Effects of β-mannanase on nutrient utilization and performance of laying Chicken

The study was done at the Department of Animal Science, University of Manitoba. Two experiments were conducted to investigate the effects of β-mannanase on nutrient utilization and performance of laying hens. Experimental diets were based on soybean meal (SBM), corn and distillers dried grains with solubles (DDGS). The first study was designed to evaluate the effect of β-mannanase (CTCZYME, CTC Bio Inc., Seoul, South Korea) on performance of laying hens and egg quality traits. A total of 160 Lohmann hens were allocated to one of 4 diet groups in 2 levels of dietary protein plus energy content [18.5% crude protein with 2,850 kcal/kg metabolizable energy (ME) (Adequate-ME&CP) vs. 17.5% crude protein with 2,700 kcal/kg ME (Low-ME&CP)]. β-mannanase was added at 0 and 0.04% of diet to both diet types. The experiment lasted for 12 weeks and was designed in a 2 × 2 factorial arrangement. Each group had 8 replicates of 5 hens. Eggs were collected daily and egg production was calculated on a hen-day basis. Egg weight, albumen height, egg specific gravity, eggshell breakage and egg shell thickness were measured bi-weekly and Haugh Units was calculated from the egg weight and albumen height. Feed intake was recorded weekly and calculated as g/hen/day. There were no significant differences in overall egg production and feed efficiency among birds fed on the 4 dietary treatments for the 12-week period. However, average feed conversion ratio (FCR) from the second to the last month of hens fed the low-ME&CP diet was higher than that of hens fed the adequate-ME&CP diet irrespective of enzyme supplementation. Feeding the low-ME&CP diet significantly increased (P0.05) egg shell strength, egg specific gravity and Haugh Units. A significant viii interaction (P