RESUMO
The objective of this study was to evaluate increasing levels of inclusion of dry distillery grains (DDGs) in substitution of corn and urea in multiple supplements for beef cattle of Urochloa brizantha cv. Marandu on the consumption, digestibility, and efficiency of microbial synthesis and use of nitrogen. We used four Nellore bulls cannulated in the rumen with an average age of 24 months and 445.12 ± 34.4 kg of body weight (BW), in a 4 × 4 Latin square design. Supplements differed by the inclusion level of DDG (0%, 31.5%, 63.0%, and 94.5%). Increasing levels of DDG inclusion decreased dry matter intake (DMI) (P = 0.002), forage (P = 0.002), organic matter (OM) (P = 0.001), crude protein (CP) (P = 0.037), and total digestible nutrients (TDN) (P < 0.001) and had a quadratic effect on the intake of non-fibrous carbohydrates (NFC) (P = 0.002). It was observed an increase in the digestibility of ether extract (EE) (P = 0.005), however a decrease in the digestibility of NFC (P = 0.001). Inclusion of DDG did not influence ruminal pH. There was a quadratic effect at collection times for ruminal ammoniacal nitrogen (P < 0.05), except for the supplement with 94.5% DDG where the effect was linear (P = 0.002). Nitrogen intake was 10.9% higher when there was no DDG in the supplement, compared with the supplement with 94.5% DDG (P = 0.039). The excretion of N by feces was greater when there was a greater amount of DDG in the supplement (P = 0.027), the opposite occurred with urine excretion of N, being higher when there was less amount of DDG in the supplement (P = 0.027). Increasing levels of DDG did not affect ruminal microbial protein yield (P > 0.05). Replacing corn and urea with up to 94.5% DDGs in multiple supplements resulted in no adverse effect efficiency of microbial synthesis, although nutrient intake, total digestible nutrients, and use of nitrogen were reduced at 94.5% DDG inclusion.
Assuntos
Ração Animal/análise , Bovinos/fisiologia , Dieta/veterinária , Proteínas Alimentares/administração & dosagem , Suplementos Nutricionais , Animais , Peso Corporal , Proteínas Alimentares/análise , Digestão , Ingestão de Energia , Fezes , Masculino , Nitrogênio/metabolismo , Poaceae , Rúmen/metabolismo , Estações do Ano , Ureia/metabolismo , Zea mays/metabolismoRESUMO
The objective of this study was to evaluate the effects of rumen-protected oil (soybean and palm oil) in supplements for beef cattle during the fattening phase in pastures on the intake and digestibility of nutrients, animal performance, and carcass characteristics. Forty-eight noncastrated male Nellore cattle (15 ± 2 months and 389.5 ± 20 kg of body weight) were used in a completely randomized design to evaluate the following treatments: protein-energy supplement (PES) without rumen-protected oil (control: CO), PES containing palm rumen-protected oil (PRPO), PES containing soybean rumen-protected oil (SRPO), and PES containing a mixture of soybean and palm rumen-protected oil (SPRPO). The study lasted 112 days, and there was a decrease in crude protein intake (P < 0.05) and an increase in ether extract intake (P < 0.05) when rumen-protected oil was included in the supplements. In comparison to the palm rumen-protected oil supplement, the soybean rumen-protected oil supplement promoted a lower average daily gain (ADG) (P < 0.05); however, regardless of the rumen-protected oil source, an increase in the fat thickness of the subcutaneous tissue was observed. In addition, there was no difference in carcass gain (P > 0.05) regardless of oil source. Rumen-protected oil is a tool to increase the finishing of pasture-finished young beef cattle in the dry season.