Body composition of the rabbit. Factors of variation

Abstract

In specialized rabbit breedings, the production of one female is in the order of 45 slaughtered rabbits per year, i.e. 60 kg of meat. These rabbits, normally the size of an average adult (4 kg), supply in 10 to 11 weeks a carcass of 1.3 kg of which the best quality cuts (83 % of the carcass), 85 % edible, are particularly lean (less than 3 % of fatty tissue). The species is rich in breeds of different size. These offer a significant potential for qualitative diversification of meat. In particular, the giant breeds are of interest to the extent that selected cuts and processing are developing sectors. The main butchering characteristics of the rabbit : slaughter yield, muscle/bone ratio and possibly adiposity may be improved by pure breed selection. Genetic progress which may also be obtained on growth rate will normally be accompanied by an increase in the glycolytic way of the muscular energy metabolism and hence in a decrease in meat quality. Improval in the growth rate of young rabbits, obtained by increasing the proteinic level in their ration leads to the same changes in muscular energy metabolism. When the growth rate of young rabbits is improved, either by better nutritional balance (especially protein/energy), or by an increased food supply (feeding at will, minimum roughage proportion), the proportions of precocious tissue (digestive tract, skeleton and possibly skin) are reduced, those of later-developing tissues (muscular tissue and especially adipose tissue) are increased. This results in improved slaughter yield, muscle/bone ratio and adiposity. In the rabbit, a monogastric herbivore, food lipids have very significant effect on the characteristics of body fats. The increase in fat supply, for the purpose of raising the energy level in the ration without lowering that of the undigestible glucides, has to be perfected in order to prevent qualitative accidents related to thermic or chemical instability of fatty acids.