Effects of exogenous β-glucanase on ileal digesta soluble β-glucan molecular weight, digestive tract characteristics, and performance of coccidiosis challenged broiler chickens fed hulless barley-based diets with and without medication

Abstract

Limited use of medication in poultry feed led to the investigation of exogenous enzymes as antibiotic alternatives for controlling enteric disease. The objective of this study was to evaluate the effects of diet {beta}-glucanase (BGase) and medication on {beta}-glucan depolymerization, digestive tract characteristics, and performance of broilers. Broilers were fed hulless barley (HB) based diets with BGase (Econase GT 200P from AB Vista; 0 and 0.1%) and medication (Bacitracin and Salinomycin Na; with and without) arranged as a 2 x 2 factorial. In Experiment 1, 160 broilers were housed in cages from d 0 to 28. Each treatment was assigned to 10 cages. In Experiment 2, broilers (2376) were housed in floor pens and challenged with a coccidiosis vaccine on d 5. Each treatment was assigned to one floor pen in each of nine rooms. In Experiment 1, the soluble {beta}-glucan weight average molecular weight (Mw) in the ileal digesta was lower with medication in the 0% BGase treatments. Peak molecular weight (Mp) and Mw were lower with BGase regardless of medication. The maximum molecular weight for the smallest 10% {beta}-glucan (MW-10%) was lower with BGase. In Experiment 2, Mp was lower with medication in 0% BGase treatments. Beta-glucanase resulted in lower Mp regardless of medication, and the degree of response was lower with medication. The MW-10% was lower with BGase despite antibiotic addition. Body weight gain (BWG) and feed efficiency were higher with medication regardless of BGase use through-out the trial (except d 11-22 feed efficiency). Beta-glucanase resulted in higher BWG after d 11, and lower and higher feed efficiency before and after d 11, respectively, in unmedicated treatments. In conclusion, BGase and medication caused the depolymerization of soluble ileal {beta}-glucan. Beta-glucanase appeared as a partial replacement for diet medication to increase coccidiosis challenged broiler performance.