The effect of a β-mannanase-based enzyme on growth performance and humoral immune response of broiler chickens fed diets containing graded levels of whole dates

The use of low-quality whole dates in broilers' diets was evaluated. The apparent metabolizable energy (AMEn) of whole dates and date pits was determined with or without a beta-mannanase-based enzyme (Hemicell - a registered trademark of ChemGen Corp., Gaithersburg, MD. Dried Bacillus lentus fermentation solubles with 158 million units/kg minimum enzyme activity. Recommended usage rate is 0.4 g kg(-1) of feed. ChemGen Corp., Gaithersburg, MD, USA). A 3 x 2 factorial arrangement consisting of whole dates (0, 175, and 350 g kg(-1)) and enzyme (0 or 0.4 g kg(-1)) was performed to assess the effect of the enzyme on the nutritive value of whole dates (experiment 2) in broilers' diet. Enzyme improved AMEn contents of the whole dates and date pits. The diets containing 175 or 350 g kg(-1) whole dates produced body weight gain (BWG) similar to those obtained without dates. Enzyme improved BWG and feed conversion ratio throughout the experimental period. In conclusion, whole dates can be included in broiler diets at levels up to 350 g kg(-1). In addition, beta-mannanase supplementation would have beneficial effects on performance and immunity in birds fed on corn-soy or corn-soy-whole dates diets.