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.

The objective of this study was to evaluate the effect of 3-nitrooxypropanol (3-NOP) in combination with different feed additives on growth performance, carcass traits, meat quality, enteric methane (CH₄) emissions, nutrient intake and digestibility, and blood parameters in feedlot beef cattle. In experiment (Exp.) 1, one hundred sixty-eight Nellore bulls (initial bodyweight (BW) 410 ± 8 kg) were allocated to 24 pens in a completely randomized block design. In Exp. 2, thirty Nellore bulls (initial BW 410 ± 3 kg) were allocated to a collective pen as one group, and treatments were allocated in a completely randomized design. Three treatments were applied: Control (CTL): monensin sodium (26 mg/kg of dry matter, DM); M3NOP: CTL with 3-NOP (100 mg/kg DM); and Combo: 3-NOP (100 mg/kg DM) with essential oils (100 mg/kg DM), 25-Hydroxy-Vitamin-D3 (0.10 mg/kg DM), organic chromium (4 mg/kg DM), and zinc (60 mg/kg DM). In Exp. 1, bulls in the Combo group had greater (p < 0.01) dry matter intake (DMI) at d 28 compared to the CTL and M3NOP groups. During d 0 to 102, bulls’ final BW and average daily gain (ADG) were greater (p ≤ 0.03) for the Combo group compared to the CTL. The bulls in the Combo and M3NOP groups had better (p < 0.01) feed conversion (FC) and feed efficiency (FE) compared to the CTL. Hot carcass weight (HCW), carcass ADG, and carcass yield were greater (p ≤ 0.05) for bulls in the Combo group compared to the CTL and M3NOP groups. The bulls in the Combo group had greater (p = 0.01) dressing compared to the M3NOP group. Combo bulls had better (p = 0.02) biological efficiency compared to the CTL. The bulls in the Combo group had lower (p < 0.01) carcass pH compared to the CTL and M3NOP groups. In Exp. 2, bulls in the Combo group had greater (p = 0.04) DMI at d 28 compared to the CTL and had greater (p < 0.01) DMI at d 102 compared to the CTL and M3NOP groups. The bulls in the Combo group had greater (p = 0.04) HCW compared to the CTL and M3NOP groups and carcass ADG was greater (p = 0.04) for bulls in the Combo group compared to the M3NOP group. The bulls in the Combo and M3NOP groups had lower (p < 0.01) CH₄ production (38.8%, g/d), yield (41.1%, g/kg DMI), and intensity (40.8%, g/kg carcass ADG) and higher (p < 0.01) H₂ emissions (291%, g/d) compared to the CTL. Combo bulls had lower (p < 0.01) blood glucose and insulin, and higher nutrient intake and digestibility (p ≤ 0.05) compared to the CTL and M3NOP groups. Combining 3-NOP with different feed additives improved FC and FE, and reduced enteric CH₄ emissions. Combo treatment improved growth performance, carcass traits, nutrient intake, and digestibility, and improved glucose and insulin responses in feedlot beef cattle on a high-concentrate finishing diet.

Contamination by multi-mycotoxins in cattle feed can lead to increased susceptibility to diseases and loss of performance. The present study aimed to investigate the occurrence of multiple mycotoxins present in the diet of beef cattle feedlots in Brazil. Chromatographic analyses were performed on 152 TMR samples from seven states, representing the diet provided to 1,246,522 animals. Contamination by mycotoxins was found in 100% of the TMR samples analyzed, with the most frequent being fumonisins, present in 100% of the samples, followed by zearalenone, which contaminated 79.6% of the samples, and subsequently by aflatoxins, deoxynivalenol, and T-2, while HT-2 was not detected in any of the samples. Furthermore, 2.6% of samples showed co-occurrence of five different types of mycotoxins, 23.7% presented four mycotoxins, 41.4% three mycotoxins, 22.4% two mycotoxins, and 9.9% of the samples showed contamination by only one mycotoxin. The significant prevalence of mycotoxins of the Fusarium and Aspergillus genera in the samples of the present study indicates a notable degree of pre- and post-harvest contamination in these beef cattle diets. Further studies are needed to define methods for monitoring cattle exposure to clarify its effects, even at low levels, and reduce the impacts on beef cattle production in Brazil.

The objective was to evaluate the effect of 3-nitrooxypropanol (3-NOP) in combination with different feed additives on growth performance, carcass traits, meat quality, enteric methane (CH₄) emissions, nutrient intake and digestibility, and blood parameters in feedlot beef cattle. In experiment (Exp.) 1, one hundred sixty-eight Nellore bulls (initial bodyweight (BW) 410 ± 8 kg) were allocated to 24 pens in a completely randomized block design. In Exp. 2, thirty Nellore bulls (Initial BW 410 ± 3 kg) were allocated to a collective pen in a completely randomized design. Three treatments were applied: Control (CTL): Sodium monensin (26 mg/kg of dry matter, DM), M3NOP: CTL with 3-NOP (100 mg/kg DM) and Combo: 3-NOP (100 mg/kg DM) with essential oils (100 mg/kg DM), 25-Hydroxy-Vitamin-D3 (0.10 mg/kg DM), organic chromium (4 mg/kg DM), and zinc (60 mg/kg DM). In Exp 1, bulls in Combo had greater (P<0.01) dry matter intake (DMI) at d 28 compared with CTL and M3NOP. During d 0 to 102, bulls final BW and average daily gain (ADG) were greater (P≤0.03) for Combo compared with CTL. Bulls in Combo and M3NOP had better (P<0.01) feed conversion (FC) and feed efficiency (FE) compared with CTL. Hot carcass weight (HCW), carcass ADG and carcass yield were greater (P≤0.05) for bulls from Combo compared with CTL and M3NOP. Bulls in Combo had greater (P=0.01) dressing compared with M3NOP. Combo bulls had better (P=0.02) biological efficiency compared with CTL. Bulls in Combo had lower (P<0.01) carcass pH compared to CTL and M3NOP. In Exp. 2, bulls in Combo had greater (P=0.04) DMI at d 28 compared with CTL and had greater (P<0.01) DMI at d 102 compared with CTL and M3NOP. Bulls in Combo had greater (P=0.04) HCW compared with CTL and M3NOP and carcass ADG was greater (P=0.04) for bulls Combo compared with M3NOP. Bulls in Combo and M3NOP had lower (P<0.01) CH₄ production (38.8%, g/d), yield (41.1%, g/kg DMI), intensity (40.8%, g/kg carcass ADG) and increased (P<0.01) H₂ emissions (291%, g/d) compared with CTL. Combo bulls had lower (P<0.01) blood glucose and insulin, and higher nutrient intake and digestibility (P≤0.05) compared with CTL and M3NOP. Combining 3-NOP with different feed additives improved FC, FE, and reduced enteric CH₄ emissions. Combo treatment improved growth performance, carcass traits, nutrient intake and digestibility, and improved glucose and insulin responses in feedlot beef cattle on a high-concentrate finishing diet.