Post-weaning maturation of rabbit caecal microbial communities: impact of live yeast intake
Résumé
The aims of this work were first to evaluate nutritional requirements of early weaned kits (23 days of age), more especially fibre (experiment 1) and protein (experiment 2) needs. In experiment 1, 276 early weaned rabbits were offered from 23 to 50 days of age one of the three experimental diets containing increasing acid-detergent fibre level (160, 190 or 220g/kg). Fibre was substituted by starch and fat to obtain three isoenergetic diets. In experiment 2, 306 early weaned rabbits were offered from 23 to 50 days of age one of the three experimental diets containing increasing crude protein (CP) level (150, 180 or 210g/kg). Protein was substituted by starch and fat to obtain three isoenergetic diets. These studies revealed no effect of the dietary fibre level and the dietary CP level on health status. But from 23 to 36 days of age rabbits given diets containing a fibre level over 190g/kg or a CP level under 180g/kg showed the lowest growth rate as compared with other respective treatments. Secondly, this research aimed to evaluate the interaction between age at weaning (23 days or 35 days of age) and food (RD and RY diets) on digestive health and performances of young rabbits (experiment 3). RD diet was formulated to contain (per kg) 170g starch, 160g fibre and 180g CP (according to the nutritional requirements of does) and RY diet was formulated to reach 110g starch, 160g fibre and 210g CP (according to the results of experiments 1 and 2). 39 litters of nine pups per litter were assigned at 18 days of age to one of four experimental groups in a 2×2 factorial design: RD23 (no. =84 rabbits), RY23 (no. =85 rabbits), RD35 (no. =86 rabbits) and RY35 (no. =74 rabbits). Food intake and live weight were not influenced by feeding strategy. Between 23 and 35 days of age, mortality was higher in RY than in RD group (20·4 v. 6·8% respectively; P<0·05). During this period growth rate was proportionately 0·584 higher in conventionally weaned than in early weaned rabbits (P<0·001). After 35 days of age, food intake and growth rate were proportionately 0·104 and 0·097 higher respectively in conventionally than in early weaned rabbits (P<0·05). Consequently, live weight was higher in conventionally weaned rabbits at both 35 and 53 days of age (proportionately +0·113 and +0·267 respectively; P<0·001). Mortality rate between 23 and 35 days was 21 points higher (P<0·001) in early weaned than in conventionally weaned pups and 43 points higher (P<0·001) from 35 to 53 days of age. These data suggest that the removal of milk feeding by early weaning leads to detrimental effects on health and growth of the young, which were not compensated by a diet meeting better their nutritional needs.