Effects of β-mannanase supplementation on growth performance, nutrient digestibility, and nitrogen utilization of Korean native goat (Capra hircus coreanae)

The use of agricultural by-products possessing high β-mannan content as an animal feed ingredient has become increasingly important in achieving cost-effective agriculture. Recent studies showed improvement in growth performance from a diet containing high β-mannan concentrations by the addition of β-mannanase in monogastric animals. Few studies, however, have been conducted to examine the value of β-mannanase supplementation in ruminant diets. In the present study, the effects of β-mannanase supplementation on growth performance, nutrient digestibility, and nitrogen (N) utilization were investigated in growing Korean native goats (Capra hircus coreanae). Twelve Korean native goats (13±1.9 kg) were divided into three groups and randomly allocated into one of the following treatments: (1) control (CON), (2) 0.1% β-mannanase supplementation (TRT1), or (3) 0.3% β-mannanase supplementation (TRT2) in a concentrate mix based on dry matter (DM). Diets composed of 40% of tall fescue hay and 60% of each concentrate mix were formulated to meet the National Research Council requirements for indigenous goats. No difference was observed among treatments in terms of DM intake and highest DM and organic matter digestibility (P<0.05) were observed in goats fed CON. However, β-mannanase supplementation significantly increased the average daily gain (P<0.05) and improved feed conversion ratio (P<0.05) as well as N retention (P<0.05). The N intake (P<0.05) and biological value (P<0.10) increased linearly by increasing the dosage of supplementation of β-mannnase. No difference was observed between the two levels of β-mannanase supplementation. In conclusion, β-mannanase supplementation may promote growth and feed efficiency in ruminant animals receiving feedstuffs with high β-mannan concentrations.