Effects of long-term Bacillus subtilis CGMCC 1.921 supplementation on performance, egg quality, and fecal and cecal microbiota of laying hens.

This study evaluated the effects of long-term Bacillus subtilis CGMCC 1.921 supplementation on the performance, egg quality, and fecal/cecal microbiota of laying hens. A total of 360 28-week-old Hy-Line Brown laying hens were randomly allocated into 5 treatments with 6 replicates of 12 birds each for 24 weeks. The experimental treatments included a basal diet without additions (Con) and the basal diet supplemented with 1.0 × 105 (B1), 1.0 × 106 (B2), 1.0 × 107 (B3), and 1.0 × 108 (B4) cfu/g B. subtilis CGMCC 1.921. The results showed that feed:egg ratio significantly decreased (P < 0.05) in groups B1 (wk 13 to 16, 17 to 20, 21 to 24, and one to 24), B2 (wk 13 to 16, 17 to 20, and 21 to 24), B3 (wk 13 to 16, 17 to 20, 21 to 24, and one to 24), and B4 (wk 13 to 16, 17 to 20, 21 to 24, and one to 24). However, egg production, egg weight, and feed intake were not significantly different (P > 0.05) among treatments. Eggshell strength significantly improved (P < 0.05) in groups B1 (wk 8, 16, 20, and 24), B2 (wk 20 and 24), and B3 (wk 8, 16, 20, and 24). Fecal E. coli counts significantly decreased (P < 0.05) in groups B1 (wk 16), B2 (wk 12, 16, 20, and 24), B3 (wk 12, 20, and 24), and B4 (wk 16, 20, and 24). Lactobacillus in cecal digesta of groups B1, B3, and B4 increased significantly (P < 0.01). Bifidobacterium in cecal digesta of groups B1, B2, B3, and B4 increased significantly (P < 0.05). Bifidobacterium counts increased linearly (P = 0.015) and quadratically (P = 0.004) as B. subtilis CGMCC 1.921 supplementation increased. Compared with Con, E. coli in the cecal digesta of groups B2 and B4 decreased significantly (P < 0.01). C. perfringens in the cecal digesta of groups B3 and B4 decreased significantly (P < 0.05). E. coli:Lactobacillus ratio decreased in group B1 (P < 0.05) and B2, B3, and B4 (P < 0.01). Therefore, the probiotic B. subtilis CGMCC 1.921 effectively improved performance and egg quality via the reduction of fecal E. coli and beneficial modulation of cecal microbiota.