Evaluation of Fungal Cellulases in Rice Hull Base Diets for Ruminants

Abstract

Ground rice hulls were treated with a preparation of fungal cellulolytic enzymes having a specific gravity of 1.4 kg/liter at 0, 125, 250, 375, 500, 625, 750, 875, 1000, 1125, and 1250mg enzyme preparation per kilogram. In vitro dry matter digestibility (30.6%) was highest when 375mg enzyme preparation were added to 1kg rice hulls. The preparation of fungal cellulolytic enzymes was added to a diet with 50% ground rice hull base at 0, 250, 375, 500, 750, 1000, and 2000mg of enzyme preparation per kilogram. Six Holstein steers, averaging 132kg body weight, were used per treatment in digestion trials with total fecal collection to determine the apparently digestible dry matter, energy, and protein of diets treated with the preparation of fungal cellulolytic enzymes. Diets treated with 250, 375, 1000, and 2000mg of enzyme preparation per kilogram had higher digestibilities of dry matter and energy than those diets treated with other amounts of the fungal cellulolytic enzyme preparation. Protein digestibility was greater when 250, 500, or 2000mg of the fungal cellulolytic enzyme preparation were added to the diet. Thus, the addition of a preparation of fungal cellulolytic enzymes added in small amounts (250mg of enzyme preparation per kilogram diet) enhanced digestibilities of dry matter, energy, and protein of a 50% rice hull base diet.