Extrato de Macleya cordata na dieta de frangos de corte desafiados por Eimeria spp.

Abstract

The objective of this study was to evaluate the effects of a phytogenic additive extracted from Macleaya cordata in the diets of broiler chickens subjected to a vaccination challenge against Eimeria spp. (a dose 20 times higher than the recommended at 14 days of age), on zootechnical performance, intestinal morphometry, intestinal lesion scores, histopathological changes, intestinal permeability, energy and nutrient digestibility, carcass and cut yields, and immune system parameters. A total of 800 one-day-old male chicks were allotted in a completely randomized design with five treatments and eight replicates. The treatments consisted of a diet without additive and without challenge; a diet without additive and with challenge; and three diets with inclusion levels of the additive (50, 100, and 150 g ton⁻¹ of feed) in challenged birds. At 19 days of age, three birds per replicate were euthanized for measurement of morphometry, lesion score, histopathology, intestinal permeability, determination of serum cytokine and immunoglobulin A levels, and digestibility of digesta. At 42 days of age, two birds per replicate were euthanized for evaluation of carcass and cut yields. Parametric data were subjected to analysis of variance followed by Tukey’s test, and nonparametric data were subjected to the Kruskal-Wallis test followed by Dunn’s test, considering significant differences at P < 0.05. Over the entire experimental period, there were no differences in zootechnical performance (P > 0.05) among the challenged treatments. The nonchallenged birds showed greater (P < 0.05) weight gain compared with the challenged birds that consumed 150 g ton⁻¹ of the additive. For intestinal permeability, non-challenged birds showed lower permeability (P < 0.05), differing from birds that consumed 50 and 100 g ton⁻¹ of the additive. Non-challenged birds had higher digestible protein content (P = 0.0001). For lesion scores in the duodenum, the non-challenged birds and birds from the treatments with 50 and 100 g ton⁻¹ of the additive had lower mean lesion scores (P = 0.0001). In the jejunum, birds receiving 150 g ton⁻¹ of the additive did not present grade-2 lesions (P = 0.0001). In the ileum, birds receiving 100 g ton⁻¹ of the additive showed grade‑3 lesions (P = 0.0001). In the histopathological analysis, non‑challenged birds showed (P < 0.05) lower thickness and less inflammatory infiltration in the lamina propria. Birds that received 150 g ton⁻¹ of the additive showed greater enterocyte proliferation (P = 0.016) compared with birds that received 50 g ton⁻¹, and a lower presence of goblet cells (P = 0.0001) compared with the other treatments. Furthermore, birds that received 50 g ton⁻¹ of the extract in the feed showed greater congestion (P = 0.0001) compared with birds in the negative and positive control treatments. Non‑challenged birds showed a lower total histopathological score compared with challenged birds (P < 0.05). No differences (P > 0.05) were observed for the remaining evaluated parameters. It is concluded that the inclusion of up to 150 g ton⁻¹ of the additive in the diet of broiler chickens subjected to a challenge by Eimeria spp. does not alter performance, intestinal morphometry, or carcass yield. Inclusion of up to 100 g ton⁻¹ of the additive improves lesion scores in the duodenal segment, whereas the dose of 150 g ton⁻¹ of the additive confers an intestinal epithelium that is less susceptible to damage caused by Eimeria spp.