Effects of energy, α-amylase, and β-xylanase on growth performance of broiler chickens

A study was conducted to evaluate the effects of dietary alpha-amylase and beta-xylanase, in single or combined supplementation, on growth performance of broiler chickens fed maize soy diets. A total of 1800 slow feathering, Cobb x Cobb 500 male broilers were randomly distributed to 8 treatments with 9 replicates of 25 birds each. Broilers were fed starter and finisher diets respectively from 1 to 21 and 22 to 40 d Broilers were fed starter and finisher diets respectively from 1 to 21 and 22 to 40 d. A negative control (NC) diet was formulated to contain 12.35 MJ/kg and 12.85 MJ/kg in the starter and finisher phases, respectively. A further four control diets were formulated with orthogonal energy density increases in increments of 0.21 MJ/kg to a maximum of 13.17 MJ/kg (starter) and 13.67 MJ/kg (finisher). All control diets were formulated to be equivalent in amino acids and minerals. The NC diet was supplemented with alpha-amylase (80 kilo-Novo a-amylase units/kg), beta-xylanase (100 fungal (beta-xylanase units/kg), or both enzymes combined at the same supplementation levels. Increasing AMER resulted in a linear increase (P <0.01) in BWG and a linear decrease (P<0.01) in FCR from 1 to 40 d. Corresponding AMEn estimates for BWG and FCR from 1 to 40 d were, respectively 0.41, 035, and 0.57 and 0.18, 0.11, and 0.21 MJ/kg for amylase, beta-xylanase and amylase + S-xylanase. In conclusion, supplementing maize-soy diets with alpha-amylase and 13-xylanase led to increased estimated energy yields. A marked difference occurred in favor of alpha-amylase when compared to beta-xylanase supplementation whereas adding both enzymes in the same feed generated similar AMEn to the single addition of alpha-amylase. Growth performance responses corresponded to findings in the AMEn assay. (C) 2017 Elsevier B.V. All rights reserved.