Effects of Clostridium butyricum and selenium-enriched yeast on production performance and fecal flora structure of laying hens

【Objective】The aim of this study was to investigate the effects of adding Clostridium butyricum and seleniumenriched yeast to the diet on the production performance and fecal flora structure of laying hens, so as to provide references for improving the production performance and economic value of layer hens.【Method】Hy-line brown laying hens were used as experimental animals. The control group(CK) was fed a basal diet, while the experimental groups received the basal diet supplemented with C. butyricum and selenium-enriched yeast. The supplementation levels were as follows:T1 group added 1.0 g/kg of C. butyricum and 0.2 mg/kg of selenium-enriched yeast, T2 group added 2.0 g/kg of C. butyricum and 0.2 mg/kg of selenium-enriched yeast, and T3 group added 3.0 g/kg of C. butyricum and 0.2 mg/kg of selenium-enriched yeast. The pre-feeding period lasted for 7 d, followed by a 28 d experimental period, laying rate, average daily feed intake, average egg weight, the ratio of feed to egg and mortality rate of laying hens were measured during the period.At the end of the experiment, egg shape index, eggshell thickness, egg yolk color, albumen height, Haugh unit and egg selenium content were determined, and feces of laying hens in each group were collected and their flora structures were analyzed by bioinformatics.【Result】In terms of production performance, compared to the CK, T1 group showed a significantly increased egg production rate(P<0.05, the same below), no significant difference in average egg weight(P>0.05, the same below), and significantly decreased average daily feed intake and the ratio of feed to egg. Other groups showed slight decreases inaverage daily feed intake and the ratio of feed to egg. T1 and T3 groups had reduced mortality rates. There were no significant differences in albumen height, Haugh unit, and egg shape index among all experimental groups. The eggshell thickness and egg selenium content in T1 and T2 groups increased significantly, with the highest in T1 group. In terms of fecal flora structure, compared to the CK, T1 and T3 groups showed increases in ACE index and Chao1 index, but the differences were not significant. T1 group exhibited a decrease in Shannon index and an increase in Simpson index, but the differences were not significant. There was an upward trend in microbial richness and diversity in T1 group. At the phylum level, the dominant bacterial phyla in the CK were Firmicutes, Proteobacteria and Bacteroidetes, accounting for 74.02%, 9.14% and 7.03%, respectively. The dominant bacterial phyla in all experimental groups were Firmicutes and Proteobacteria. In T1 group, the abundance of Proteobacteria was significantly higher than in the CK, while the proportion of Firmicutes showed no significant differences with that in the CK. At the genus level, the dominant bacterial genus in both CK and the experimental groups was Lactobacillus, with no significant differences in proportion. The proportion of Lysinibacillus was significantly higher in T1 and T2 group compared to CK, while other genera showed no significant differences with that in the CK.【Conclusion】Adding C. butyricum and selenium-enriched yeast to basal diet can improve partial production performance of laying hens, while also promote the formation of a favorable intestinal flora structure in laying hens. The best feeding effect can be reached when 1.0 g/kg of C. butyricum and 0.2 mg/kg of seleniumenriched yeast are provided.