Growth performance, nutrient utilization, and digesta characteristics in broiler chickens fed corn or wheat diets without or with supplemental xylanase

Efficacy of supplemental xylanase on growth performance, nutrient utilization, and digesta characteristics in broiler chickens fed corn- or wheat-based diets was investigated. In experiment 1, 192 male broilers (8 birds/pen; n = 6) were fed 4 diets (corn or wheat without or with 1,250 xylanase units/kg) in 2 phases (starter, d 0–21 and grower, d 22–42). There was no interaction (P > 0.05) between diet and xylanase on performance (d 0–42). Wheat diets resulted (P < 0.01) in better performance than corn diets, whereas xylanase-fed birds had improved (P < 0.01) BW gain (2,457 vs. 2,275 g) and feed per gain (1.677 vs. 1.762) relative to birds not fed xylanase. In experiment 2, TiO₂ (0.3%) was added in starter diets used in experiment 1, allocated to 13-d-old broiler chicks (n = 6) housed in cages (6 birds/cage) and fed up to d 21. Excreta samples were obtained from d 17 to 20 and birds were euthanized on d 21 for digesta. Corn diets had a greater concentration (10.7 vs. 9.8%) of insoluble nonstarch polysaccharides (NSP) than wheat diets, which in turn had more than twice the concentration of soluble NSP. There was an interaction (P < 0.03) between diet type and xylanase on jejunal digesta viscosity but not (P > 0.10) on apparent ileal digestibilities of nutrients, cecal volatile fatty acids, and AMEₙ. In this context, diet type influenced (P < 0.05) cecal volatile fatty acids and retention of nutrients and fiber but did not affect (P = 0.45) AMEₙ. In contrast, xylanase-fed birds showed higher (P < 0.05) ceca digesta acetic acid, apparent ileal digestibilities of nutrients, and retention of components. As a result, birds fed xylanase had higher AMEₙ (3,059 vs. 2,995 kcal/kg; P < 0.01) compared with birds not fed xylanase. Although wheat diets had superior growth performance, the AMEₙ was similar in both diets. Xylanase improved growth performance and AMEₙ independent of diet type, suggesting hydrolysis of both soluble and insoluble NSP.