ABSTRACT
The objective of this study was to evaluate the effect of adding symbiotics to the diet of laying hens in the post-peak laying period on performance variables, egg quality, and nutrient digestibility. One hundred and ninety-eight 70-week-old Dekalb White laying hens were distributed in a completely randomized design with 6 treatments, each with 6 replications of 5 and 6 birds. The treatments were: corn and soybean meal (CSM); CSM + meat and bone meal (MBM); MBM + 0.05% zinc bacitracin additive (ZnBac); MBM + 0.1% Symbiotics in three phases: layer-type chick, pullet, and laying hen (Symb-S; Symb-G and Symb-L). Data were compared by Orthogonal Contrast. The CSM treatment showed better shell thickness when compared to MBM, and a better percentage of albumen. RF and BacZn showed better yolk coloration. ZnBac showed better yolk weight when compared to Symb-S. CSM and ZnBac increased red and yellow yolk colors and Symb-G had an effect for luminosity. The gross energy apparent metabolizability coefficient (GEAMC) was better for CSM and Simb-G. The crude protein apparent metabolizability coefficient (CPAMC) was better with MBM. The dry matter apparent metabolizability coefficient (DMAMC) was better for MBM, Symb-S, and Symb-L. Thus, it is possible to replace antibiotics with symbiotics for laying hens in the post-peak phase.
Keywords:
Additives; growth promoters; nutrient digestibility; prebiotics; probiotics
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