effect of single, double and multi-strain probiotics on performance, morphology of small intestine and immunological and hematological parameters of broiler chikens

probiotics are live microorganisms with beneficial health effects on host animals which exert their effects on performance, gastrointestinal tract and immune system. various probiotic products are available in the market. this study compared the effects of various probiotic products on broiler performance, intestinal morphology and some immunological and hematological parameters. five probiotic products were fed to v480 1-d old broilers for 49 days. performance was studied in starting, growing, finishing and whole periods. samples of small intestine were studied at 21, 35 and 49 days of age. antibody titers against sheep red blood cells and new castle vaccine virus determinede as immune respons of birds. probiotic type influenced the performance of birds. morphological charactertics of intestine have been affected by probiotic type. probiotic type has not been affected by immune and blood related factors (p>0.05). type and ingredients of probiotics should be considered when used for a special goal.