Effect of a mannan oligosaccharide used as a food additive for broilers.

This experiment was carried out to determine the effect of an additive based on a mannan oligosaccharide in the nutrition of broilers during the first 43 days of their life. The experiment was performed in a commercial farm in the region of Valencia (Spain). A total of 720 broilers divided into groups of 60 were each placed in 4 m pens (2x2 m), thus maintaining the same animal density as in the rest of the farm. Half the animals (6 pens) were given standard feed, whereas the other half were fed the same food supplemented with the additive at a rate of 500 g/t. Throughout the study mortality and morbidity were assessed daily. On days 1, 22 and 43, the weight of the broilers was recorded and samples were obtained to investigate the presence of oocysts, the presence of bacterial pathogens and to assess the integrity of the intestine mucosa. During the first three weeks, we detected differences between the two groups of broilers, in terms of average daily gain (ADG) and feed conversion rate (FCR); ADG (41.95 vs 43.26; p<0.05) and FCR (1.82 vs 1.76; p<0.05) were better in broilers fed the standard feed than those receiving the additive. However these differences were not significant when the whole period of study was considered. We found no effects either in the number of Eimeria oocysts or infections by Salmonella or other pathogens. No differences were detected on mortality and morbidity between the two groups.