The present study evaluated the effects of coccidiosis on histological parameters and performance of broilers submitted to a mild challenge with Eimeria sp. A total of 132 broilers were randomly divided into two groups with 6 replicates of 11 birds each: negative control (NC) - birds uninfected and challenge (CH) - birds infected by gavage at day-one with 10x the manufacturer recommended dose of Bio-Coccivet R® live vaccine by Biovet, with strains of E. acervulina, E. brunetti, E. maxima, E. necatrix, E. praecox, E. tenella and E. mitis. From 1 to 28 d of age, weekly the zootechnical performance was evaluated and samples of the liver, duodenum, jejunum and ileum were collected and submitted to histological analysis by the I See Inside methodology (ISI). The ISI methodology is a metric evaluation of histological alterations in the intestine and liver. Which translates macroscopic and microscopic alterations into numbers and allows their correlation with the animal zootechnical performance. Pearson's correlation was used to demonstrates how the damages to the gut, evaluated by ISI method, could affect negatively the performance of broilers. The presence of oocysts in histological analysis of the jejunum and ileum at 7d indicate a negative effect on performance over the next 2 weeks (14d and 21d). When the ISI total score was measured in the ileum at 14d, we observed a strong negative effect on zootechnical performance from that period on 14d, 21d and 28d. The obtained data demonstrates that the higher the ISI scores, the worse are the zootechnical performance results of broilers challenged with Eimeria sp. and the I See Inside scores could be applied to evaluate coccidiosis effect on performance in future.
Keywords: Coccidiosis; Histological lesions; Performance; Small intestine.
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