Aditivo simbiótico em dietas para aves poedeiras na fase de cria

Abstract

The study evaluated the effects of supplementation of symbiotic based on Saccharomyces cerevisiae, Bifidobacterium bifidum, Bacillus subtilis, Enterococcus faecium, Lactobacillus acidophilus, Glucans and Mannans in the feed of laying hens in the rearing phase as a replacement for the antibiotic zinc bacitracin. A total of 1040 chicks of the Dekalb White strain, 1 to 5 weeks of age, were used, distributed in DIC with 4 treatments and 10 repetitions of 26 birds. The treatments were composed of two base diets: the first composed of corn and soybean meal (RR); the second, identical to the first, with added meat and bone meal (MBM); and two other MBM-based diets, one with added 0.05% of the additive zinc bacitracin (Bac Zn), and the other with added 0.1% of the symbiotic additive (Simb-C). Performance, hematology, serum biochemistry, the weight of the immune system organs (thymus, spleen and bursa of fabricius), digestive (liver, pancreas and intestine) and length measurement (intestine and cecum) was evaluated. Variables were analyzed by the SAS program and means were compared using the Orthogonal contrast test (P≤0.05). The contrasts consisted of C1: RR vs FCO; C2: FCO vs Bac Zn; and C3: Bac Zn vs Simb-C. From 14 to 35 days of age, birds fed the RR diet had lower performance compared to FCO, similarly FCO was lower compared to the Bac Zn diet. From 1–14 and 1–21 days of age, the performance of birds fed the symbiotic were higher than that of birds supplemented with bacitracin, and both were equal for 28 days until the end of the phase. An effect was observed in the RR vs FCO contrasts for liver weight and cecum length, and in the Bac Zn vs Simb-C contrasts for liver and bursa weight. Chicks fed RR had higher liver weight and increased cecal length. Chicks fed Simb-C had lower liver and bursa weights. The serum biochemistry variables presented statistical difference for alkaline phosphatase and glutamyl transferase for all comparisons, where RR presented higher values of both variables compared to FCO, when additives were added to the diets, the values of these variables decreased considerably, in which the Bac Zn group presented lower value for phosphatase, and the Simb-C group presented lower value for glutamyl. For creatinine, the birds in the RR group showed the lowest value compared to the FCO, and the FCO group had the lowest value compared to Bac Zn. The Bac Zn diet showed a higher value for globulin and lower value for urea compared to Simb-C. These results reflect the beneficial modulation of microbiota by using growth-promoting additives. Through the results obtained, the symbiotic showed itself as a possible substitute for zinc Bacitracin, without depreciating the performance of the birds in the rearing phase.