Effect of restricted feeding after weaning on the productive and carcass traits of growing rabbits

The aim of the experiment was to study the influence of feeding medicated or non-medicated diets followed by a feed restriction after weaning on the productive and carcass traits of growing rabbits. Half of the rabbits was fed non-medicated (NOMED: 10.65 DE/kg, CP: 16.9%, CF: 17.3%; n=106) while the other half was fed medicated diet (MED: the same diet was supplemented with 500 mg/kg Oxitetraciclyn and 50 mg/kg Tiamuline; n=108) between 4 and 9 weeks of age, then they consumed non-medicated diet. Within both diet groups half of the rabbits was fed ad libitum (ADLIB) while the other half restricted (RESTR). In the latter group rabbits were allowed to consume for 9, 10, 12 or 14 hours between 4-5, 6-7, 7-8 or 8-9 weeks of age, respectively, then they were fed ad libitum. The feed intake was 26.7, 18.3 (P<0.001) and 5.3% (P=0.059) lower in the RESTR group at the ages of 4-5, 5-6 and 6-7 weeks, respectively. After 7 weeks of age no difference was found between groups. Body weight gain of RESTR rabbits was 20.9 (P<0.001) and 8.5% (P=0.039) lower at the ages of 4-5 and 5- 6 weeks, respectively, while between 6 and 8 weeks of age it slightly increased. Body weight of RESTR rabbits was 9.2% lower at 5 weeks of age compared to ADLIB group (871 vs. 959 g) but this was partly compensated at the end of the experiment (2737 vs. 2799 g, P=0.056). Feed conversion of RESTR group was better compared to ADLIB rabbits: 2.57 vs. 2.64 (P=0.01). No significant difference was found in the mortality (1 vs. 3.6%). Dressing out percentage (59.4 vs. 58.6%, P<0.001) and the proportions of hind part (19.2 vs. 18.8%), hind legs (18.3 vs. 18.0%) and that of the m. Longissimus dorsi (7.1 vs. 6.8%) to the body weight were higher in ADLIB rabbits. No difference was found in the proportion of perirenal fat. Production and mortality of MED and NOMED groups were similar however, the feed intake and the body weight gain of MED rabbits decreased during the transition from MED to NOMED diet at 9 weeks of age. Significantly higher dressing out percentage (59.5 vs. 58.5%, P<0.001) and proportion of fore and hind parts of carcass as well as that of the hind legs and m. Longissimus dorsi to the body weight were found in MED rabbits.