Effects of probiotic-supplemented diets on growth performance and intestinal immune characteristics of broiler chickens.

This study was conducted to investigate the effects of a probiotic product incorporating Lactobacillus fermentum and Saccharomyces cerevisiae on the growth performance and intestinal immune status in broiler chickens. A total of six hundred ninety-six 1-d-old male Cobb broilers were randomly allotted by BW in 1 of 4 treatments for 6-wk trial. The dietary treatments included the basal diet (NC), and the basal diets supplemented with an antibiotic (100 mg of chlortetracycline/kg of diet; PC), 0.1%, or 0.2% probiotic product (containing 1 × 10(7) cfu/g of Lactobacillus fermentum JS and 2 × 10(6) cfu/g of Saccharomyces cerevisiae). Each treatment had 6 replicates with 29 broilers each. The ADG and feed efficiency were improved (P < 0.05) in broilers fed the probiotic diet compared with NC, and were similar to the PC group during 1 to 21 d. However, there were no significant differences in growth performance of broilers during 22 to 42 d among different dietary treatments. Chicks fed probiotics had higher proportions of CD3+, CD4+, and CD8+ T-lymphocytes, whereas the antibiotic diet decreased the proportion of CD8+ T-lymphocytes in the foregut of broilers at 21 and 42 d compared with the NC group. No significant difference was observed in the mRNA expression level of chicken B-cell marker chB6 (Bu-1) in the foregut of chickens among different treatments. Probiotic-supplemented diets increased (P < 0.05) the mRNA expression levels of Toll-like receptor (TLR) 2 and TLR 4 at 21 d, and only the TLR2 mRNA level at 42 d in the foregut of chickens, but did not change (P > 0.05) TLR7 mRNA expression compared with NC or PC. There was no significant difference in the above TLR mRNA levels in the intestine of broilers between PC and NC. These results indicated that the probiotic product incorporating Lactobacillus fermentum and Saccharomyces cerevisiae could stimulate intestinal T-cell immune system without decreasing growth performance in broilers during 1 to 21 d.