Search Results (293)

The objective of this trial was to evaluate the impact of an α-tocopherol injection on pre-weaning calf performance including markers of growth and behavior. Sixty-one days prior to weaning, both nursing Angus and Hereford steer calves (SC; n = 16) and Angus and Hereford heifer calves (HC; n = 28) were randomly assigned to one of two treatments: (1) no injectable α-tocopherol (CON; n = 23) or (2) 1500 IU of injectable α-tocopherol administered subcutaneously (VitE; n = 21). Average daily gain (ADG), exit velocity (EV), serum urea nitrogen, serum cortisol, and serum α-tocopherol concentrations were evaluated on d 0, 28, and 61 of the trial. Steer calves increased (p = 0.01) ADG compared to HC, with SC gaining about 13% more than HC. There was no impact (p ≥ 0.20) of injectable vitamin E on calf ADG. As the trial progressed, EV slowed (p = 0.0005) in both HC and SC regardless of treatment. Serum α-tocopherol concentrations were influenced (p = 0.04) by an interaction of treatment, sex, and time, with CON-SC being the only group that did not have serum α-tocopherol concentrations decrease throughout the trial. Overall, this trial found that a pre-weaning vitamin E injectable did not improve pre-weaning calf performance, but calf sex did. Full article

The objective of this study was to evaluate the impacts of varying inclusion levels of soybean hull pellets (SHP) with annual ryegrass baleage (BAL) on animal performance and digestive kinetics in beef cattle. In Experiment 1 (Exp. 1), 60 weaned mixed-sex beef calves were randomly assigned to one of three treatments: 0.0%, 0.5%, or 1.0% body weight (BW) SHP with ad libitum access to BAL for 48 days (d). Animal performance, including BW, dry matter intake (DMI), and average daily gain (ADG), was evaluated for the duration of the study. In Experiment 2 (Exp. 2), six ruminally cannulated beef steers received the same treatments utilized in Exp. 1. Steers were dosed with ytterbium (Yb)-labeled BAL to evaluate ruminal passage rate across three 24 d periods. All data were analyzed using SAS 9.4. In Exp. 1, total BAL intake decreased in calves supplemented with SHP, while cumulative ADG increased from 0.30 (0.0% BW SHP) to 0.54 (0.5% BW SHP) and 0.74 kg/d (1.0% BW SHP), respectively. Final BW at D47 also increased as SHP inclusion increased. In Exp. 2, ruminal retention time decreased from 38.0 h (0.0% BW SHP) to 15.1 h (1.0% BW SHP), while cecum-to-proximal colon passage rate did not differ among treatments (p = 0.06). Baleage DMI did not differ between treatments. Results suggest that SHP supplementation improved calf performance despite reduced BAL intake in Exp. 1, with the greatest cumulative ADG observed in calves supplemented with 1.0% BW SHP. In Exp. 2, 1.0% BW SHP produced the greatest effects on passage rate kinetics, while BAL DMI was unaffected by SHP supplementation. Full article

This study investigated the associations among dam lactation number, passive immunity transfer, internal parasite burden, and weaning performance in female calves. Early consumption of high-quality colostrum is critical for effective passive immunity transfer, calf health, and long-term productivity. Colostrum composition may vary with management practices and dam lactation number, potentially influencing immunity and disease susceptibility. Forty-five cows and their female offspring (n = 45) were allocated to three groups by lactation number: first lactation (LAC1), second lactation (LAC2), and third lactation (LAC3) (15 cows and 15 calves per group). Calf birth weight was recorded. Colostrum immunoglobulin G (IgG) concentration was measured using a colostrometer and refractometer, and chemical composition (fat, protein, and non-fat solids) was analyzed. Fecal samples collected at 30, 60, and 90 days of age were examined for Eimeria spp. Colostrum IgG concentration, °Brix percentage, specific gravity, and non-fat solids did not differ among lactation groups (p > 0.05). LAC3 cows had higher colostrum protein content, while LAC1 cows had greater fat concentration (p < 0.05). Calves from LAC1 dams were lighter at birth than those from LAC2 and LAC3 dams (p < 0.001). The prevalence of Eimeria spp. was not influenced by lactation number, birth weight, or colostrum quality (p > 0.05), but treatment costs were higher in calves from LAC3 dams (p < 0.01). In conclusion, lactation number affected colostrum composition and calf growth but did not alter IgG concentration, underscoring the importance of effective colostrum management to improve calf performance and dairy system sustainability. Full article

This study evaluated the effects of maternal overfeeding during mid-to-late gestation on maternal productivity, metabolic status, reproductive recovery, and calf performance in Hanwoo cattle using conventional statistics and machine learning (ML) approaches. A total of 243 pregnant cows were assigned to either a control group or an overfeeding group from gestation day 90 to parturition. The overfeeding treatment increased nutrient supply to approximately 140–145% of the control level. Maternal body weight (BW), body condition score (BCS), serum metabolites, and reproductive traits were evaluated throughout gestation and postpartum, while calf growth, morphometrics, and metabolic traits were assessed at birth and weaning. Calves were further classified into growth- or meat-quality-oriented genotypes using SNP-based profiling. Overfeeding increased maternal BW gain and BCS during gestation and reduced circulating non-esterified fatty acid concentrations, indicating improved maternal energy status. However, overfed cows showed a longer interval to postpartum estrus return. Calf birth weight was not significantly affected by maternal overfeeding, whereas calf growth and morphometric traits at weaning were more strongly influenced by parity, sex, and genotype. Machine learning models identified gestational BW, metabolic indicators, calf feed intake, and genotype as major predictors of maternal and calf outcomes, with random forest and XGBoost showing superior predictive performance compared with linear models. These findings suggest that parity- and genotype-informed nutritional management combined with ML-based prediction may support precision feeding strategies in beef cattle production systems. Full article

Research on free-ranging animal species, which extends from the breadth of stock identification and population dynamics to fine-scaled analysis of behavior, depends on identifying individuals. Recognizing wild bottlenose dolphins (Tursiops truncatus) primarily depends on photographs of distinct patterns of notches which eventually develop on the trailing edge of most dorsal fins. Although photo-identification has advanced to include computer-aided fin identification software, there can still be error related to dolphins whose identifying patterns are subtle, obscured, or absent (“clean fins”). Facial pigment patterns on dolphin species were described as bridle marks over a hundred years ago. The purpose of this descriptive study was to evaluate bridle mark presence, distinctiveness, and permanence as a supplement to dorsal fin photo-identification. A 17-year population census of 860 bottlenose dolphins in Palm Beach, Florida, USA, includes 458 dolphins with photographic records showing bridle marks. A subset of 30 dolphins, based on an encounter history spanning at least 7 years, was coded using a 17-point system. The results confirmed bottlenose dolphin bridle mark distinctiveness and permanence on all 30 dolphins. In conclusion, bridle marks can supplement photo-identification as a double-mark system to improve accuracy. This tool is helpful for recognizing calves with clean dorsal fins post weaning and adults without dorsal fin markings. Full article

The escalating global threat of antimicrobial resistance (AMR) has intensified efforts to identify safe, effective, and sustainable alternatives to in-feed antibiotics in livestock production. The bovine gastrointestinal microbiome plays a central role in host immunity, nutrient utilization, and disease resilience, positioning microbiome-modulating interventions as promising candidates for antimicrobial stewardship. Despite growing experimental interest, a systematic synthesis of the available evidence in cattle is lacking. This systematic review aimed to evaluate the efficacy of microbiome-modulating interventions, including probiotics, prebiotics, postbiotics, phytogenic feed additives, essential oils, organic acids, and native rumen microbial supplements, as strategies to reduce antimicrobial use in cattle, and to characterize their effects on gut microbial diversity, fermentation characteristics, and host health and performance outcomes. A systematic search of Scopus, Web of Science, and EBSCOhost (including Academic Search Ultimate, MEDLINE with full text, and CAB Abstracts with Full text) was conducted in accordance with PRISMA guidelines. Studies were eligible if they used cattle (dairy cattle, beef cattle, calves, or mixed production systems), employed a microbiome-modulating intervention, and reported at least one microbiological or host outcome. Seventeen peer-reviewed studies published between 2010 and 2025 were included after full-text screening. Risk of bias was assessed using an adapted SYRCLE tool, which identified moderate overall study quality; the majority of included studies were randomized controlled trials or controlled experiments, though reporting of allocation concealment and blinding was inconsistent across studies. Across the 17 included studies, five broad categories of interventions were evaluated: probiotics (n = 5 studies), prebiotics (n = 2), postbiotics and organic acids (n = 4), phytogenic additives and essential oils (n = 4), and native rumen microbial supplements (n = 2). Animals spanned neonatal dairy calves, weaned Holstein calves, dairy heifers, lactating dairy cows, and Bos indicus feedlot beef cattle. Probiotics and organic acids most consistently improved growth performance: benzoic acid supplementation increased average daily gain by 8.4% (p < 0.05) and fructo-oligosaccharide prebiotics elevated body weight at weaning by 6.7% (p < 0.01). Native rumen microbial supplements improved energy-corrected milk yield by up to 3.1% without increasing dry matter intake. Polyphenols and bile acids demonstrated the strongest immunological and disease-preventive effects, reducing calf mortality by approximately 40% and disease severity by approximately 35%, respectively. Microbiome analyses revealed intervention-dependent increases in microbial diversity and shifts toward taxa associated with improved fermentation efficiency, including enrichment of propionate-producing Prevotellaceae, butyrate-associated Ruminococcus, and hindgut Bifidobacterium. Rumen fermentation outcomes included reductions in the acetate:propionate ratio and ammonia-N concentrations and improvements in fiber digestibility of 3.6–4.4 percentage units in dairy cows. Phytogenic additives preserved microbial diversity without inducing broad-spectrum suppression, functioning primarily as microbiome stabilizers rather than direct antimicrobial replacements. This systematic review provides evidence that gut microbiome modulation may enhance growth performance, improve fermentation efficiency, and reduce disease susceptibility in cattle, thereby supporting antimicrobial use reduction across dairy, beef, and mixed production systems. Effect magnitudes varied substantially across intervention categories and production contexts, and study quality was moderate, underscoring the need for larger, pre-registered trials with standardized outcome reporting and direct antibiotic comparator arms. Probiotics, prebiotics, and bile acid metabolites showed the greatest potential as components of integrated antimicrobial stewardship strategies in cattle production. Full article

The physiological impact of climatic stress is well documented in ruminants, but the acute stress resulting from personnel rotation and its health and welfare consequences are poorly understood. The objective of this observational prospective longitudinal study was to assess the endocrine, inflammatory, behavioral, and cardiorespiratory responses of pre-weaned Zebu-cross calves (¾ Zebu x ¼ Holstein) to handler substitution and environmental variables in the Mexican humid tropics during the rainy season. Fourteen calves were monitored over a 68-day period. The initial behavioral (n = 14) and physiological (n = 5) assessments (S1) were conducted after a 30-day stabilization period with the familiar handler to ensure that animals had reached a physiological steady state, free from the influence of previous personnel rotations and from familiarization with two external observers, prior to the first assessment. Subsequently, the handler was replaced for 17 days (S2). The third (S3) and fourth (S4) samplings were conducted after the familiar handler was reinstated (21-day). There was a significant increase in plasma cortisol and abnormal suckling behaviors at S2 compared to S1 and S4, and a C-reactive protein increase in S3. Furthermore, strong correlations were found between calf handler and cortisol, heart rate, respiratory rate, latency to suckle, and cross-sucking, suggesting an acute stress response with a delayed inflammatory response secondary to the handler’s substitution. Environmentally, ambient temperature (AT, °C) showed no correlation with cortisol levels, indicating that the primary driver of the neuroendocrine and behavioral changes was handler substitution rather than climatic variations. Full article

Dairy production in Indonesia relies on two contrasting calf-rearing systems: concentrate-driven commercial dairy systems (CDS) and smallholder farms (SH). As these systems differ in feeding practices, they may influence gut development in calves. This study examined how farm management affects the fecal microbiota and metabolites in healthy and diarrhea post-weaning calves. Fecal samples were collected from 11 and 14 calves from CDS and SH facilities, respectively. Gut bacterial communities were analyzed using 16S rRNA gene amplicon sequencing, and metabolites were characterized using untargeted gas chromatography–mass spectrometry (GC-MS). Microbial diversity, metabolite profiles, and correlation networks were compared between the farm types and diarrhea status. Our results showed that farm management strongly shaped microbial community structure and metabolic outputs, but did not alter microbial richness. Although diarrhea is typically associated with reduced microbial richness, it did not affect the microbial community structure, suggesting that it primarily impacted microbial function, particularly the metabolic environment. Correlation network analysis revealed stronger linkages between microbes and metabolites in SH calves, especially under healthy conditions. Overall, these findings indicate that dietary structure is a key determinant of fermentation stability, with CDS calves showing greater metabolic instability. In contrast, SH calves maintain a more resilient, fiber-driven functional state. Full article

The aim of this study was to perform a systematic review of studies published in the last 25 years to determine the influence of calving management (type of calving pen, bedding, frequency of cleaning), birth monitoring, birth induction, and dystocia on calf morbidity and mortality. The following databases were used for research: PubMed, CAB Abstracts, and Web of Science. In total, four studies were included for birth induction, sixteen for calving management, eight for birth monitoring, and twenty for dystocia. All factors included had an influence on perinatal mortality. Calving management and dystocia influenced mortality up to weaning. Severe cases of dystocia raised the risk of mortality from 11.2 to 53.17 and even cases of moderate dystocia led to an increased risk of mortality from 2.04 to 11.6. Passive transfer of immunity was improved by more frequent birth monitoring. Dystocia increased the risk of failure of passive transfer. Good calving management and performing of birth monitoring reduced the risk of morbidity. Dystocia led to a higher risk of morbidity. Dystocia had the greatest influence on the parameters examined. This systematic review provides evidence that intrapartum factors have an influence on calf morbidity and mortality and shows possibilities to improve calf health outcomes. Full article

Winter feeding represents a significant cost in beef production, requiring efficient strategies that maintain productivity while minimizing environmental impact. Forty-six pregnant cows (620 ± 61 kg BW) were used to evaluate an ad libitum hay-based diet (2.02 Mcal/kg ME; HFOR; n = 23) versus a corn-based diet (2.84 Mcal/kg ME) limit-fed at 1.2% BW (HCON; n = 23) from 50 d pre-calving to 84 d post-calving. Pre- and post-calving, HCON cows consumed less (p < 0.01) dry matter, crude protein, and water than HFOR cows. While CH₄ yield per kg DMI was greater (p < 0.01) for HCON cows, total daily CH₄ emissions and CH₄ per unit of NEm intake were lower (p ≤ 0.03) compared with HFOR cows. Behavioral data showed that HCON cows had fewer (p < 0.01) meals and spent less time eating, but had greater intake per minute. Cow BW differed by treatment over time (p < 0.01), with HCON cows weighing less through early lactation, though no differences were observed from d 84 to weaning. Calf BW remained unaffected (p ≥ 0.76). In conclusion, limit-feeding a corn-based diet improves feed and water use efficiency and reduces enteric CH₄ emissions without compromising calf growth, offering a viable alternative to traditional forage-based wintering systems. Full article

The objective of this study was to evaluate the effects of timing of injectable trace mineral (ITM) administration (28 days (d) prior to or at weaning) on performance and health in mixed-sex beef calves (n = 115; 224 ± 40 kg). Calves were randomly assigned to one of the following treatments: (1) no ITM (CON), (2) ITM administered 28 d before weaning (PW), or (3) ITM administration at weaning (WEAN). At weaning, calves were transported to a local auction barn, held overnight, and returned the following day; BW, blood, and hair samples were collected prior to and through the receiving period. Data were analyzed using SAS 9.4. Serum Se increased in PW calves following ITM administration (p < 0.01). Serum Mn increased in PW and WEAN groups (p < 0.01) and PW calves showed increased serum Cu at weaning (p < 0.01). Across treatments, calves experienced 6% shrink following weaning and transport, with recovery of BW and intake occurring within 21 d and 8 d, respectively. Despite improved mineral status, no performance benefits were observed during the receiving period, reflecting adequate baseline mineral status and low-stress management conditions, suggesting that ITMs may have limited benefits in well-managed herds. Full article

Based on previous findings that fiber digestibility and rumen fermentation in weaned buffalo calves were improved by a roughage combination of dried sugarcane leaves (SDL) and peanut vine (PV), this study reveals that the mechanism for improving fiber digestibility and growth performance involves increasing Succiniclasticum abundance and 3-methoxytyramine-betaxanthin level, which consequently increases ruminal acetate and propionate. Twenty-one calves were fed pelleted diets with roughage combinations the 15% SDL combined with PV (S15PV, 15% SDL + 15% PV), the 22.5% SDL combined with PV (S22.5PV, 22.5% SDL + 7.5% PV), or the 30% SDL combined with PV (S30PV, 30% SDL) for 63 days. The results showed no significant differences in α-diversity and β-diversity among the three groups (p > 0.05). A significantly higher relative abundance of Succiniclasticum was observed in the S22.5PV group than in the other two groups, by 241.57% and 136.25%, respectively (p < 0.05), and its effects were primarily exerted through carbohydrate and amino acid metabolism pathways. Differential metabolites were mainly enriched in cofactor/vitamin metabolism (vitamin B6, riboflavin) and amino acid pathways (arginine, tryptophan). By PLS-DA analysis, significantly higher levels of Bentyl and 3-Methoxytyramine-betaxanthin were observed in the S22.5PV group compared to the S15PV and S30PV groups, respectively. Positive correlations were observed between Succiniclasticum and NDFD, ADFD, acetic acid, propionic acid, isovaleric acid, as well as 3-Methoxytyramine-betaxanthin (p < 0.05). In conclusion, the rumen microbial diversity was not altered by the roughage combinations of dried sugarcane leaves and peanut vine, but the abundance of Succiniclasticum and the level of 3-Methoxytyramine-betaxanthin were significantly correlated with NDFD and ADFD, which enriched ruminal AA and PA, and may thus be associated with improved growth performance. Full article

A study was conducted to evaluate the effect of neutral detergent fiber (NDF) levels of calf starter and weaning time on growth, rumen fermentation characteristics, serum metabolites, and rumen microbial diversity of Holstein calves. A total of 24 newly born male Holstein calves were randomly distributed to four groups in a completely randomized design with a 2 × 2 factorial arrangement of NDF levels (14% and 24%) and weaning time (d 44 and d 54). There was no interaction between starter NDF levels and weaning time for any trait except rumen acetic acid in the immediate post-weaning phase (p = 0.013). Starter NDF levels had no effect on growth, feed intake, and hay intake. Late-weaned calves had greater (p = 0.050) weight gain in the pre-weaning phase whereas, early-weaned calves showed greater weight gain (p = 0.004) and starter intake (p = 0.004) in the post-weaning phase although overall weight gain, and starter and hay intakes were not affected by weaning time. Rumen pH, ammonia nitrogen, and most volatile fatty acids remained unaffected by starter NDF levels and weaning except isobutyric acid which was greater in calves fed 24% NDF starter (p = 0.001) in the immediate post-weaning and isovaleric acid which was greater in early-weaned calves (p = 0.044) at the end of experiment. Serum metabolites were largely affected (p < 0.05) by starter NDF levels and weaning time in the pre-weaning phase only. Alpha diversity of rumen microbes was greater and chaotic in 14% NDF starter group (early- and late-weaned) in the pre-weaning phase which converged in the immediate post-weaning phase and diverged on starter NDF basis at the end of experiment. Microbial ecology at phylum and genus levels composition were greatly driven by starter NDF levels in the pre-weaning phase, by weaning time in the immediate post-weaning phase, and two distinct bifurcated microbial ecologies based on starter NDF levels appeared at the end of experiment. In conclusion, the comparable growth with distinct microbial diversity but largely in favor of 24% NDF starter suggests that calves can be subjected to early weaning with 24% starter NDF levels for smooth transition from liquid to solid feed in Holstein calves. Full article

This study evaluated the effects of an Astragalus membranaceus stem and leaf–Angelica sinensis stem and leaf mixture (AASL) as a medicinal feed supplement on immune function, antioxidant status, inflammatory responses, gut microbiota and the serum metabolome in weaned Simmental bull calves. Calves were fed diets containing different levels of AASL, and serum immunoglobulins, inflammatory cytokines, and antioxidant indices were determined. In addition, fecal short-chain fatty acid (SCFA) concentrations, gut microbiota composition, and serum metabolic profiles were analyzed, followed by correlation analyses among the microbiota, SCFAs and metabolites. The results showed that AASL was rich in crude protein, crude fat and trace elements. 4% AASL supplementation increased serum immunoglobulin (IgG and IgM) levels, decreased tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-1 beta (IL-1β) levels, and enhanced superoxide dismutase (SOD), glutathione (GSH) and total antioxidant capacity (T-AOC) activities (p < 0.01 or p < 0.001), indicating improved immune and antioxidant status and attenuated inflammatory responses. AASL also enriched beneficial bacterial genera, suppressed potentially harmful taxa, and increased SCFA concentrations. Differential metabolites were mainly enriched in tryptophan metabolism, lipid metabolism, neuroactive ligand-receptor interaction, sphingolipid signaling, and ATP-binding cassette (ABC) transporter pathways. Integrated microbiota metabolite analysis further suggested that AASL improved host metabolic status through the coordinated regulation of gut microbiota, SCFAs production and related metabolic pathways. Overall, AASL shows promise as a functional feed supplement for improving calf health. Full article