Effect of Prebiotic Plus Xylanase Enzymes in Reduced-Energy High Wheat Midd Diets on Broilers Subjected to Bursa Vaccine and Clostridium Perfringens Challenge under Heat Stress

Abstract

This study was designed to evaluate the effect of chronic heat stress (CHS) and pathogen challenge on broilers fed reduced energy, high wheat Midd (WM) diets with or without a mixture of yeast cell wall (YCW) and xylanase enzyme (XE) on performance, carcass fat percentage and the evaluation of diet and meat cost. Two hundred forty (1- day old) chicks (Ross 308) were distributed within 2 Petersime battery brooder units (48 pens: 5 birds per pen). For this experiment, treatments were assigned as an incomplete randomized block design with 6 treatments arranged as a factorial 3 × 2 with 3 levels of energy (3000, 2900, and 2800) and 2 treatments with or without supplementing mixture of (YCW 250 ppm plus XE 25/mg per ton) were used. Chronic heat stress CHS was induced by setting the HVAC system at 36± 2ºC from day one until the end of the study (day 24). Birds were vaccinated with a commercial IBD vaccine via eye drop at 10 days of age, followed by Clostridium perfringens challenge on day 16 and 17 of the study by 3/mL oral gavages 106 cfu/ml. Results revealed that the body weight (BW), body weight gain (BW gain), Productivity Index (PI), and feed conversion ratio (FCR) of chicks fed low energy (2800 Kcal with YCW and XE; PVL) then (2900 Kcal with YCW and XE; PL) respectively, were improved numerically but not significantly (P˃0.05) at days 10, 16, 21, and 24 as compared with chicks fed high energy (3000 Kcal with (PC) or without (NC) YCW and XE. Also, no significant differences were found by dual energy X-ray absorptiometry (DEXA scan) among the treated groups, but % fat of birds fed low energy (2800 Kcal plus YCW and XE; PVL) were decreased (P˃0.05) as compared with chicks fed high energy (3000 Kcal with (PC) or without (NC) YCW and XE). However, average cost of the feed and meat were lower of treatment administration diet have 2800, and 2900 Kcal as compared with 3000 Kcal diets. In conclusion, reduced energy diets did not affect under HS may be low energy decrease heat increment. Chicks fed low energy with or without YCW and XE led to enhance performance and lower carcass fatpercentage. In addition, low energy diet led to lower the cost of diets and meat. Keywords: Broiler, performance, reduced energy, heat stress, xylanase, prebiotics.