Coccidia Vaccine Challenge and Exogenous Enzyme Supplementation in Broiler Chicken 2-Effect on Apparent Ileal Nutrient and Energy Digestibility and Intestinal Morphology 7 and 14 Days Post-Challenge.

Abstract

The effect of exogenous mixed-enzyme supplementation (xylanase, β-glucanase, and pectinase) and coccidia vaccine challenge (CVC, Coccivac B-52™) on broilers fed a corn-SBM (CS) and a wheat-CS (WCS)-based diet was examined in this study. On day 14, 448 Cobb by-product breeder male broiler chickens were assigned to treatments (factorial arrangement) in a completely randomized design, with each treatment replicated seven times. Treatment effect was evaluated within each diet type as a 2 (enzyme levels) x 2 (CVC, 0 or 20X) factorial arrangement of treatments 7 and 14 days post-CVC. The 7-day (days 14-21) post-CVC, BWG, and feed efficiency (birds on the CS-based diet) were lower (p < 0.05), while birds on enzyme-supplemented diets had higher (p < 0.05) BWG compared to birds on diets without enzyme supplementation. Between days 21 and 28, an interaction between CVC and exogenous enzyme resulted in higher (p < 0.05) BWG compared with the challenged birds fed diets without enzyme supplementation. For birds fed WCS-based diets, CVC influenced (p < 0.05) BWG and feed efficiency (decreased days 14-21 and increased days 21-28), while CVC birds had higher BWG and feed efficiency 14 days post-CVC. Apparent ileal digestibility of dry matter, energy, and DE were lower (p < 0.05) in CVC broilers fed either the CS- or WCS-based diets (7 and 14 days post-CVC). Interaction between CVC and exogenous enzyme supplementation indicated that CVC, irrespective of exogenous enzyme supplementation with the WCS-based diet, decreased (p < 0.05) Ca utilization (7 days post-CVC) but increased (p < 0.05) Ca utilization compared to CVC birds without enzyme supplementation 14 days post-challenge. Seven days post-CVC, irrespective of the diet type, CVC resulted in lower (p < 0.05) duodenal VH and VH:CD and higher (p < 0.05) CD. Enzyme supplementation influenced (p < 0.05) duodenal CD (increased) and VH:CD (decreased) in birds fed the WCS-based diet. Results from this study showed that complete recovery from CVC was influenced by diet type, with CVC birds fed WCS-based diet having higher BWG and feed efficiency compared to the unchallenged birds.