Mannan oligosaccharides as growth promoter in finishing rabbit: effect on in vivo performance and carcass traits

Four groups each consisting in 440, 60 days old rabbits, were fed, respectively, four experimental diets: (1) MOS_0.5 (Bio-Mos (R) at 0.5 g/kg); (2) MOS_1.0 (Bio-Mos (R) at 1.0 g/kg); (3) MOS_1.5 (Bio-Mos (R) at 1.5 g/kg) and (4) antibiotics (AGP, colistin sulphate 144 mg/kg; tylosin 100 mg/kg and oxytetracyclin 1000 mg/kg). Up to slaughter age (82 days of age) mortality rate was recorded daily. For each group, 64 rabbits were controlled weekly for live weight to calculate daily weight gain (DWG). Feed intake (and, by consequence feed conversion ratio) was measured, weekly, per group. At 82 days 16 rabbits per group were slaughtered and carcass traits were recorded. No differences were recorded among groups in live weight at different age and in daily weight gain but, in particular during the last week, AGP and MOS_0.5 groups showed higher feed intake and less favourable feed conversion ratio. MOS_1.0 group showed significantly higher incidence of empty gastro-intestinal tract but not differences were found for dressing out percentage. Perirenal fat showed a lower incidence in MOS than in AGP groups.