Effect of supplementation with Beta-glucan of saccharomyces cerevisiae and chito-oligosaccharides on digestion and growth performance in weaning

The aim of this work was to study the effect of yeast Beta-glucans and chito-oligosaccharides supplementation on digestion and growth performance of growing rabbits. Five experimental diets were prepared. A control diet was formulated with 18.1 per cent protein, 33.1 per cent neutral detergent fibre and 13 per cent soluble fibre (on DM basis). Another four diets were obtained by supplementing control diet with Beta-glucans (200 or 400 ppm. BG2 and BG4) and chito-oligosaccharides (200 or 400 ppm. OT2 and OT4). No antibiotic was used. In the first experiment, 56 rabbits per treatment weighing 510 plus minus 73.0g weaned at 28 d of age were used to record mortality, and in 42 rabbits per treatment growth traits were recorded. Rabbits fed control, BG4 and OT4 diets (42 per treatment), were used to determine the body composition by bioelectrical impedance technique measured at 28, 38 and 63 d of age. Experimental diets were offered from weaning up to 38 d of age. At this moment all rabbits were fed the control diet up to 63 d of age. Another group of 24 rabbits per treatment received from 28 to 38 d of age the five diets containing mordanced ytterbium. They were slaughtered at 38 d of age and ileal digesta collected to quantify ileal digestibility and caecal pH recorded. Faecal digestibility was measured from 36 to 38 d of age (9rabbits per diet). In the second experiment, three hundred thirty-four rabbits were separated from their mothers at 19 d of age (329 plus minus 65g) and assigned to the control, BG4 and OT4 diets. Rabbits suckled every morning for 10 minutes until 28 d of age. After weaning at 28 d of age, two hundred thirty-one rabbits received the same experimental diets than in the first period (77 rabbits per diet) and were caged individually to determine growth performance. At 19 d of age, 10 rabbits from 10 different litters were slaughtered to determine the digestive parameters (relative weight of total digestive tract, stomach and caecum).At 27 and 38 d of age 30 rabbits (3 rabbits per treatment and litter) from each of the same 10 litters which have been chosen before (at 19 d of age) were slaughtered to determine the same measurements. Diet supplementation with Beta-glucans and chito-oligosaccharides did not affect ileal and faecal DM digestibility and faecal digestibility of fat, protein and fibre. Similarly, no treatment effect was found on growth traits along fattening period in the two experiments. In the first experiment, the mortality increased in rabbits supplemented with 200 ppm Beta-glucans compared to 400 ppm Beta-glucans (P equal to 0.048).In the second experiment, the mortality rates were lower than in the first one, and there were no other effect of treatments. The type of diet did not modify the retention and efficiency of both nitrogen and energy in the whole animal or in the carcass. However, rabbits fed supplemented diets with chito-oligosacchharides showed a higher faecal excretion of nitrogen (P equal to 0.034) and energy (P equal to 0.076) between 28 and 38d of age. Treatments had no effect on the relative weight of digestive organs. In conclusion, in our condition the supplementation of Beta-glucans and chito-oligosaccharides does not provide any advantage to growing rabbits