Abstract

A study was conducted to evaluate the effects of mannan-oligosaccharides (MOS) on cecal microbial populations, immune responses to phytohaemagglutinin-P (PHA-P) and sheep red blood cell (SRBC) and performance (weight gain and feed conversion ratio) of broiler chicks under strict controlled condition. Sixty four day-old male broiler chicks were randomly assigned to 12 battery cages pens of 4 chicks each and were fed from 1 to 42 days of age. Two basal diets were formulated for starter (1 to 21 days) and grower (22 to 42 days) period and a graded level of MOS (0.5, 1 and 1.5 g/kg) were added to basal diet to make diets 2 to 4. Body weight gain and feed conversion ratio were measured at 21, 35 and 42 days of age. Immune response to PHA-P was measured at 35 and to SRBC at 28 and 42 days of age. Cecal contents were assayed for lactobacilli and Escherichia coli at 42 days of age. Plasma triglyceride, cholesterol and HDL concentration was measured at 42 days of age. Body weight gain and feed conversion ratio did not differ among dietary treatments. Carcass, breast, tight, gizzard, duodenum, jejunum and ileum relative weight and duodenum, jejunum and ileum relative length were not affected by treatments. MOS increased immune response to PHA-P and SRBC numerically. Plasma triglyceride and HDL concentration did not differ among the treatments but plasma cholesterol concentration decreased linearly by adding MOS to the basal diet (P<0.05). Results showed no significant differences in lactobacilli and E. coli content of ceca among the treatments. Results of this experiment showed that MOS could affect the immune response and performance and as well as plasma cholesterol regardless of strict controlled condition.

Key words: Mannan-oligosaccharides, broiler chicks, performance, immune response, plasma factors.