Effect of feed restriction and different crude protein sources on the performance, health status and carcass traits of growing rabbits

We evaluate the effect of the crude protein source (CP) in combination with 2 feeding strategies (AL: ad libitum or R: restricted) on the performance, health status and carcass traits of growing-fattening rabbits (between 33 and 75 d of age). Two experimental diets were formulated; the first containing soybean meal (SBM: 70 g/kg) as the main CP source and the second containing white lupin seeds (WLS: 105 g/kg) as the main CP source. A total of 160 weaned Hyplus rabbits (774±10 g live weight) were randomly allocated to the experimental groups, combination of feeding strategy and diet (AL SBM, R SBM, AL WLS and R WLS; 40 rabbits per group with 4 rabbits per cage), for 42 d. The feeding programme was applied as follows: both the AL SBM and AL WLS rabbits were fed ad libitum for the entire fattening period, whereas the R SBM and R WLS rabbits were subjected to feed restriction between 33 and 47 d of age (75% of the ad libitum intake). Afterwards, all restricted rabbits were fed ad libitum until 75 d of age. Regardless of the CP source, the feed restriction reduced the final live weight by 83 g, chilled carcass weight by 65 g, and dressing out percentage by 0.9 percentage points (P<0.05). There was a higher chilled carcass weight (+114 g; P=0.001) and reference carcass weight (+91 g; P=0.001) in rabbits fed with WLS diet than in rabbits fed with SBM diet. No dead or morbid rabbits were observed in restricted rabbits during the restriction period. There was no effect of the diet on the health of rabbits. However when the rabbits of AL SBM and AL WLS group were compared did we observe a lower number of rabbits at sanitary risk in AL WLS group (2 vs. 12 rabbits, P=0.006). In conclusion, the growth performance was not affected by the crude protein source, and no interaction between dietary CP source and feeding regime was observed. Feed restriction regime did not improve sanitary risk index throughout the entire period.