Search Results (159)

Feed intake and diet quality are key factors influencing enteric methane (CH₄) emissions in ruminants. Low-quality C₄ grasses typically limit intake and are associated with high CH₄ yield. Nitrogen supplementation may improve rumen function and reduce CH₄ emissions per unit of feed intake, although responses under low-quality forage conditions remain insufficiently characterized. The goal of the study was to evaluate the effects of nitrogen supplementation (urea- or nitrate-containing supplements) on the utilization of low-quality weeping lovegrass hay (Eragrostis curvula) and CH₄ yield in beef steers. Twenty-four Aberdeen Angus steers (326 ± 27 kg body weight) were assigned to three treatments: (1) weeping lovegrass hay alone; (2) weeping lovegrass hay + sunflower expeller + urea; and (3) weeping lovegrass hay + sunflower expeller + potassium nitrate (KNO₃). The proportion of non-protein nitrogen (NPN; urea and KNO₃) included in the supplements was set according to the maximum tolerated threshold. Methane emissions were measured using the SF₆ tracer technique. Compared with the hay-only treatment, supplemented animals increased dry matter intake (DMI) by 35% and 38% in the urea and nitrate treatments, respectively (p < 0.01). Total CH₄ emissions (g/d) were not affected by treatment (p = 0.16). However, CH₄ yield (g CH₄/kg DMI) decreased by 27% and 38% in the urea and nitrate treatments, respectively (p < 0.01). The methane conversion factor (Ym) was also reduced in supplemented animals. Under the conditions of this study, supplementation of low-quality weeping lovegrass hay with nitrogen-containing supplements increased feed intake and reduced CH₄ yield without affecting total CH₄ emissions. These findings highlight the importance of considering CH₄ emission intensity, in addition to absolute emissions, when evaluating mitigation opportunities in forage-based beef production systems. Full article

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

Efficient grazing management is critical for optimising animal growth and carcass quality in dairy beef systems; however, the combined effects of turnout date to spring pasture and post-grazing sward height have not been well quantified. This study evaluated the effects of spring turnout date (early vs. late) and post-grazing sward height (3.5 vs. 5.5 cm) on steer performance, intake, and carcass attributes, over three production cycles in a dairy calf-to-beef system. A total of 188 dairy and dairy × beef steers (initial body weight approximately 250–285 kg) were used across three experiments, conducted in a pasture-based calf-to-beef system. Animals grazed for ~200 days followed by ~100 days of indoor finishing. Early turnout improved average daily gain during early- and mid-season (p < 0.05 to p < 0.001), but differences had disappeared by housing, with no effect on carcass traits (p > 0.05). Grazing swards to 5.5 cm increased average daily gain at pasture (p < 0.01) and housing weight in the three experiments (p < 0.01). Animals grazed to 3.5 cm at pasture subsequently had a higher indoor finishing average daily gain (p < 0.05). Grazing to a stubble height of 5.5 cm improved (p < 0.001) daily gain at pasture but reduced finishing daily gain (p < 0.001). Carcass weight per day of age and were unaffected by either factor (p > 0.05), and no significant turnout × post-grazing sward height interactions were detected for any measured variables (p > 0.05). These findings indicate that maintaining a higher post-grazing sward height provides improved animal performance, while early turnout offers short-term gains, supporting grazing strategies that prioritise sward height management for sustained performance. Full article

Dark cutting (DC) is a significant quality defect in beef, often linked to stress experienced by animals prior to slaughter. This study evaluated how antemortem handling affects behavior and DC incidence in Holstein (n = 101) and commercial crossbred (CC; n = 101) steers finished under the same commercial conditions in northwestern Mexico. Animal welfare and handling practices were assessed during driving, transport, lairage, stunning and bleeding, and carcass and meat traits related to DC were measured. Holsteins, originating from confined systems with high human–animal interaction, showed more backing events than CC (73 vs. 30; p = 0.03), which led operators to increase vocal encouragement (109 vs. 5; p < 0.001) and hitting (100 vs. 28; p = 0.002). Additionally, 56.4% of Holstein carcasses had L* ≤ 40 compared with 22.8% in CC (p = 0.001), whereas a greater proportion of CC carcasses exhibited ultimate pH ≥ 5.8 (46.5 vs. 20.8%; p = 0.03). Meat from Holstein steers showed lower lightness, lower redness and higher yellowness, together with a higher incidence of DC (17.8 vs. 10.9%). In conclusion, genetic background and the human–animal relationship influence responses to antemortem handling and the incidence of dark cutting. Full article

This study evaluated the effects of forage-free diets with reduced starch levels on the productive performance, metabolism, ruminal fermentation, nutrient digestibility, and meat quality of feedlot beef cattle. Two experiments were conducted. In Experiment 1, forty uncastrated Nellore steers were distributed into 20 pens in a completely randomized design, receiving diets with increasing inclusion levels of ground corn in the total diet: C400 (400 g kg⁻¹), C200 (200 g kg⁻¹), C100 (100 g kg⁻¹), and C50 (50 g kg⁻¹), formulated without forage and based on fibrous co-products. Increasing ground corn inclusion promoted linear improvements in final body weight and average daily gain, while dry matter intake and feed efficiency showed quadratic responses. Meat quality parameters were not affected by dietary treatments. In Experiment 2, eight crossbred steers were assigned to a double 4 × 4 Latin square design and fed the same experimental diets. Higher corn inclusion increased starch and fat intake, whereas dry matter, organic matter, and protein intake showed quadratic responses. Apparent total-tract digestibility of dry matter, organic matter, and starch also followed a quadratic pattern. Ruminal fermentation parameters were affected by dietary treatments, with greater ammoniacal nitrogen concentrations at higher corn levels and quadratic responses for propionate, butyrate, and methane production. Nitrogen metabolism indicated increased urinary nitrogen and uric acid excretion with increasing dietary corn inclusion. These results demonstrate that forage-free diets based on citrus pulp and soybean hulls with different levels of ground corn can be effectively used in finishing beef cattle, improving performance without impairing meat quality while modulating ruminal fermentation and nutrient utilization. Full article

While essential oils are gaining momentum as a strategy to modulate rumen function and potentially reduce enteric methane in cattle, little is known about how their bioactive components, terpenes, affect rumen microbes. Our objective was to evaluate how in vivo doses of thymol affect the structure and function of the rumen microbial community via whole genome shotgun sequencing (WGS). Four beef steers were used in a 4 × 4 Latin square with four 28 d periods. Steers consumed ad libitum forage and received one of four thymol doses (0 [CON], 120 [120-T], 240 [240-T], and 480 [480-T] mg/kg forage intake). Rumen contents were separated into liquid and solid fractions, DNA was extracted, analyzed via WGS, and assessed with orthogonal contrasts. After FDR correction, no taxa were affected by thymol; however, raw p-values demonstrated responses to thymol supplementation for solid-associated uncultured Lachnospiraceae bacterium (p = 0.04), uncultured Methanobrevibacter (p = 0.05), and uncultured Coriobacteriaceae bacterium (p = 0.02). Liquid-associated uncultured Prevotellaceae bacterium (p = 0.03), Prevotella sp. (p = 0.04), and Bacteroides sp. (p = 0.02) also responded to thymol, with the highest abundances observed at various thymol doses. Genes involved in energy production and amino acid metabolism transport were observed at the highest abundances at 240-T, while genes associated with cell cycle control, cell division, and chromosome partitioning were present in the highest abundances at 120-T. The findings suggest that thymol exerts dose-dependent effects on rumen microbial abundances and functional pathways, with 240 mg/kg forage intake appearing to be the most effective dose to downregulate methanogenic enzymes while also enhancing the enzymes associated with metabolism without negatively impacting microbial diversity. Full article

Background: Citrus components potentially suppress adipogenic differentiation and lipid accumulation, and exhibit anti-inflammatory and antioxidant effects. We hypothesized that the bioactive compounds in Citrus junos Sieb ex Tanaka (yuzu) fruit peel can alter the systemic metabolism and productivity of beef cattle. Methods: Japanese Brown (JBR) steers were fed with a diet supplemented with 2.5% yuzu peel during the last month of the finishing period. To investigate the effect of dietary yuzu supplementation (DYS) on beef and liver metabolism, we explored the metabolomic profiles of longissimus thoracis (LT, loin) muscle at 14 d postmortem using capillary electrophoresis (CE-TOF/MS) and high-performance liquid chromatography time-of-flight mass spectrometry (LC-TOF/MS). Results: The DYS treatment enhanced the beef fat score compared to that recorded in beef in the no-DYS (None) group (p = 0.050); however, the other carcass quality traits were not significantly different between the DYS and None groups. CE-TOF/MS and LC-TOF/MS revealed 242 and 107 annotated peaks, respectively, for the LT muscle. DYS significantly increased 9(S)-hydroxyoctadecadienoic acid (9-HODE, a beef flavor precursor), cyclo(-Leu-Pro), spermidine, asymmetric dimethylarginine, and 7α-hydroxycholesterol levels and reduced 2-ethylhydracrylic acid (2-EHAA), γ-tocopherol, coenzyme Q10 (CoQ10), sphingomyelin(d18:1/16:0), Cys-Gly, Tyr-Arg, and palmitoylcarnitine levels in postmortem LT muscle (p < 0.050). Concomitantly, in the fresh liver, DYS increased acetyl-CoA, 6-phosphogluconic acid, S-methylglutathione, ATP, ribulose 5-phosphate, and ADP levels and suppressed the content of thiamine, Ala-Ala, riboflavin, and ascorbate 2-sulfate (p < 0.050). Conclusion: Collectively, yuzu ingredients activated ATP production in the liver through the elevation of hepatic energy metabolism primarily in the citrate cycle and β-oxidation, and potentially altered muscle metabolism, including linoleic acid oxidation, FAD-mediated electron transport chain, and isoleucine catabolism, as demonstrated in the reduced accumulation of 2-EHAA and CoQ10 in DYS beef. Moreover, DYS likely affects the gut microbiome by enhancing the production of cyclo(-Leu-Pro), an antimicrobial dipeptide. Full article

Early diagnosis of heat load in beef cattle remains a challenge due to the limited understanding of behaviour-based indicators. This preliminary longitudinal study aimed to validate behavioural and physiological responses previously identified as heat load indicators. Black Angus steers were exposed to high environmental temperatures expected to cause heat load in the following sequence: an initial thermoneutral period, a hot period, and a recovery period. Changes in the positioning of key body parts, feeding behaviour, body maintenance, respiratory dynamics, and eye temperature were monitored. In the hot period, cattle increased their respiration rate, panting, and infrared eye temperature. Increased stepping by their left limbs suggested involvement of the right brain hemisphere in a stress response to high environmental temperatures. Cattle also held their heads more downward, ears backward, and their tail vertical, and reduced eating, grooming, and scratching during the hot period. Cattle responses to hot conditions were persistent in the recovery period, reflecting diagnostic relevance of the head, ear, and tail movements, stepping, especially by left limbs, and infrared eye temperature as non-invasive tools to identify heat load condition in cattle. The study reinforces our understanding of the specific behavioural and physiological responses to heat load condition, especially those involving left-limb stepping, ear and tail posture, and infrared eye temperature, are reliable indicators for identifying cattle experiencing high environmental temperature. Full article

Integrated crop grazing systems can improve farm profitability due to enterprise complementarity. Utilizing the supply of N from legumes, livestock manure, and plant residues will result in improving grain yield and quality. A long-term 12-year integrated systems study evaluated continuous spring wheat (HRSW-CTRL) with spring wheat (HRSW-ROT) grown in a five-crop rotation: (1) spring wheat, (2) seven-species cover crop, (3) forage corn, (4) field pea/forage barley mix, and (5) sunflower. Yearling beef cattle steers grazed the field pea/forage barley mix, unharvested corn, and a seven-species cover crop. Spring wheat was marketed as a cash crop. Contrary to expectations, HRSW-ROT did not significantly increase grain yield or improve quality over HRSW-CTRL. Improved soil fertility was observed in the HRSW-ROT plots throughout the study relative to SOM, N, P, and K. However, the rotation with grazing management significantly reduced input costs but resulted in negligible gross and net returns over the 12-year period. Year-to-year weather variability was the cause of the differences between the two production management methods. Full article

Thymol is an antimicrobial terpene with potential as a feed additive for cattle; however, in vivo data describing the response of forage-fed beef cattle to the increasing provision of thymol is limited. As thymol may affect palatability and exert antimicrobial effects on rumen microbes, defining its effects in vivo is critical to inform adoption. Accordingly, the objectives of this study were to evaluate cattle acceptance of thymol and characterize the effects of increasing thymol doses on diet utilization and ruminal fermentation, with the overarching goal of identifying a maximum tolerable dose for beef cattle. Two 4 × 4 Latin Square experiments were conducted using beef steers consuming forage and providing thymol dosed on alfalfa. Experiment 1 assessed acceptance of thymol at increasing concentrations (0, 110, 220, and 330 mg/kg intake), and experiment 2 assessed diet utilization and fermentation in response to one of four thymol doses: 0, 120, 240, and 480 mg/kg intake. For experiment 1, thymol dose did not affect treatment or forage intake (p ≥ 0.17). For experiment 2, thymol did not linearly or quadratically affect (p ≥ 0.28) forage organic matter (OM) intake or OM digestibility. There were also no linear or quadratic effects (p ≥ 0.09) on ruminal ammonia-N, volatile fatty acids, or pH. These data indicate that thymol can be provided to beef cattle at up to 330 mg/kg intake and 480 mg/kg intake without negatively impacting acceptance and diet utilization, respectively. Full article

Beef production in intensive systems requires optimal nutrition to maximize growth and profitability. While triglycerides contain twice the energy per unit weight compared to polysaccharides, they are not nearly as commonly used as a supplemental source of energy compared to starch, largely in part due to their negative effects on rumen physiology when their inclusion levels are too high. To gain further insights into the response of rumen microbial communities to elevated dietary lipid levels, we took advantage of rumen samples collected as part of a previously published study that tested high inclusion (4% and 8%) of tallow or linseed oil in beef cattle as part of a 5 × 5 Latin square design, with corn used as a base dietary ingredient. Using a 16S rRNA gene-based profiling approach, two uncharacterized candidate rumen bacterial Operational Taxonomic Units (OTUs), referred to as Bt-995 and Bt-1367, were found to be in higher abundance in rumen samples collected from steers when they were fed diets with higher inclusion of linseed oil. Using a metagenomics approach to assemble contigs corresponding to genomic regions of these OTUs, various predicted metabolic functions were found to be shared. Consistent with the dietary treatments of the original animal study, functions associated with starch utilization and triglyceride metabolism were identified. Unexpectedly, however, contig sets from both OTUs also encoded genes predicted to be involved in vitamin B₁₂ biosynthesis, as well as ethanolamine utilization, a function that is dependent on vitamin B₁₂ as a co-factor. Together, these results indicate that vitamin B₁₂-related functions may provide an advantage to rumen bacteria under conditions of high dietary triglyceride inclusion. Full article

Understanding the genetic regulatory mechanisms of fat accumulation is crucial for improving beef quality. Hanwoo (Korean native cattle) is renowned for its high intramuscular fat (marbling), yet the genetic regulation of adipose gene expression remains insufficiently understood. In this study, we performed expression quantitative trait loci (eQTL) analysis using RNA-Seq data and genotype data from backfat tissue of 75 Hanwoo steers to identify regulatory variants associated with adipose deposition. A total of 25,042 significant cis-eQTL associations (FDR < 0.05) were identified, and 5362 unique top cis-eQTL pairs were retained after gene-wise filtering. Key cis-regulated genes included AGBL1, CACNG1, MYO18B, and DUSP29, which are involved in cytoskeletal organization, muscle development and calcium signaling. Three major cis-regulatory hotspots were located on BTA15 (BTA15:50354741) and BTA21 (BTA21:21526143, and BTA21:21541921). Permutation-based analysis (100,000 iterations) was conducted to control false positives, identifying 12 statistically significant trans-eQTL hotspots (FDR q < 0.05), of which SNP 6:60512276 and SNP 21:17035557 exhibited extensive trans-regulatory activity influencing 429 and 161 genes, respectively. In particular, SNP 21:17035557 acted as a shared cis- and trans-regulatory hub, indicating hierarchical control of adipose gene networks. Functional enrichment analyses revealed significant involvement of cytoskeleton- and calcium-dependent pathways, highlighting the interplay between structural remodeling and metabolic regulation in adipose tissue. These findings provide a comprehensive, system-level view of adipose gene regulation in Hanwoo cattle and highlight candidate molecular targets for genome-assisted and precision breeding. Moreover, this study offers quantitative genomic resources that can support the development of prediction models and decision-support systems for improving carcass traits in Hanwoo breeding programs. Full article

Warm-season grasses are the main source of feed in tropical and subtropical beef cattle production systems. The objective was to assess cattle preference among three warm-season grasses and explore its relationship with forage yield and plant structural traits. The three species were cultivated in 2 × 2 m plots using a completely randomized design. Cattle preference was evaluated in spring (December 2016 and 2017), summer (March 2017), and autumn (May 2017) using six Braford steers that grazed the plots for 4 h on two consecutive days. Pre-grazing forage yield, plant height, leaf-blade length, leaf-blade width, and the proportions of five leaf tissues at three leaf regions were measured at each date. Cattle preference was variable among the three species and evaluation dates. Paspalum atratum exhibited the highest pre-grazing forage yield, and constituted the tallest plants with the longest leaves during the summer. Urochloa brizantha showed the greatest proportion of vascular bundle sheath (17–30% at the midrib region, 25–31% at the interveinal region and 14–23% at the margin region) and P. atratum exhibited the greatest number of primary vascular bundle. Cattle preference was negatively correlated with the number of primary vascular bundle, pre-grazing forage yield, plant height and leaf-blade length. Full article

One hundred thirty-three high-risk crossbred beef steers and bulls (178.2 ± 20.9 kg) were used to evaluate dietary inclusion of a tannin (BXA) blend pellet during a 63 d receiving period and a 126 d grazing period compared with no dietary treatment (CON). Data were analyzed using SAS 9.4 with pen as the experimental unit. During receiving, no differences were noted on average daily gain (ADG) on a deads-out (p > 0.25) or deads-in (p > 0.75) basis. There were tendencies for increased DMI associated with BXA from D0–21, D23–42, and D0–42 (p < 0.13). During the grazing period, cattle fed BXA had greater ADG from D0–56, and D0–84 (p ≤ 0.05), and tended to have greater ADG from D0–28, D0–112, and D0–126 (p ≤ 0.09). Total period ADG (deads-out) did not differ between treatments (p = 0.18) nor on a deads-in basis (p = 0.20). No differences were noted in the percentage of animals treated for bovine respiratory disease (p = 0.19), death loss (p = 0.62), or percentage of animals removed as chronically morbid/dead (p = 0.90). Results indicate that BXA did not improve performance or health during the receiving period. However, this additive had positive effects during the grazing period. Full article