Anaerobic ensiling of raw agricultural waste with a fibrolytic enzyme cocktail as a cleaner and sustainable biological product

Abstract

The increasing expansion of agricultural activities have resulted in an unending production of agricultural waste which constitutes environmental nuisance, if not properly disposed. In most developing countries, this waste is burnt causing environmental problems and health challenges. The utilization of biodegraded ensiled agricultural waste, as an energy source, in livestock nutrition is proposed as a viable solution of reducing pollution. Agricultural waste such as straws is carbohydrate-rich materials that have a large potential as a dietary energy source for ruminants. This study aimed to determine the effect of anaerobic ensiling of raw agricultural waste with a fibrolytic enzyme cocktail as a cleaner and sustainable biological product for animal feed. Ten samples of 1 kg each of wheat straw, corn stalks and sugarcane bagasse were ensiled with enzyme cocktail at 0, 1 or 3 mL/kg dry matter of feed. Before ensiling, feed samples were chopped at 5 cm and moistened to a relative humidity of approximately 50% and then kept for 30 d in plastic bales. Feed type × enzyme level interactions were observed (P < 0.01) for nutrient contents and fermentation kinetics. Increasing the level of enzyme cocktail increased (P < 0.01) crude protein and ether extract contents but decreased organic matter and non-structural carbohydrates contents of the three feeds. The enzyme cocktail also decreased (P < 0.01) neutral detergent fiber, acid detergent fiber, cellulose and hemicellulose contents of corn stalks and sugarcane bagasse. The high level of the enzyme cocktail increased (P < 0.05) methane production from corn stalks but decreased it from sugarcane bagasse. Fermentation parameters response to ensiling differed among the ensiled feeds. It can be concluded that anaerobic fermentation of enzyme-treated agricultural waste and feeding it to livestock is one of the viable ways of utilizing this waste which otherwise could have constituted nuisance and pollution to the environment, if incinerated or improperly disposed.