Effect of energy restriction in interaction with genotype on the performance of growing rabbits I: Productive traits

Abstract: The aim of this experiment was to study the effect of genotypes (rabbits selected for high or low body fat content) and level of DE intake (high, medium or low) at constant CP, CF, and EE intake on the performance of growing rabbits, separately and their interactions. Pannon White rabbits selected for high (HFAT) or low (LFAT) total body fat content were weaned at 4 weeks of age and fed one of three isocaloric diets (11.72, 11.60 and 11.66 MJ DE/kg diet, respectively). Diet one was fed ad libitum (treatment H), while diets 2 (treatment M) and 3 (treatment L) were fed at 90% and 80%, respectively of the ad libitum intake. Proportional to the reduction of feed intake the nutrient density of diets was increased (e.g. crude protein: 17.5, 19.8 and 21.9%; crude fibre: 12.9, 13.4 and 14.7%, respectively for the 3 diets). Genotype had a significant effect on feed conversion (3.26 and 3.02 g/g; P <0.001; in groups HFAT and LFAT, respectively). With the reduction of the DE intake the daily weight gain and the body weight at 12 weeks of age decreased significantly (40.7, 38.5 and 33.7g/day, P <0.001 and 2917, 2799 and 2527 g, P <0.001; in groups H, M and L, respectively). On the contrary, the energy reduction had a positive effect on the feed conversion and on the mortality rate (3.29, 3.17 and 3.11 g/g, P <0.05, and 29.5, 28.1 and 4.8%, P <0.05; respectively). It is concluded that the genotype influenced mainly the feed conversion with higher nutrient demand for building fat than for muscle. The performance (weight gain, body weight and feed conversion) was determined by the digestible energy intake, independently of nutrient intake. The effect of reductions of DE intake was independent of the genotype (rabbits with higher or lower body fat content). [Copyright &y& Elsevier]