasing as the grazing season progressed (P < 0.01). In both years, grass composition of the diet decreased linearly (P < 0.01) as the growing season progressed. Conversely, forb composition of the diet increased linearly (P < 0.01) both years. Dietary crude protein displayed a treatment × year interaction, where it linearly decreased in year one (P < 0.01) and quadratically decreased in year two (P < 0.01). Relative preference in the diet for both grass and forbs displayed treatment × year interactions (P < 0.01), where preference for grass linearly decreased both years (P < 0.01), and relative preference for forbs linearly increased in year one (P < 0.01). In summary, grazing behavior and diet composition differed across time throughout the growing season. This suggests that as the season progresses, cattle alter their foraging strategy to optimize nutrient intake. Grass-to-forb ratio of the diet, diet quality, and foraging behavior, as a function of grazing timing within the growing season, reflect the changing foraging strategies as the growing season progresses.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"22 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"139. Award Talk: Integrative Physiology and Functional Genomics Reveal Novel Mechanisms Regulating Pubertal Development in Gilts.","authors":"Clay A Lents, Hiruni R Wijesena, Dan J Nonneman, Brittney N Keel, Gary A Rohrer, Casey C Nestor, Tad S Sonstegard, Stan M Hileman, Brett R White","doi":"10.1093/jas/skag272.189","DOIUrl":"https://doi.org/10.1093/jas/skag272.189","url":null,"abstract":"Gilts reaching puberty early have greater lifetime productivity but 10-20% are acyclic before first breeding, presenting a major management challenge. Puberty is a complex maturational process, involving molecular and cellular events that are influenced by the environment, nutrition, and genetics. Initiation of puberty results from increasing episodic release of GnRH from the hypothalamus that drives increased pulsatile secretion of LH from the anterior pituitary gland. Through classical endocrine studies and precision gene editing we have shown that kisspeptin is a master regulator of gonadotropin secretion in pigs and is essential for puberty. Virtually all hypothalamic kisspeptin neurons in the pig coexpress neurokinin B and dynorphin (KNDy neurons). These KNDy neurons are thought to regulate GnRH release in an auto/paracrine fashion and kisspeptin knockout pigs have been used to demonstrate this. We have described the spatial organization of KNDy cells and related receptors within the gilt hypothalamus that show similarities to other species and differences unique to pigs. Pubertal development and acyclicity in gilts have been linked to developmental changes in KNDy expression. We have shown how KNDy cells and functions are affected by nutrition and steroid feedback. Because age at puberty is the earliest indicator of future reproductive potential of a gilt and because it is moderately heritable, identification of genomic markers can support marker-assisted selection to improve gilt development. Loci on Sus scrofa chromosomes (SCC) 1, 2, 9, and 14, identified through genome-wide association studies (GWAS) reveal age at first estrus is polygenic, controlled by many genes with small effects (typical allelic affects between 1-2 d). Several QTL associated with age at first estrus in gilts contain candidate genes associated with age at menarche in humans (RORA, AQP8, ANGPT2) and that overlap with correlated human traits of body mass index, height, and obesity (e.g., CRCT1, ADAMTSL3). GWAS for age at puberty in gilts identified genes associated with gonadotropin hormones (NHLH2, TAC1, LHX6, FOXD1, CABP7), and ovarian function (PAPPA, IGF1R, ESSRG, SLIT2, CRTC1). The QTL on SSC2 harbored putative olfactory receptor genes (OR2M4) necessary for response to boars and we showed that stage of the estrous cycle has large effects on expression of putative olfactory receptors in the olfactory epithelium of gilts. Several QTL contained candidate genes with pleotropic effects on traits of reproduction (GAS2L1, MEF2C, LIF), and growth and metabolism (ACACA, PIAS1, FEM1B, NUCB2). Treating gilts with Nesfatin-1 (NUCB2 gene) altered feed intake and increased LH release, demonstrating biological function of this puberty linked gene. Putative functional polymorphisms (94 variants in 33 genes) associated with age at puberty have been identified with fine SNP mapping and, more recently, imputation to whole genome sequence. Functional variants in genes related to soci","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"33 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PS1-28. Validation of an Method to Determine Individual Grazing Dry Matter Intake at Scale in Beef Cattle.","authors":"Addison Geyer, Tylor J Yost, E K ArunKumar, Nathan Blake, Ida Holaskova, Matthew E Wilson","doi":"10.1093/jas/skag272.574","DOIUrl":"https://doi.org/10.1093/jas/skag272.574","url":null,"abstract":"Knowing the accurate dry matter intake (DMI) is vital in order for cattle farmers to optimize farm management. DMI is affected by various factors including forage quality, environmental conditions, and individual animal characteristics. This study aims to validate an AI tool that can predict individual, daily DMI to identify efficient animals from prospective herd replacements. The data was collected from a sample of one hundred thirteen beef females over a period of fifty days. Variables measured include forage nutrient composition, pasture biomass, animal-specific characteristics (including bodyweight and breed), individual water intake, and environmental parameters (such as temperature and humidity). Weather data includes hourly dry bulb temperature, precipitation, relative humidity, station pressure, and wind speed which were all collected from NOAA stations located near the research site. DMI was determined using body weight, water intake and climatic variables. Ground truth DMI was determined by providing 20 g/day titanium dioxide for six days and collecting fecal samples twice a day for the last three days. Given the amount of titanium dioxide in feces, the DMI was determined and measured. The RMSE of determined and ground truth DMI for the days that both were determined was 1.35 kg. The AI tool appears to be a very good measure of individual, daily DMI for this external validation dataset. These results created an approach to determining feed intake in cattle that captures interaction between the environment and animal.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"1 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"171. Feed Smarter: Bacillus Based Direct Fed Microbial Supplementation Improves Feed Intake and Reduces Stress Markers in Feeder Calves.","authors":"Rodrigo Marques","doi":"10.1093/jas/skag272.158","DOIUrl":"https://doi.org/10.1093/jas/skag272.158","url":null,"abstract":"The animal industry faces growing pressure to improve production efficiency and animal health while reducing environmental impacts and ensuring product safety. Within this context, the use of biotics, commonly referred to as probiotics or direct-fed microbials (DFM), has gained increasing attention due to their capacity to enhance nutrient digestion, reduce morbidity and mortality, alleviate stress-related responses, and improve growth performance and feed efficiency. Given these benefits, our research and others have evaluated the effects of supplementing a Bacillus-based DFM (BAC; Bovacillus™; Novonesis, Hørsholm, Denmark) during the most physiologically and nutritionally challenging phases of the beef cattle production cycle, when feeder cattle are exposed to multiple stressors, including weaning, transportation, commingling, and dietary transitions at feedlot entry. Across compiled studies, BAC supplementation in forage based diets or total mixed rations (TMR) was associated with a 3.4% increase in dry matter intake relative to non supplemented cattle. In our initial studies evaluating BAC supplementation in cattle (n = 15) consuming a forage based diet, intake increased by 4% compared with non supplemented cattle (15.5 vs. 14.9 kg/d; P < 0.01). In this study, cattle supplemented with BAC increased DM and CP digestibility by 3.4 and 5.7% compared with CON, respectively. Digestibility of NDF and ADF tended to increase by 2.7 and 2.4%, respectively. In addition, Bacillus based DFM supplementation increased the total amounts of DM, CP, NDF, and ADF digested by 13.6, 16.4, 11.9, and 11.6%, respectively. These results are consistent with the compiled studies, showing increases of 3.9%, 6.5%, and 5.1% in DM, CP, and NDF digestibility, respectively, when cattle are supplemented with BAC. In another study from our group, supplementing BAC during the receiving phase for beef calves (n = 84) tended to increase DMI compared with the CON group (P = 0.06), without affecting other performance parameters (P ≥ 0.50). A treatment × day interaction was observed for plasma cortisol concentration (P < 0.01), with CON animals exhibiting greater cortisol concentrations on d 14. Mean plasma haptoglobin concentration was greater in CON compared with BAC calves (P = 0.03). Collectively, these results indicate that Bacillus based DFM supplementation increased feed intake and nutrient digestibility while reducing circulating stress markers in feeder calves during a receiving period, supporting its potential use as a nutritional strategy during challenging phases of the feeder cattle production cycle.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"55 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149078015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"349. Award Talk: Effects of Betaine Supplementation and Nutrient Restriction During Gestation Onfetal Muscle Development and Oxidative Status in Sheep.","authors":"Santhi Priya Voggu, Nicole M Tillquist, Cheyenne S Summers, Kaitlyn Baran, Nicholas Barnello, Manda S Reiter, Mia Y Kawaida, Sarah A Reed, Steven A Zinn, Kristen E Govoni","doi":"10.1093/jas/skag272.137","DOIUrl":"https://doi.org/10.1093/jas/skag272.137","url":null,"abstract":"Maternal nutritional status during gestation impacts fetal myogenesis and liver oxidative balance, thereby altering growth and metabolic function. Supplementation of betaine, a methyl donor, supports muscle development and antioxidant capacity, and improves physiological responses. We hypothesized that maternal nutrient restriction during gestation would impair fetal muscle development and alter fetal liver antioxidant status, while betaine supplementation would alleviate the negative effects of maternal nutrient restriction. To test this hypothesis, 32 multiparous Dorset ewes were estrus-synchronized and bred to one of three related rams. Ewes pregnant with twins were assigned to one of four diets [100% NRC requirements (CON), 60% NRC (RES), CON+betaine (CON+BET; 2 g/day), and RES+BET] from day 30 to 130 of gestation. The offspring included 27 males (CON:8, RES:5, CON+BET:5, RES+BET:9) and 37 females (CON:8, RES:9, CON+BET:11, RES+BET:9). Maternal blood was collected on days 30 and 130 of gestation, and at necropsy on day 130, fetal semitendinosus (STN) and longissimus dorsi (LM) muscles, and liver were collected for immunohistochemistry and oxidative status, respectively. Malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were measured in maternal plasma and fetal liver isolates using commercially available assay kits. Data were analyzed using RStudio with ANOVA, including fetal sex as a covariate, with P ≤ 0.05 considered significant and 0.05 < P ≤ 0.10 as a tendency. In fetal STN, the percentage of Pax7-positive cells was reduced in RES compared with CON and RES+BET (P ≤ 0.01). In contrast, the percentage of Pax7-positive cells in the LM was not affected by maternal diet (P = 0.65). Male fetuses from RES ewes had greater type I and fewer type II fibers compared with RES+BET males in STN (P = 0.03). Maternal plasma MDA concentration, SOD, and GPx activities did not differ among diet groups at day 30 of gestation (P ≥ 0.20). At day 130, maternal plasma GPx activity tended to be reduced in RES+BET (5.86±1.12 U/mL) compared with CON+BET (10.26±1.28 U/mL; P = 0.08), while MDA and SOD were not different (P ≥ 0.64). Fetal liver SOD and GPx activities were greater in CON (40±1.95 and 74.5±3.55 U/mg protein, respectively) and CON+BET (35.7±2.18 and 77±4.13 U/mg protein) than in RES (27±2.64 and 58±4.16 U/mg protein) and RES+BET (29±1.90 and 63±3.70 U/mg protein; P ≤ 0.001). Fetal liver MDA concentrations were not affected by maternal diet but tended to be greater in males (0.133±0.007 nmol/mg protein) than females (0.114±0.006 nmol/mg protein; P = 0.06). Overall, maternal nutrient restriction altered fetal muscle development and liver antioxidant capacity, with betaine supplementation providing partial, tissue specific responses, highlighting the need for further study of betaine as a targeted nutritional intervention during maternal nutrient restriction.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"17 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"268. Copper Deficiency of Cool-Season Invaded Grassland Affects Liver Mineral Content of Growing Beef Heifers.","authors":"Rachael G Christensen","doi":"10.1093/jas/skag272.125","DOIUrl":"https://doi.org/10.1093/jas/skag272.125","url":null,"abstract":"Yearling beef heifers grazing grasslands often exhibit outward signs of copper (Cu) deficiency, including poor coat color, dulled hair and weakened immune response, indicating inefficiencies in growth and production. We utilized a 2 by 2 factorial study to compare liver mineral concentration and weight gain of yearling heifers (Bos taurus) receiving one of two types of Cu supplement (amino acid complexed copper vs. copper chloride) and grazing on cool-season dominated pastures that were managed two different ways (rested one or more years prior to grazing vs grazed yearly). Three different pastures were split in 4 paddock strips, with two assigned for organic supplementation and two for inorganic supplementation of copper with a group of 3 heifers (blocked by weight) grazing in each sub paddock. Pastures contained primarily smooth bromegrass (Bromus inermis Leyss.), Kentucky bluegrass (Poa pratensis L.), western wheatgrass [ Pascopyrum smithii (Rydb.) A. Liive], needle and thread (Stipa comata Trin. and Rupr.), green needlegrass (S. viridula Trin.), blue grama [Bouteloua gracilis(Willd.ex Kunth) Lag. Ex Griffiths] and upland sedges (Carex spp.). Liver samples were collected before and after grazing the trial pastures for 6 wk. for two years, while due to drought conditions, a smaller group of cattle were grazed the other two years. Therefore, four years of weekly forage samples and biomass data were collected but only two years of biopsied liver, forage and mineral consumption, and weight data. Heifers were supplemented with loose mineral supplying 168 mg Cu hd-1d-1. Liver Cu concentration in the pre-trial sampling averaged 29 ±21.01 mg/g DW for both groups. Post trial liver Cu was increased 35 mg/g DW for heifers receiving amino-acid complexed copper, and 29.8 mg/g DW for those on inorganic sources, but the difference was not significant and was not affected by pasture management (P = 0.56). Forage samples did not demonstrate differences in Cu concentration due to management. There were also no differences in body weight increase between amino acid Cu- supplemented and Cu-chloride supplemented heifers during the grazing season. Average daily gain was significantly different due to year (0.65 kg the first year and 0.46 kg, P = 0.02 the next year) but not affected by copper source or pasture management. The most consistent benefit from Cu supplementation was an increase in liver copper concentration regardless of copper source. Forage values indicate that grassland forages are marginal to deficient in Cu for optimal development of beef heifers and supplementation is necessary, with amino-acid chelated Cu heifers posing a marginally greater Cu content in liver.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"112 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PS6-8. High Fat Milk Replacers Promote Early Marbling Development in Angus X Holstein Calf Ribeyes.","authors":"Perri Gish, Logan Rosenberg, Lucas Smith, Payam Vahmani","doi":"10.1093/jas/skag272.394","DOIUrl":"https://doi.org/10.1093/jas/skag272.394","url":null,"abstract":"Beef-on-dairy calves raised at calf ranches are fed milk replacer during the pre-weaning stage, creating opportunities to promote enhanced muscle and marbling development through early-life nutritional interventions. The objective of this study was to measure how dietary energy source affects skeletal muscle development in beef-on-dairy calves. 16 same-sire Holstein x Angus calves were assigned to either a high-fat (HF, 34% lactose and 30% crude fat) or high-lactose (HL, 50% lactose and 18% crude fat) diet on day 1 of life, and calves were fed their respective milk replacer on a step-up step-down feeding schedule for 50 days. Diets were isonitrogenous and fed at 150g/L (HL) or 132g/L to ensure an isocaloric intake; chopped wheat straw and water were offered ab libitum. Fecal and respiratory scores were taken daily, all feed refusals were measured, and weight was recorded weekly. Calves were slaughtered at 50 ± 3 days of age and the right longissimus thoracis (ribeye) was frozen at -20 °C for later meat quality assessment. Samples from the left ribeye and brisket were flash frozen in liquid nitrogen and stored at -80 °C until cryosectioning. For meat quality assessment, collected ribeyes were thawed in a low cooler until 3 °C and measured using a colorimeter. Warner-Bratzler shear force was performed parallel to muscle fibers on triplicate cooked ribeye cores using a 1000N load cell. For ex vivo histology, flash frozen muscle was cryosectioned transversely and immunohistochemically stained for perilipin-1 to stain mature lipid membranes, PDGFRa to stain fibro-adipogenic progenitor cells (FAP) which predate marbling, and Ki67 to stain proliferating cells. Statistical analysis was performed using an unpaired t-test, and significance was set at p < 0.05 and trends at 0.05< p < 0.1. Both fecal and respiratory scores were not significantly different between treatment groups, and HF and HL calves had similar feed conversion ratios and average daily gains. HF ribeyes were significantly greener than HL, and HF trended to be more yellow in objective color measurement; shear force was not significantly impacted. HF ribeyes had a significantly higher fat:muscle ratio in the ribeye, but in the brisket HL samples has a higher fat:muscle ratio. Despite this finding, we found no significant difference between HL and HF FAP cell counts or their proliferation rates. This preliminary data shows that while health and performance is maintained between isocaloric diets, a dietary energy source of primarily fat promotes early marbling development in a muscle-specific manner within the first 50 days of life. However, the mechanism behind this remains unclear. Future work will further assess pro-meat quality muscle development and the systemic effects of dietary energy source.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"196 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PS1-22. Monensin, Narasin, and Their Alternation in High-concentrate Diets Do Not Accelerate Puberty in F1 (Angus × Nellore) Heifers.","authors":"Larissa Peroti Bello, Bismarck Soares Alexandrino, Mariana Jeronymo, Pedro Henrique de Lima Salmaso, Mirela B Balistrieri Dias, Bárbara Martins Brixner, Daniel Montanher Polizel, Diogo Fleury Azevedo Costa, Flávio Augusto Portela Santos, Alexandre Vaz Pires","doi":"10.1093/jas/skag272.570","DOIUrl":"https://doi.org/10.1093/jas/skag272.570","url":null,"abstract":"Age at puberty and age at first calving are key determinants of efficiency in beef production systems. Earlier reproductive maturity allows heifers to calve sooner and remain productive for a longer period, increasing lifetime productivity. Puberty onset is influenced by the interaction between genetic background and nutritional management during the pre-pubertal growth phase. Nutritional strategies that enhance body development during this stage may contribute to earlier reproductive maturity. In this context, feedlot systems combined with feed additives that improve dietary energy utilization could potentially promote earlier puberty. Therefore, we hypothesized that feedlotting pre-pubertal heifers associated with ionophore supplementation would enhance body development and advance the onset of puberty. Forty F1 (Angus × Nellore) heifers were used in this study. At the beginning of the experiment, animals averaged 210 ± 16.95 kg of body weight and were approximately 8 months of age. Heifers were assigned to a randomized complete block design according to initial body weight. Treatments consisted of: (1) CON = basal diet without additive; (2) MON = CON diet plus 25 ppm monensin; (3) NARA = CON diet plus 13 ppm narasin; and (4) N+M = alternation between narasin (13 ppm) and monensin (25 ppm) at each experimental period. The experimental period lasted 154 days, including 14 days of dietary adaptation followed by 140 days of evaluation, divided into five 28-day experimental periods. Heifers were monitored for reproductive development by transrectal ultrasonography to detect corpus luteum (CL) formation. Evaluations began during the second experimental period and were conducted weekly, totaling 14 evaluations per animal throughout the study. The presence of a CL was used as an indicator of luteal activity, and heifers were considered pubertal on the day the structure was first detected. Growth performance was also monitored during the experimental period. Data were analyzed using the MIXED procedure of SAS, and treatment effects were considered significant at P ≤ 0.05. No treatment effects were observed for age at puberty (P = 0.75), body weight at puberty (P = 0.87), average daily gain until puberty (P = 0.73), or corpus luteum diameter (P = 0.19). At the end of the experimental period, all heifers in the control treatment reached puberty, whereas approximately 80% of heifers receiving ionophores (MON, NARA, and N+M) presented a corpus luteum. These results indicate that ionophore supplementation during feedlot development did not accelerate puberty in F1 Angus × Nellore heifers. However, the feedlot system allowed early identification of heifers that reached puberty, which may support management decisions for replacement selection. Heifers that fail to reach puberty during this period may be redirected to finishing systems, whereas pubertal females may be retained as replacements, improving efficiency in beef production systems.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"40 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PS4-2. Triticale Silage Used as Ruminal in Situ Substrate to Assess the Effects of Saccharomyces Cerevisiae in Beef Cattle Grower and Finisher Diets.","authors":"Fernanda Berumen, Jhones O Sarturi, Ahmari D Henry, Brooke A McCrumb, Kaliu Scaranto Silva, Kip K Karges, Beatriz Q Dos Reis, Osman R A Melgar, Otavio France","doi":"10.1093/jas/skag272.413","DOIUrl":"https://doi.org/10.1093/jas/skag272.413","url":null,"abstract":"Ruminal degradability kinetics of triticale silage (in situ substrate) of beef steers consuming beef cattle grower and finisher diets with or without (live yeast) Saccharomyces cerevisiae were evaluated. Eight surgically prepared beef steers were used in a duplicated 4 × 4 Latin square design (four 38-day periods) following a 2 × 2 factorial arrangement of treatments: A) presence of live yeast (Saccharomyces cerevisiae [CNCM I-1077], at 1 × 1010 CFU/animal-daily); and B) diet type (steam-flaked corn-based grower or finisher diets [ad libitum intake]). Live yeast was delivered via gel capsules (0.25 g, as-is) twice daily through the ruminal cannula. Pre-dehydrated (55ºC for 72 h) triticale silage substrate was ground (2 mm) and placed into 10 × 20 cm (28 µm) nylon bags (5g, as-is). Bags were placed in the ruminal ventral sac within a nylon mesh (with weights) and reversely removed at 0, 2, 4, 8, 12, 20, 32, 48, 64, 72, and 96 h after incubation. Residue bags were rinsed and dehydrated for 72 h at 55ºC. Residue duplicates were composited, corrected for moisture, and used to fit a first-order kinetics model using the NLIN procedure of SAS. The GLIMMIX procedure of SAS was used with animals as the experimental unit, the fixed effects (diet, period, interaction), and the random effects of animal ID within square, square, and period. Live yeast inclusion tended (Diet × Yeast interaction, P = 0.06) to increase the rate of degradation and the effective degradability calculated at 4, 5, and 6 %/h of the substrate organic matter (OM) when offered in finisher diets, while not affecting such fractions in grower diets. Regardless of diet type, live yeast increased the substrate dry matter (DM) rate of degradation (P = 0.04), tended (P = 0.10) to increase the effective degradability of the DM fraction (calculated at 4%/h rate of passage), and tended (P = 0.11) to decrease the substrate hemicellulose fraction lag-time (h). Regardless of live yeast inclusion, steers offered the grower diet had greater (P < 0.01) triticale silage substrate potentially degradable fraction, lesser undegradable (P < 0.01), and greater (P < 0.01) effective degradability calculated at 4, 5, and 6 %/h rate of passage for DM, OM, NDF, ADF, and hemicellulose fractions, while also tending (P = 0.11) to increase the substrate DM rate of degradation compared to finisher diets. The current ruminal in situ model replicated expected results between beef cattle steam-flaked corn-based grower and finisher diets when using a forage substrate. Live yeast seemed to improve ruminal effective degradability of a high-quality forage substrate (triticale silage) OM fraction in a beef cattle finisher diet more intensively than in a grower diet, while other positive effects were observed regardless of diet type.","PeriodicalId":14895,"journal":{"name":"Journal of animal science","volume":"10 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149077904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}