The histomorphometric changes produced by 'Eimeria' and fishmeal in a broiler necrotic enteritis challenge model

Abstract

Factors predisposing necrotic enteritis in broiler chickens are complex and their respective influences on the morphological changes of gut epithelial layer have not been widely investigated. A 2 x 2 x 2 factorial experiment with or without dietary fishmeal, 'Eimeria' inoculation and 'Clostridium perfringens' challenges was performed with each treatment having six replicates and each replicate containing 25 birds to investigate the influence of these factors on gut morphology. Challenge of the birds by 'C. perfringens' was carried out on d 14 and 15. Duodenal histomorphometrics were conducted using standard paraffin sectioning procedure and the villus height and crypt depth were measured using optical microscopy. The results showed no effects of dietary fishmeal inclusion or 'Eimeria' inoculation or their interaction prior to the 'C. perfringens' challenge, i.e., at d 13. At d 16, 'Eimeria' inoculation significantly reduced villus height (P < 0.001), while 250 g/kg dietary fishmeal significantly increased the crypt depth (P < 0.05). Furthermore, 'Eimeria' inoculation significantly reduced villus height to crypt depth ratio. 'C. perfringens' challenge on d 14 and 15 did not alter the morphometric characteristics. The morphometric data presented herein confirms previous suggestions that 'Eimeria' inoculation is more important than dietary fishmeal inclusion in predisposing birds to necrotic enteritis under experimental conditions.