30 Nellore animals with an average weight of 407.25 ± 2.04 kg, were distributed in a completely randomized design across the following treatments: 1—Control (without inclusion of 3-NOP); 2—BV75 (inclusion of 3-NOP at 75 mg/kg DM); 3—BV100 (inclusion of 3-NOP at 100 mg/kg DM). No significant effects were observed between treatments on ingestive behavior. However, the notable effect on the BWfinal and ADG of animals supplemented with 3-NOP compared to the control group was measurable. Cattle beef receiving 3-NOP exhibited reduced methane emissions (p < 0.0001) for all variables analyzed, resulting in an average decrease of 38.2% in methane emissions compared to the control, along with increased hydrogen emissions (g/day) (p < 0.0001). While supplementation with BV100 demonstrated lower methane emission, the performance was lower than BV75 in DMI, BWfinal, ADG, and ADG carcasses. Partial separation of metabolomics observed between groups indicated changes in meat metabolism when comparing the control group with the 3-NOP group, identifying metabolites with a variable importance projection (VIP) score > 1. In conclusion, supplementation with 3-NOP effectively reduced methane emissions and did not negatively influence animal performance.

This study aimed to evaluate total mixed ration silages with sugarcane and the additives microbial inoculant and chitosan. Thirty mini-silos were used in a completely randomized design, with three treatments and ten replications. Silages were composed of sugarcane mixed with corn bran, whole soybean, urea, and mineral mixtures at a 50:50 roughage to concentrate ratio. Treatments consisted of control silage, microbial additive (Lactobacillus plantarum + Pediococcus acidilactici, 4 g/t of KeraSil, Kera Nutrição Animal), and chitosan (10 g/kg of natural matter). Silages were evaluated for fermentation and microbiological profile, fermentation losses, aerobic stability, chemical-bromatological composition, intake, and digestibility. Fermentation profile showed no significant difference between treatments for pH values, with a mean value of 4.79. Production of acetic and propionic acids showed no difference between treatments, with mean values of 7.34 and 0.053 mmol/kg DM, respectively. Dry matter, organic matter, and crude protein intake of the total mixed ration silage differed statistically from the other treatments (P0.05). Digestibility values of DM, OM, and NDF were higher in the total mixed ration silage (P0.05). Total mixed ration silage increased nutrient intake and digestibility, with a better fermentation pattern when added with the microbial inoculant.

Enteric methane (CH₄) mitigation strategies should reduce environmental impact without compromising animal productivity. Residual methane emission (RME) has been proposed as a phenotype for identifying cattle that emit more or less methane than predicted after accounting for relevant sources of variation, but its associations with host metabolism, carcass, and integrated sustainability remain poorly characterized. This retrospective study evaluated whether Nellore steers classified according to RME differed in ruminal fermentation, serum and meat metabolomic profiles, productive performance, economic indicators, and environmental efficiency. Twenty-nine steers were classified as low (n = 10), intermediate (n = 9), or high (n = 10) residual methane emitters based on RME calculated after adjustment for the original dietary treatment, mean daily dry matter intake, and metabolic body weight. Methane emissions were measured using the GreenFeed system, while ruminal fermentation, serum and meat metabolomes (H-NMR), productive performance, carcass traits, economic indicators, carbon credit scenarios, and integrated sustainability indices were evaluated. Low-RME animals emitted 23.6% less methane than high-RME animals (p < 0.001), while showing average daily gain, carcass gain, and final carcass weight comparable to those of high-RME animals (p > 0.05). Differences in ruminal fermentation were also observed among phenotypes, with low-RME animals showing a greater propionate-to-acetate ratio and intermediate-RME animals showing greater acetate concentration and acetate-to-propionate ratio (p < 0.05). Exploratory principal component analysis revealed partial separation of serum metabolomic profiles but no overall discrimination of meat metabolomes. In contrast, sparse partial least squares analysis identified an exploratory multimetabolite pattern associated with RME, with serum glutamine, creatinine, carnitine, serine, citrate, and meat succinate among the metabolites contributing most strongly to the observed differentiation among methane emission phenotypes. Low emitters also achieved the greatest carcass margin, carbon credit revenue, eco-efficiency, and integrated sustainability score while exhibiting the shortest distance to the theoretical ideal sustainability point (p < 0.05). These findings indicate that residual methane emission represents a multidimensional biological phenotype integrating ruminal fermentation, host intermediary metabolism, productive efficiency, and environmental performance. Selecting cattle with low residual methane emissions may therefore contribute simultaneously to climate-smart beef production, improved eco-efficiency, and enhanced economic sustainability.