Effect of feeding programme on growth and body balance of meat rabbits

Two feeding systems (L, ad libitum vs. R, feed restriction) were combined with three feeding plans (HH, MM, MH) to evaluate the effects on performance, slaughter results and nitrogen balance of 300 commercial crossbred rabbits kept individually from weaning to slaughter (34-70 d of age). Feed restriction ranged from 80% to 100% of ad libitum intake from the beginning of the trial until the end of the 3rd week. The three feeding plans were: 1) HH, H diet with high digestible energy content, 11.1 MJ DE/kg, during the whole trial; 2) MM, M diet with moderate DE, 10.6 MJ/kg, during the whole trial; 3) MH, M diet during the first three weeks and H diet during the last two weeks. Feed restriction did not affect health status, nutrient digestibility, growth rate and slaughter results, but improved feed conversion (2.96 vs. 2.89 in L and R rabbits, respectively; P<0.01) and reduced N excretion (2.15 vs. 2.07 g excreted N/d, in L and R rabbits; P<0.05). At the end of the first period (55 d), R rabbits showed lower empty body protein, lipid, and gross energy gains than L rabbits, but differences disappeared within the end of the trial. The high- energy feeding plan (HH) improved feed conversion (2.89 vs. 2.93 and 2.97 for HH, MH and MM, respectively; P<0.05), but increased excreted N (2.17 and 2.12 vs. 2.03 g/d; P<0.001) because of the higher DP/DE ratio of H diet. In conclusion, a moderate feed restriction during post weaning improved feed conversion and reduced N excretion without negative effects on growth or slaughter results. Besides, N excretion was confirmed to depend largely on dietary nitrogen content.