Effect of β-mannanase supplementation in low-energy and lowprotein diets on performance, intestinal morphology, and fatty liver incidence in laying hens

Objective: This study aimed to investigate the effect of dietary β-mannanase supplementation in low-energy and low-protein diets containing palm kernel meal and copra meal on productive performance, egg quality, intestinal morphology, and fatty liver incidence in laying hens.Methods: A total of four hundred 26-wk-old Hy-Line Brown laying hens were allotted to 1 of 5 dietary treatments with 8 replicates. The positive control (PC) diet was prepared with corn and soybean meal, whereas the negative control (NC) diet was formulated with decreased AMEn by 100 kcal/kg and CP by 0.85% than PC diets. High-mannan NC diet was also prepared by inclusion of 2.5% palm kernel meal and 2.5% copra meal, which was designed to contain energy and nutrient concentrations equal to those in the NC diet. Finally, dietary β-mannanase was supplemented to the high-mannan NC diet at the levels of 0.05% and 0.10%.Results: Most productive performance and egg quality were not affected by dietary treatments. For jejunal morphology, villus height:crypt depth (VH:CD) ratio for hens fed PC diets or NC diets was greater (p