Efeito continuado de simbiótico em dietas para poedeiras da fase de cria à produção

Abstract

The objective of this work was to evaluate the effect of symbiotic supplementation in diets for laying hens at peak laying compared to the use of zinc bacitracin antibiotic on productive performance, egg quality, hematology and serum biochemistry, nutrient digestibility and intestinal histomorphology. A total of 384 Dekalb White laying hens, aged 1 to 45 weeks, were distributed in a completely randomized design, in 6 treatments, containing 8 replications of 8 laying hens each. The treatments consisted of a diet composed of corn and soybean meal and without additives (RR); a diet composed of corn, soybean meal and meat and bone meal without additives (FCO); an FCO diet supplemented with 0.05% Zinc Bacitracin (BacZn); and, a FCO diet supplemented with 0.1% of symbiotic additive with consumption starting in the rearing, rearing and laying phases, originating the Simb-C treatment (diet with symbiotic since the first day of life; the Simb-R treatment ( diet from the rearing phase); and, the Simb-P treatment (diet containing symbiotic in the laying phase. From the 26th to the 45th week, data on productive performance and egg quality were collected. excreta collections in order to evaluate the digestibility of nutrients; Blood samples were collected at the 44th week of age for the evaluation of hematology parameters and serum biochemistry and, at the end of the 45th week of life, organs were weighed and portions of the duodenum and jejunum in order to evaluate the histomorphology of the tissues. The averages of the results obtained were compared by orthogonal contrasts (P≤0.05), being RR x FCO, FCO x BacZn, BacZn x Simb-C, BacZn x Simb-R and BacZn x Simb-P Regarding the productive performance, the Simb-R treatment provided higher egg mass and feed conversion when compared to the BacZn treatment; Data regarding the quality and composition of the eggs state that the treatments corresponding to the inclusion of the symbiotic provided eggs with a lower percentage of yolk and a higher percentage of albumen when contrasted with the antibiotic, regardless of the time of use. Analyzing the nutrient digestibility data and intestinal morphology, the symbiotic additive obtained lower results for CMAMS, CMAPB, CMAEB, EMA and EMAn when compared to zinc bacitracin; while it provided better characteristics (villus height, crypt depth, villus:crypt ratio and villus area) to the intestinal epithelium of laying hens regardless of the inclusion phase. Therefore, it is concluded that the symbiotic additive provides good productive performance, especially when used in the rearing phase; ensures the production of eggs with good quality and composition; maintains the integrity of the intestinal epithelium and provides good histomorphological characteristics regardless of the time of use. It is a potential substitute for Zinc Bacitracin, ensuring healthy laying hens and good animal performance.