Variations of net requirements for cattle growth with liveweight, liveweight gain, breed and sex

Abstract

To cite this version: J. Robelin, R. Daenicke. Variations of net requirements for cattle growth with liveweight, liveweight gain, breed and sex. Annales de zootechnie, INRA/EDP Sciences, 1980, 29 (hors-série), pp.99-121. ï¿¿hal-00888037ï¿¿ Variations of net requirements for cattle growth with liveweight, liveweight gain, breed and sex Abstract The main sources of variation in body and body gain composition of cattle-body weight, breed, sex, growth rate-are analysed in relation with the net requirements for growth. There is a close relationship between proteins and fat free mass. Therefore, the variations in lipids will be emphasised.-Variations with body weight : the lipid content of empty body weight gain rises very rapidly from 16 to 42 per cent with increasing empty body weight from 200 to 500 kg in early maturing bulls, fed almost ad libitum. Simultaneously the protein content of gain decreases from 19 to 14 per cent.-Variations with breed : at the same empty body weight, say 350 kg, the lipid content of empty body weight gain varies between breeds, from 15 per cent in late maturing breed bulls to 28 per cent in early maturing breed bulls.-Variations with sex and castration : the percentage of lipids in the empty body weight gain of steers and heifers is 1.5 times as high as in bulls.-Variations with growth rate : when the level of energy intake is increased, the daily lipid increases nearly twice as fast as the growth rate. All these sources of variation are carefully analysed on the basis of a large number of data. This analysis leads to a model for evaluation of net requirements for cattle growth. Résumé Variations des besoins nets pour la croissance chez les bovins