Effects of the Use of a Combination of Two Bacillus Species on Performance, Egg Quality, Small Intestinal Mucosal Morphology, and Cecal Microbiota Profile in Aging Laying Hens

Sixty-week-old Hy-Line brown laying hens were randomly divided into five groups and fed different diets over a period of 84 days. Experimental treatments included a basal diet (control); the basal diet supplemented with 1.0 × 10 6 B. licheniformis yb-2 14245; the basal diet supplemented with 1.0 × 10 6 B. subtilis yb-1 14246; a combination of both strains in a 2:1 ratio (6.6 × 10 5 :3.3 × 10 5 B. licheniformis yb-2 14245: B. subtilis yb-1 14246); and the latter, added with 5 mg/kg flavomycin. Basal diet supplementation with the combined Bacillus species improved egg-laying performance in aging hens significantly ( P