Abstract
The study aimed at evaluation the effect of mannanoligosaccharides (MOS) and zinc-bacitracin (ZnB) administered continuously (+) or intermittently (+/-) upon growing performance, carcass and meat traits, blood profile and tissue morphology of growing rabbits. One hundred and twenty five, 25 days-old rabbits were distributed among 5 groups fed the same basal diet: the control group did not receive any supplements; MOS+ group fed mannanoligosaccarides at 0.083 g/rabbit/day; MOS+/- group fed MOS at the same concentration as MOS+ group, but only two days/week; ZnB+ group received Zinc bacitracin at 0.083 g/rabbit/day; ZnB+/- group fed ZnB at the same level as ZnB+ group but only two days/week. The experiment lasted from day 25 to 81 of life. The mortality rate in the control group (36%) was higher (P<0.05) than in MOS+/- (12%) and ZnB+ groups (12%). MOS and ZnB administered intermittently increased (P<0.01) dressing percentage as compared to the control group. The liver percentage increased (P<0.01) due to use of MOS (+ or +/-) and ZnB (+). ZnB (+ or +/-) increased (P<0.05) the protein percentage of meat as compared to the control group, while the continuative administration of MOS was able to reduce (P<0.05) the fat percentage as related to the control group. Both supplements and both administration protocols increased (P<0.01) meat tenderness and water holding capacity in respect to the control group. Continuous ZnB administration had deleterious effects on liver, kidney and ileum morphology. MOS could replace ZnB from weaning to slaughter age of rabbits without negative effects on performance and blood profiles causing no alterations in tissue morphology as compared to the control group. In addition, the MOS can be administered intermittently, reducing the production costs.