Impacts of Bacillus probiotics on productive performance and egg quality criteria in laying Japanese quails

The present study aimed to determine the effects of adding Bacillus megaterium and Bacillus amyloliquefaciens to laying quail diets on performance, egg quality, and internal organ weights. We used 96 laying Japanese quail (Coturnix coturnix Japonica) at 12 wk of age. The birds were divided into 3 treatment groups (32 quails per group), each divided into 8 replicates (4 quails per replicate). The research was carried out in 3 periods of 28 d each. We used 3 diets; the 1st group served as a control group, receiving only a basal diet. The 2nd and 3rd experimental groups received 0.1% (1×10⁹ CFU/g) B. megaterium and B. amyloliquefaciens as an addition to the basal diet, respectively. Adding B. megaterium and B. amyloliquefaciens did not influence the performance parameters statistically. Also, adding B. megaterium and B. amyloliquefaciens significantly (p < 0.05) impacted the albumen index, Haugh unit, and egg yolk compared to the control group. In contrast, the applied Bacillus species did not affect other egg quality parameter values. The addition of B. megaterium and B. amyloliquefaciens did not significantly influence body weight, heart weight, liver weight, gizzard weight, small intestine length, and cecum length among the slaughter parameters examined. Adding 0.1% (1 × 10⁹ CFU/g), of B. amyloliquefaciens to the laying quail diets can be used without causing a significant difference in performance, egg quality characteristics, and visceral weights compared to the control group.