A Composite Bacillus Preparation: Effects on Intestinal Development and Immune Function of Meat Rabbits

This study was conducted to investigate the effects of composite bacillus preparation( CBP) on intestinal development and immune function of meat rabbits. A total of 160 NewZealand meat rabbits aged 35 days were randomly assigned into five groups with 4 replicates in each group and 8 rabbits per replicate( half male and half female). Rabbits in control group were fed a basal diet,those in antibiotics group were fed the basal diet supplemented with 400 mg / kg enramycin( 4%),while those in test groups 1,2 and 3 were fed the basal diet supplemented with CBP at 200,300 and 400 mg / kg,respectively. The CBP was consist of 50% B. subtilis and 50% B. licheniformis,and total live bacterial number of it was ≥1. 5 × 1010CFU / g. The test lasted for 8 weeks. The results showed as follows: intestinal content pH in test groups 1,2 and 3 were decreased, and whole intestinal content pH was significantly decrease in test group 3( P 0. 05); villus height / crypt depth in test groups 2 and 3 was significantly increased( P 0. 05); the number of E. coli and total aerobic bacteria in cecum in test groups 1,2 and 3 was significantly decreased,while that of lactobacilli,bifidobacteria and total anaerobic bacteria was significantly increased( P 0. 05); serum immunoglobulin M,complements 3 and 4 contents in test groups 2 and 3 were significantly increased( P 0. 05),meanwhile,intestinal mucosal secreted immunoglobulin A content in test groups 1,2 and 3 was significantly increased( P 0. 05). It is concluded that supplementation of CBP can promote intestinal development,stimulate the proliferation of beneficial bacteria and inhibit the harmful ones in the cecum,as well as improve immune function. It is suggested that the optimal supplemental level in meat rabbit's diet is 300 to 400 mg / kg.