Effects of Mannanoligosaccharide on Growth Performance, the Development of Gut Microflora, and Gut Function of Broiler Chickens Raised on New Litter

In search of substances to replace antibiotics as growth promoters for farm animals, mannanoligosaccharides (MOS) have been proposed as a possible alternative. In the present experiment, the influence of MOS on growth performance and bacteriological, morphological, and functional aspects of small intestine was investigated in broiler chickens at different ages. Three dietary treatments were used: a negative control without MOS or antibiotic, a positive control (Zn bacitracin), and 2 g of MOS/kg of diet. The MOS supplement tended to improve BW gain compared with the negative control in early life (P = 0.07). The counts of total anaerobic bacteria, lactic acid bacteria, and 'Clostridium perfringens' were not affected by the supplementation of MOS. The counts of coliform bacteria were increased in young birds treated with MOS. No significant differences in the gut morphology and function were noticed between the MOS treatment and the negative or the positive control at d 14, but birds in the positive control group had significantly higher jejunal villi and mucosal alkaline phosphatase activities than MOS-supplemented birds at d 35. In the current study conducted under hygienic experimental conditions, the addition of MOS did not show a clear positive effect on performance or intestinal morphology and function.