The objective was to evaluate the effects of including high-protein distillers dried grains (HP-DDG; 430 g/CP) in supplements for beef cattle in an intensive finishing pasture system. Five Nellore bulls with an average body weight (BW) of 413.5 ± 32 kg were distributed in a 5 × 5 Latin square design. The animals were randomly allocated to Marandu palisade grass paddocks (Urochloa brizantha cv. Marandu), with 0.32 ha each. Protein-energy supplements were evaluated and formulated with different replacement levels (0, 250, 500, 750 and 1000 g/kg) of soybean meal (SBM) by HP-DDG. Supplements were offered once a day in the amount of 6.0 kg/animal. Replacing SBM with HP-DDG had no effect (p > 0.10) on the intake of total and pasture DM, OM, CP, NDFap, digestible organic matter (DOM), metabolizable protein and CP:DOM ratio. Total and pasture DM intake averaged 6.07 and 11.54 kg/day, respectively. Replacing SBM with HP-DDG reduces and increases, respectively, the intake of degradable (RDP) and undegradable (RUP) protein in the rumen (p < 0.10) with a consequent linear reduction in ruminal ammonia concentration (RAN), nitrogen excretion in urine and serum N concentration (SUN) (p < 0.10). In supplements offered in the amount of 6.0 kg animal/day, SBM can be completely replaced by HP-DDG.

Pasture-based beef cattle production systems aim to maximize the interaction between forage and supplements to increase activity. In addition, supplementation and the use of food additives help optimize production efficiency and improve the use of additional nutrients. The aim of this study was to evaluate the effects of the use of additives in protein–energy supplements (PESs) on the intake, digestibility, and ruminal parameters of beef cattle raised on pasture in the rearing phase. Five male cattle were allocated to a 5 × 5 Latin square design, with five experimental periods and five treatments. The animals were kept under continuous grazing in individual paddocks of marandu palisadegrass (Urochloa brizantha cv. Marandu). The treatments consisted of a mineral mixture (MM) (0.080 kg/animal/day), PES (4.0 kg/animal/day), PES with monensin sodium (120 mg/animal/day), PES with functional oil (2500 mg/animal/day) and PES with active yeast (4000 mg/animal/day). PESs increased the total dry matter intake (DMI) (kg/day) and the DMI in terms of % body weight (%BW) and increased the intake of crude protein (CP) and the dry matter intake of digestible organic matter (DOM). The use of additives did not affect nutrient intake or digestibility. Compared with MM, the PES increased the concentrations of ruminal ammonia nitrogen and serum urea nitrogen. In addition, there was an increase in fecal nitrogen, retained nitrogen, microbial nitrogen synthesis and microbial efficiency. The use of monensin sodium, functional oil and active yeast in protein–energy supplements for beef cattle in pastures did not affect the nutritional parameters under the conditions observed in this study.

This study aimed to evaluate the effect of bromoform (CHBr₃) dose on in vitro rumen fermentation and on CHBr₃ and dibromomethane (CH₂Br₂) concentrations in solution and the gas cap. In vitro treatments consisted of CHBr₃ (DOSE: 0, 1, 10, 100, 1000, 10,000 µg of CHBr₃), with five replicates per DOSE at each time-point (TIME: 0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 12, 24, 48, and 72 h). The 10,000 µg CHBr₃ DOSE inhibited fermentation completely and was removed from the dataset. The acetate:propionate ratio, nitrogen, and methane (CH₄) produced per gram of DMD decreased as DOSE increased (p = 0.01). As the DOSE increased, CH₄ decreased, and H₂ increased in a dose-dependent manner (p < 0.01). The CHBr₃ concentration dropped below the detection limit within 3 h of incubation. Dibromomethane concentrations for DOSE 1000 and 100 µg of CHBr₃ increased in solution and gas cap beginning at 0.25 h and 1 h post incubation and plateaued by hour 3 and 5, respectively (p < 0.01). The addition of CHBr₃ alters the molar proportion of volatile fatty acids, decreases CH₄, and increases H₂ production, and it is dehalogenated to CH₂Br₂ within 3 h of incubation in an in vitro system.