Effects of chicken-derived compound probiotics on immunoglobulin and Toll-like receptor pathway of broilers

Objective  To investigate the effects of probiotics on serum immunoglobulin and intestinal Toll-like receptor pathway in broilers.

Method  Ninety one-day-old white feather chicks were randomly divided into three groups including control group, low-dose probiotic group and high-dose probiotic group. The chicks in control group were fed basal diet, 10⁹ cfu probiotics per kg basal diet were added in the low-dose probiotic group, and 2×10⁹ cfu probiotics per kg basal diet were added in the high-dose probiotic group. On the 21st day, ten chicks in each group were sacrificed by bloodletting, and the samples were collected immediately for ELISA, immunohistochemistry, qPCR and Western blot.

Result  Compared with the control group on the 21st day, the feed conversion ratios of low- and high-dose probiotic groups decreased by 9% and 12% (P<0.05), the IgG levels in serum increased by 28% and 40% (P<0.01), and the IgM levels in serum increased by 44% and 58% (P<0.01) respectively. The protein and mRNA expression of TLR4 increased by 33% and 28% respectively in low-dose probiotic group (P<0.01), and the protein and mRNA expression of AP-1 increased by 106% and 67% respectively in low-dose probiotic group (P<0.01). The protein and mRNA expression of TLR4 increased by 106% and 69% respectively in high-dose probiotic group (P<0.01), and the protein and mRNA expression of AP-1 increased by 163% and 98% respectively in high-dose probiotic group (P<0.01).

Conclusion  Feeding probiotics can reduce the feed conversion ratio in broilers, increase the levels of IgG and IgM in serum, and enhance the immunity by regulating the expression of Toll-like receptor pathway proteins.