An evaluation of endo-β-D-mannanase (Hemicell) effects on broiler performance and energy use in diets varying in β-mannan content

Abstract

Two experiments were conducted to evaluate the effects of a commercial endo-β-D-mannanase (Hemicell) on overall performance, MEn, net energy for gain, and some serum parameters of broilers fed diets varying in β-mannan level (experiment 1) and to evaluate effects of enzyme level on the same variables in broilers fed diet high in β-mannan (experiment 2). As a semipurified β-mannan source, guar gum was used to alter the dietary β-mannan level. In experiment 1, guar gum was added at 0, 0.5, 1, and 2% in a corn-soy-based starter diet with (0.05%) and without endo-β-D-mannanase supplementation in a 4 × 2 factorial design. Enzyme supplementation improved (P < 0.01) feed efficiency at control and each guar gum inclusion level, whereas 2% guar gum supplementation reduced (P < 0.01) BW and increased (P < 0.01) 14-d feed:gain ratio. Enzyme supplementation also increased dietary MEn and net energy gain. In experiment 2, endo-β-D-mannanase was added at 0, 0.5, 1, and 1.5% in a corn-soy-based starter diet containing 1% guar gum. Increasing endo-β-D-mannanase supplementation did not affect (P > 0.10) final BW but improved 14-d feed:gain ratio at all inclusion levels. As in the first experiment, ME improved (P < 0.05) with increasing enzyme inclusion. Dietary endo-β-D-mannanase inclusion significantly reduced water:feed ratio and total dry fecal output (P < 0.01). Taken together, the results of these 2 experiments indicate that endo-β-D-mannanase supplementation may improve the utilization of nutrients in diets containing β-mannan.