Efeito acumulativo de dietas com adição de simbiótico sobre a qualidade dos ovos em galinhas de postura até a fase final de produção

Abstract

This study aimed to evaluate the effect of replacing zinc bacitracin with a symbiotic additive composed of a mixture of probiotics (Saccharomyces cerevisiae, Bifidobacterium bifidium, Bacillus subtilis, Entericococcus faecium and Lactobacillus acidophilus) and prebiotics (glucans, mannans) in the diet of laying hens at different rearing stages and egg quality at the end of the laying phase. A total of 198 layers aged 70 to 90 weeks were used, distributed in an entirely randomized design with 6 treatments and 6 repetitions, 3 pens with 6 birds and 3 pens with 5 birds. The treatments were composed of two base diets, the first composed of corn and soybean meal without additives (RMS), the second composed of corn, soybean meal and added meat and bone meal without additives (FCO) and other four test diets based on FCO with additives, one diet with the addition of 0.05% of the additive Zinc Bacitracin (BAC) and the others with the addition of 0.1% of the additive Symbiotic starting in the rearing (SIMBC), breeding (SIMBR) and production (SIMBP) phases. For quality evaluation, the eggs were collected on the last 3 days of the 74th and 90th week of life of the layers. Egg weight (g), yolk (PG), albumen (PA) and shell (PC), percentage (%) of yolk (PCG), albumen (PCA) and shell (PCC), yolk color (CG), shell thickness (EC, mm), albumen height (AB, mm) and Unit Haugh (UH) were evaluated. As the results obtained it was observed that the SIMBC diet results in higher PCA compared to BAC, in the different phases. The increase in PCA was observed when the symbiotic was used starting at rearing. In the 74th week of the birds, a higher PC was observed in the eggs of the BAC diet compared to the FCO and SIMBC diets; a higher PCC was also observed in the eggs of the birds on the BAC diet compared to SIMBC and SIMBR. The birds that received the RMS diet produced eggs with greater EC when compared to the FCO group at both ages evaluated. The SIMBC diet resulted in greater shell thickness compared to the BAC diet, while the SIMBR diet resulted in greater shell thickness at 74 weeks and less at 90 weeks. The CG at 74 weeks in birds fed the RMS or BAC diets produced eggs with better yolk color compared to the FCO diet, and this same effect only occurred in eggs from birds fed the symbiotic in the rearing, growing and production phases. AB and UH had a better maintenance effect on the SIMBR and SIMBP diets. It was found that these results occur due to the strong influence of the symbiotic on the metabolic activity of beneficial bacterial colonies and consequently the better absorption of nutrients by the gastrointestinal tract. Therefore, the use of the symbiotic additive in replacement of the antibiotic is indicated, by improving the quality of eggs from layers in the final phase without losses, especially in the rearing and rearing phases.