Hulless barley and beta-glucanase levels in the diet affect the performance of coccidiosis-challenged broiler chickens in an age-dependent manner.

ABSTRACT

Diet ß-glucanase (BGase) depolymerizes viscous ß-glucan into lower molecular weight carbohydrates, which might act as a prebiotic in chickens exposed to enteric disease. Coccidiosis-challenged broiler chickens were fed graded levels of hulless barley (HB) and BGase to determine their effects on growth performance. Broilers were fed high ß-glucan HB (CDC Fibar; 0, 30, and 60% replacing wheat) and BGase (Econase GT 200P; 0, 0.01, and 0.1%) in a 3 × 3 factorial arrangement. A total of 5,346 broilers were raised in litter floor pens and vaccinated for coccidiosis in feed and water on day 5. Each treatment was assigned to 1 pen (66 birds) in each of 9 rooms. Statistical significance was set at P ≤ 0.05. Overall, HB decreased body weight gain (BWG) and increased feed gain ratio (FG) of broilers. From day 0 to 11, BGase did not affect BWG and FG, at the 0 and 30% HB. However, at 60% HB, the 0.01% BGase improved them, and the 0.1% BGase had no effect on BWG and increased FG. For the day 22 to 32 and 0 to 32 periods, BGase did not affect BWG for 0 and 30% HB levels, but for the 60% HB, both BGase levels increased gain. The 0.1% level of BGase resulted in the lowest FG for all HB levels, with the degree of response increasing with HB. No interaction was found for ileal digesta viscosity at day 11; the level of HB did not affect viscosity, but both levels of BGase decreased viscosity. At day 33, BGase did not affect viscosity at 0 and 30% HB levels, but viscosity was lowered for the 0.1% BGase treatment at the 60% HB level. In conclusion, HB reduced broiler performance, and BGase alleviated most but not all the effects. In young birds fed 60% HB, 0.1% BGase did not impact BWG and increased FG.