Evaluation of β-mannanase and Different Dietary Energy Levels on Egg Production, Apparent Digestibility and Blood Metabolites of Laying Hen

A trial was conducted to investigate the effects of dietary energy levels and β-mannanase supplementation on egg production performance, nutrient retention and blood metabolites of laying hens. Hy-Line Brown layers (n=240, 68 wk-old) were randomly allotted to 6 treatments on the basis of laying performance. Each treatment had 8 replicates with 5 birds. Laying hens were fed three energy levels (2650, 2750 and 2850 kcal/kg) and 0 and 0.4 g β-mannanase/kg diet in a 2×3 factorial arrangement for 56d. Laying hens fed diets supplemented with β-mannanase or high energy (2750 and 2850 kcal) had greater overall egg production. Addition with either high energy diet or β-mannanase improved the egg mass in the second production phase as well as overall egg mass. Feed intake was decreased in laying hens fed the highest (2850 kcal) dietary energy level. Moreover, laying hens fed the highest energy diets had a greater feed conversion ratio. Laying hens fed diets with β-mannanase had greater retention of DM, GE and CP than hens fed diets without β-mannanase. Retention of mannose was greater in laying hens fed diets supplemented with β-mannanase or high energy diets. The results obtained indicate that a high energy content in diets had positive effect on the performance of laying hens and that dietary supplementation with β-mannanase has the potential to improve laying hen performance and nutrient retention.