Dietary zinc-methionine and feed restriction affect duodenal morphology of broilers challenged with a mixed coccidial infection

Abstract

The purposes of this study was to investigate effects of additive zinc-methionine (Zn-Met) in a diet contained practical level of Zn and alternate day feeding as physical Feed Restriction (FR) early in life on intestinal morphology after an experimental coccidiosis. Hence, a total of 378 male and female broiler chicks were fed a basal diet (74 mg Zn kg-1) supplemented with 0, 40 or 60 mg Zn kg-1 as Zn-Met which was administrated ad libitum (AL) or with feed restriction. Feed restriction chicks consumed food on alternate days from 11 to 18 day of age. All birds inoculated orally with two species of coccidia on day 28. Duodenal morphology and lesions were scored by microscopic observation on duodenal samples which were taken at day 42 of age. Intestinal lesions were diminished (p<0.01) by dietary supplementation with 40 or 60 mg kg-1 Zn-Met. Also, number of intraepithelial lymphocytes was significantly (p<0.05) increased by 60 mg kg-1 level. But administration of FR could affect neither lesion score nor intraepithelial lymphocyte. The ratio of villus height/crypt depth (V/C) was larger in broiler chicks which received 60 mg kg-1 Zn-Met than unsupplernented group. Birds in FR group had more expanded villus surface (p<0.01) and thinner lamina propria (p<0.001) than AL group. Increase of intraepithelial lymphocytes as an indicator of intestinal immune response and decrease of duodenum lesions in chickens which dietary supplemented with Zn-Met suggest that preparing more available zinc in broilers diet might be necessary to maximize immunocompetence of broilers. Also, alteration of V/C ratio and villus surface area by additive Zn-Met and FR may cause to improve efficiency of nutrients utilization in coccidiosis condition. © 2009 Asian Network for Scientific Information.