Hops beta-acids and zinc bacitracin affect the performance and intestinal microbiota of broilers challenged with Eimeria acervulina and Eimeria tenella

摘要

The objective of this study was to evaluate the effects of dietary hops beta-acids on the productive performance and intestinal microbiota of broilers challenged with Eimeria acervulina and Eimeria tenella. 1440 broiler chicks were allocated in a randomized design with 6 treatments and 6 replicates of 40 birds/pen. The treatments were: basal diet, negative control (NC); basal diet supplemented with 30 mg/kg of zinc bacitracin, positive control (PC); NC+ challenge; PC+ challenge; NC+ 30 mg/kg of hop beta-acids + challenge; and NC + 240 mg/kg of hop beta-acids + challenge. At 14 days of age, the birds were challenged with Eimeria acervulina and E. tenella. The performance was evaluated and the analysis of the intestinal microbiota was performed. The coccidiosis infection impaired (P= 0.001) the weight gain, feed intake and the feed conversion ratio in the first week after the challenge. In the second week after the challenge, the effects were less evident. The feed conversion ratio was better (P= 0.05) in the challenged birds, compared to the non-challenged, in the last two weeks of the experiment. Considering the overall experimental period, the weight gain and feed intake were higher in the PC compared to the NC, and among the challenged birds, the feed conversion ratio was better in those receiving zinc bacitracin and hops beta-acids in the diet. Among the challenged birds, the zinc bacitracin and both levels of hops beta-acids decreased (P= 0.009) Clostridiales amount when compared to the unsupplemented birds, in the small intestine at 21 days of age. In addition, the challenge decreased the Staphylococcus (P= 0.01) and Enterococcus (P= 0.001) amounts; however, both additives tended to increase Enterococcus amount (P= 0.09). At 35 days of age, the both levels of beta-acids increased Clostridiales (P = 0.04) and decreased Lactobacillus (P = 0.008) in the small intestine, among the challenged birds. At this age, the challenge tended to increase (P=0.07) Bacteroides amount in the ceca of broilers, and the higher level of hops beta-acids tended to decrease (P=0.09) its amount when compared to the lower level. In conclusion, the hops beta-acids showed similar positive effects to those obtained with zinc bacitracin supplementation on the productive performance changed the intestinal microbiota of challenged birds and have potential to replace the antimicrobial performance enhancers in the diets of broilers. (C) 2015 Elsevier B.V. All rights reserved.