Different combinations of probiotics improve the production performance, egg quality, and immune response of layer hens.

To evaluate the effects of different combinations of probiotics on performance, egg quality, and immune response of layer hens, a trial was carried out with 1,800 white feather layer hens of the Lohmann variety. The experiment was conducted by using a completely randomized design with 9 treatments, 4 replicates, and 50 hens in each replicate. Compared with the control group, group F, which added a composition of heat-inactivated Lactobacillus salivarius(CB) and Bacillus subtilis to the diets of layer hens, caused highly significant (P < 0.05) increases in egg production, daily egg yield, damaged egg ratio, combined with a significant (P < 0.05) decrease in feed conversion and damaged egg ratio. Group G, adding a combination of inactivated Lactobacillus salivarius and sodium butyrate, resulted in a significant increase (P < 0.05) in daily egg yield, feed conversion, damaged egg ratio and Haugh unit. Meanwhile, groups D and H had significantly decreased feed conversion (P < 0.05), and groups B, H, and I had a significantly decreased damaged egg ratio. In serum levels, no significant difference was observed except a significant decrease (P < 0.05) in total cholesterol (groups D, E, and G) and low-density lipoprotein cholesterol (group E and G) and a significant increase (P < 0.05) in total cholesterol (groups D, E, and G) compared with group A. According to the hemagglutination inhibition test, the antibody titer of antibody against the avian influenza virus was significantly (P < 0.05) higher in most treated groups such as groups B, C, E, G, and I after d 15 fed to layers with probiotics and groups B, C, D, E, F, G, and H after d 45 compared with the control group. No significant difference was observed in the antibody titer against the Newcastle disease virus at d 15, but significantly (P < 0.05) higher at d 45 in groups F and G. These results demonstrate that several combinations of probiotics used in this experiment have a positive impact on the performance, egg quality, and immune response of layer hens, and the following work will continue to focus on these groups.