RESUMEN
The aim of this study was to develop and validate regression models to predict the chemical composition and ruminal degradation parameters of corn silage by near-infrared spectroscopy (NIR). Ninety-four samples were used to develop and validate the models to predict corn silage composition. A subset of 23 samples was used to develop and validate models to predict ruminal degradation parameters of corn silage. Wet chemistry methods were used to determine the composition values and ruminal degradation parameters of the corn silage samples. The dried and ground samples had their NIR spectra scanned using a poliSPECNIR 900-1700 model NIR sprectrophotometer (ITPhotonics S.r.l, Breganze, IT.). The models were developed using regression by partial least squares (PLS), and the ordered predictor selection (OPS) method was used. In general, the regression models obtained to predict the corn silage composition (P>0.05), except the model for organic matter (OM), adequately estimated the studied properties. It was not possible to develop prediction models for the potentially degradable fraction in the rumen of OM and crude protein and the degradation rate of OM. The regression models that could be obtained to predict the ruminal degradation parameters showed correlation coefficient of calibration between 0.530 and 0.985. The regression models developed to predict CS composition accurately estimated the CS composition, except the model for OM. The NIR has potential to be used by nutritionists as a rapid prediction tool for ruminal degradation parameters in the field.
Asunto(s)
Ensilaje , Zea mays , Animales , Ensilaje/análisis , Espectroscopía Infrarroja Corta , Rumen/metabolismo , Digestión , Fermentación , DietaRESUMEN
OBJECTIVE: This study was realized to evaluate the effects of supplementation with blends of water and fat-soluble vitamins on animal performance and carcass traits of young Nellore bulls. METHODS: Forty-three Nellore bulls, with an initial weight of 261±27.3 kg and a mean age of 8±1.0 months, were used. Five animals were slaughtered at the beginning of the experiment (reference group), to determine the initial empty body weight of the bulls that remained in the experiment. The remaining 38 bulls were fed ad libitum and distributed in a completely randomized design in a 2×2 factorial scheme, with or without supplementation of water-soluble (B-blend+ or B-blend-) and fat-soluble (ADE+ or ADE-) vitamin blends. Diets were isonitrogenous (120 g of crude protein/kg dry matter [DM] of total mixed ration) and consisted of a roughage:concentrate rate of 30:70 based on total DM of diet. The experiment lasted 170 days, with 30 days of adaptation and 140 days for data collection. At the beginning and end of the experimental period, the bulls were weighed to determine the average daily gain. To estimate the apparent digestibility of nutrients and microbial efficiency, spot collections of feces and urine were performed for five consecutive days. RESULTS: DM, ashes, organic matter, crude protein, ethereal extract, neutral detergent fiber corrected for residual ash and residual nitrogenous, and N intake and apparent digestibility were not influenced by vitamin supplementation, but total digestible nutrients intake and non-fibrous carbohydrates digestibility were influenced by B complex vitamin supplementation. Nitrogen balance, microbial efficiency, and performance data were not influenced (p>0.05) by vitamin supplementation. CONCLUSION: Vitamin supplementation (a blend of water-soluble and fat-soluble vitamins or their combinations) does not influence the animal performance and carcass traits of young Nellore bulls.