Effect of endo-1,4-beta-xylanase supplementation to low-energy diets on performance, blood constituents, nutrient digestibility, and gene expressions related growth of broiler chickens.

The presence of soluble and insoluble non-starch polysaccharides (NSP) was reported to reduce nutrient utilisation, and adversely impact the broilers' growth performance; accordingly, NSP-degrading enzymes are essential supplements to cereal-based diets. Therefore, the current trial was conducted to characterise the impacts of supplemental xylanase (Xyl) to diets with low-ME levels on performance, carcass traits, blood parameters, nutrient digestibility and some genes expressions in broiler chickens. A total of 600 1-day-old Ross 308 male broiler chicks were randomly assigned to 6 treatments with 10 replications of 10 birds each per group in a completely randomised design. The 6 treatments were as follow: (1) basal diets with balanced ME content served as control (positive control, PC), (2) low-energy diet (negative control 1 [NC1]; ME content reduced by 70 kcal/kg compared with PC), (3) low-energy diet (negative control 2 [NC2]; ME content reduced by 140 kcal/kg compared with PC), (4) NC1 + 100 g/ton xylanase (NC1 + 100Xyl), (5) NC2 + 100 g/ton xylanase (NC2 + 100Xyl), and (6) NC1 + 50 g/ton xylanase (NC1 + 50Xyl). At the end of the experiment (35 days of age), the reduction of energy in the NC diets yielded lower live body weight (BW) and total body weight gain (BWG) (p ˂ 0.001); however, it significantly increased feed intake (p ˂ 0.05), leading to worst feed conversion ratio (FCR) and European production efficiency factor (EPEF) (p ˂ 0.01) than PC. There was non-significant variation in final BW, BWG, FCR, or EPEF between the PC group and the NC groups supplemented with Xyl. Carcass yield, gizzard, liver and, muscle relative weights were not influenced by dietary treatments; while broilers fed diet with low-energy diets with or without Xyl addition had lower abdominal fat (p ˂ 0.01) than PC. Furthermore, broilers fed on low-ME diets supplemented with Xyl showed a reduction in plasma total cholesterol (p ˂ 0.05) and low density lipoprotein (p ˂ 0.01) levels. Greater antibody titre against Newcastle disease (p ˂ 0.05) was recorded in the NC1 + 100Xyl and NC2 + 100Xyl groups. The addition of Xyl to low-energy diets significantly improved (p ˂ 0.05) fibre digestibility compared to the PC group. Moreover, enzyme supplementation increased muscle total lipids content and decreased muscle thiobarbituric acid retroactive substance content. In addition, enzyme supplementation increased gene expression related to growth and gene expression related to fatty acid synthesis. It was concluded that a low-ME diet might diminish broiler performance, whereas Xyl supplementation to low-ME diets beneficially affected growth performance, abdominal fat percentage, nutrient digestibility and immunity for broilers, and gene expressions related to growth and fatty acid synthesis in broiler chickens fed low-energy diets.

Effects of Dietary Xylanase and Arabinofuranosidase Combination on the Growth Performance, Lipid Peroxidation, Blood Constituents, and Immune Response of Broilers Fed Low-Energy Diets.

The present study was conducted to examine that impact of dietary xylanase (Xyl) and arabinofuranosidase (Abf) supplementation on the performance, protein and fat digestibility, the lipid peroxidation, the plasma biochemical traits, and the immune response of broilers. A total of 480, un-sexed, and one-day-old broilers (Ross 308) were randomly divided into three treatments with eight replicates, where chicks in the first treatment were fed basal diets and served as the control, chicks in the second treatment were fed diets formulated with reductions of 90 kcal/kg, and chicks in the third treatment were fed the same formulated diets used in the second group as well as the Xyl and Abf combination (Rovabio® Advance). Feed intake was decreased by the low energy diet, leading to an enhancement in feed efficiency enzyme supplementation in the low energy diet (p < 0.015). Both protein and fat digestibility were improved (p < 0.047) due to enzyme supplementation. Moreover, enzyme supplementation increased muscle total lipids content and decreased muscle thiobarbituric acid retroactive substance content. Furthermore, diets supplemented with Xyl and Abf exhibited an increase in antibody titers against the Newcastle disease virus (p < 0.026). In addition, enzyme supplementation increased gene expression related to growth and gene expression related to fatty acid synthesis. It could be concluded that dietary Xyl and Abf supplementation had beneficial impacts on growth, nutrient digestibility, lipid peroxidation, immune response, and gene expressions related to growth and fatty acid synthesis in broiler chickens fed low-energy diets.