VARIATION OF MEAT PRODUCTION CAPACITY IN CATTLE DUE TO GENOTYPE AND LEVEL OF FEEDING - GENOTYPE-NUTRITION INTERACTION

The variations of meat production capacity with genotype in cattle were studied by using comparisons between continental beef breed bulls - large sized or late maturing breeds -(Charolais, Limousin, Maine-Anjou) and dairy breed bulls (Friesian, Holstein). The particularities of the former were emphasized especially with regard to their higher muscle and protein retention capacity and better food efficiency. Thus, for the same range of body weight (350-550 kg) and the same body weight gain (1200 g/d), Limousin and Charolais young bulls produced 29 and 15% more muscle and protein, respectively, than Friesian bulls. The possible reasons for large differences in food efficiency (10-30%) are discussed. For each of these genotypes, the growth rate, the composition of gain and the food efficiency varies with the level of feeding. It has been shown that for a given body weight there is a level of energy intake and a corresponding growth rate for which the food efficiency is highest. However, this level varies with genotype. It has been concluded that (1) the comparisons between genotypes should include various feeding levels, and (2) it is necessary to adjust the energy allowances according to the genotype of animals. © 1979.