Effect of the Probiotic Bifidobacterium animalis as a Substitute to Growth-Promoting Antibiotics on Performance and Egg Quality in Laying Hens.

The present study was conducted to determine the effects of a dietary probiotic (Bifidobacterium animalis ssp.) as a substitute to a mixture of growth-promoting antibiotics (zinc bacitracin and colistin sulfate on the laying performance, egg quality characteristics, blood parameters, and organ morphological characteristics of early-phase laying hens. Seventy-two (72) 20-week-old Lohmann White hens were randomized into three treatment groups. The dietary treatments are as follows: Growth-promoting antibiotics (GPA; 0.5 % of COLI-ZIN), probiotic (PRO; 0.1% Bifidobacterium animalis ssp. lactis) or without any additive (control; CON) for 90-days feeding trial. Significant differences were observed in feed intake and feed conversion ratio of the bird's fed PRO compared to GPA and CON at 90 days of the experimental period. The air cell height, yolk volume, and yellowness of yolk color were lower, and thick and thin albumen diameters were the greatest in the PRO group than in CON and GPA groups (P<0.05). Dietary PRO decreased the number of heterophils (H) and increased the number of lymphocytes (L), improving the H:L index (P<0.05). Probiotic treatment increased crop and duodenum relative weight compared to GPA (P<0.05). No significant changes (P>0.05) were observed in the relative weight of reproductive organs. This study shows that the dietary supplementation of 0.1% Bifidobacterium animalis improves laying performance and egg traits and can be a substitute for antibiotics in hen diets. [ABSTRACT FROM AUTHOR]