effect of different routes of lactobacillus rhamnosus administration in hatchery on performance, intestine morphology and serum cholesterol in experimentally salmonella infected broiler chickens.

the effects of various routes of probiotic administration on performance, small intestine morphology and serum cholesterol of broiler chickens, were studied. we assigned 225 day old chicks (ross 308) to five experimental groups including control and four hatchery administration methods comprised of in ovo injection, oral gavage, spray application and cloacal inoculation. all of these were challenged by 107 log cfu/ml se using oral gavage one day after administration of probiotics.  each treatment had three replications of 15 chicks. performance and intestine morphology were studied on weekly basis. concentration of cholesterol, hdl and ldl in serum was determined at day 21. the highest daily body weight gain and the less feed conversion coefficient was observed in cloacal administered group (p<0.05). significant effect was observed on length of villi in all 3 segments of small intestine among different routes applied for probiotic administration. in ovo injection resulted in significant improvement in length of villi in proximal segments of small intestine, duodenum and jejunum, compared to that of in the other groups except for spray group (p<0.01). length of villi in distal segment of small intestine, ileum, was higher in cloacal administered group compared to that of in the other groups (p<0.01). significant effect was observed on serum lipids among different routes of probiotic administration and the less content of cholesterol, hdl and ldl was observed in cloacal administered group (p<0.05).