03730naa a2200721 a 450000100080000000500110000800800410001902200140006010000170007424501780009126000090026952016620027865000210194065000160196165000100197765000150198765000270200265000320202965000200206165000190208165000130210065000120211365000130212565000160213865000180215465000210217265000250219365000210221865000120223965000180225165000190226965000160228865000180230465000250232265000220234765000220236965000130239165000140240465000230241865000100244165300220245165300200247365300370249365300200253065300220255065300220257265300150259465300220260965300300263165300250266165300270268665300280271365300380274165300100277970000190278970000300280870000160283870000150285470000200286970000220288970000200291177300770293119271922021-07-06       2012    bl uuuu     u00u1 u    #d  a1806-92901 aPORTO, M. O.  aNutritional requirements of energy, protein and macrominerals for maintenance and weight gain of young crossbred Nellore × Holstein bulls on pasture.h[electronic resource]  c2012  aThe 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).  aAnimal nutrition  aBeef cattle  aBulls  aCrossbreds  aDietary energy sources  aDietary mineral supplements  aDietary protein  aForage grasses  aHolstein  aNellore  aPastures  aWeight gain  aYoung animals  aBezerro mestiço  aBrachiaria decumbens  aCapim Brachiaria  aEnergia  aGado de corte  aGado Holandês  aGado Nelore  aGanho de peso  aGramínea forrageira  aNutrição animal  aNutriente mineral  aPastagem  aProteína  aSuplemento mineral  aTouro  aAnimales jóvenes  aAumento de peso  aFuentes energéticas dietéticas  aGanado de carne  aNelore x Holstein  aNutrición animal  aPastizales  aPastos forrajeros  aProductos del cruzamiento  aProteína dietética  aRaza de bovinos Nelore  aRaza de ganado Holstein  aSuplementos dietéticos minerales  aToros1 aPAULINO, M. F.1 aVALADARES FILHO, S. de C.1 aDETMANN, E.1 aCAVALI, J.1 aSALES, M. F. L.1 aVALENTE, E. E. L.1 aCOUTO, V. R. M.  tRevista Brasileira de Zootecnia, Viçosagv. 41, n. 3, p. 734-745, 2012.