Nutritional requirements of energy, protein and macrominerals for maintenance and weight gain of young crossbred Nellore × Holstein bulls on pasture.

• Autor(a) principal: PORTO, M. O.
• Data de Publicação: 2012
• Outros Autores: PAULINO, M. F., VALADARES FILHO, S. de C., DETMANN, E., CAVALI, J., SALES, M. F. L., VALENTE, E. E. L., COUTO, V. R. M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
• Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/927192
• topic: Nelore x Holstein; Animales jóvenes; Aumento de peso; Fuentes energéticas dietéticas; Ganado de carne; Nutrición animal; Pastizales; Pastos forrajeros; Productos del cruzamiento; Proteína dietética; Raza de bovinos Nelore; Raza de ganado Holstein; Suplementos dietéticos minerales; Toros; Gado de corte; Nutrição animal; Pastagem; Gramínea forrageira; Capim Brachiaria; Brachiaria decumbens; Suplemento mineral; Nutriente mineral; Proteína; Energia; Ganho de peso; Touro; Bezerro mestiço; Gado Nelore; Gado Holandês; Beef cattle; Animal nutrition; Pastures; Forage grasses; Dietary mineral supplements; Dietary energy sources; Dietary protein; Weight gain; Young animals; Crossbreds; Bulls; Nellore; Holstein

The objective of this study was to estimate requirements of energy, protein and macrominerals of young Nellore/Holstein crossbreds bulls supplemented on pastures of Brachiaria decumbens Stapf. Thirty-five young bulls, at 8.53±0.18 months of age and with initial body weight of 230.6±6.1 kg were used. Ten animals were slaughtered as reference, in different weight range, and the other animals were slaughtered at the end of the experimental period. For estimate of net energy requirements for weight, a regression equation between log of retained energy (RE) and log of empty body weight gain (EBWG) was constructed. Net requirements of Ca, P, Mg, Na and K were determined by the equation Y' = a.b.Xb-1, in which a and b represent the intercept and the coefficient of equation of prediction of macrominerals in body content, respectively. Requirements of metabolizable energy for maintenance (MEm) were obtained from retained energy in function of metabolizable energy intake (MEI). The requirements of MEm of Nellore/Holstein crossbreds young bulls on pasture was 125 kcal/EBW0.75/day. The efficiency of ME utilization for maintenance (km) of grazing Nellore/Holstein crossbred young bulls was 0.58 and 0.24 for gain. The total metabolizable protein requirements for an animal with 400 kg and with average daily gain of 1.0 kg, were 638.36 g/day. The dietetic requirements of Ca and P for an animal with 400 kg BW were 0.49 and 0.21% of DM, respectively. Daily metabolizable energy requirement for maintenance of grazing Nellore/Holstein crossbred young bulls was 11.6% greater than the values found for cattle in feedlot in Brazil (112 kcal/kg EBW0.75).