Dietary supplementation with mannanoligosaccharides and β-glucans in growing rabbits. 1. Growth performance, health status and carcass traits

A total of 384 rabbits weaned at 32 d of age were assigned to six experimental groups of 64 rabbits each, homogeneous in live weight (average and variability) and housed in individual cages. Animals fed ad libitum until slaughter (75 d) six diets which differed for the type and level of the supplemented additive: diet C without additives; diets G1 and G2 supplemented with two levels of β-glucans from Saccharomices cerevisiae (100 and 200 mg/kg, respectively); diets M1 and M2 supplemented with mannanoligosaccharides (Actigen, Alltech; 400 and 800 mg/kg, respectively); and diet GM (100 mg β-glucans + 400 mg mannanoligosaccharides/kg). Health status of animals was good (average mortality 3.5%) and both caecal fermentation traits and nutrient apparent digestibility were not affected by the inclusion level and type of additive. Growth performance of rabbits was not affected by the treatments, but daily weight gain (55.6 vs. 55.2 g/d; P=0.07) and live weight (2131 vs. 2100 g; P=0.07) values of rabbits at the end of the first period after weaning (55 d of age) were slightly higher in rabbits fed β-glucans diets compared with those fed mannanoligosaccharides diets. The slaughter traits were similar among the experimental groups. In conclusion, under the rearing conditions of the present trial and in absence of epizootic rabbit enteropathy, the dietary supplementation with mannanoligosaccharides and/or β-glucans did not produce any appreciable advantage in growth performances and carcass quality of meat rabbits.