Study of the influence of exogenous fibrolytic enzyme additive on chemical composition, fermentation characteristics, and nutritional value of brewer's spent grain

Abstract

This study explores the influence of different doses of two exogenous fibrolytic enzyme (EFE) additives (liquid (EFE₁: 1, 2, and 4 μΙ/g DM (dry matter)) and powder (EFE₂: 1, 2, and 4 mg/g DM)) on the chemical composition, fermentation characteristics, and nutritional value of brewer's spent grain (BSG). The results indicate that EFE₁ at low doses does not affect the chemical composition, fermentation characteristics, and the nutritional value of BSG. The medium dose EFE₁ decreases the fiber compound but increases the nonfiber carbohydrates (NFC) and soluble dry matter. Also, this dose modified the fermentation of BSG by increasing the amount of gas and its fermentation rate and decreasing the time between the inoculation and start of fermentation. Therefore, it increases the digestibility, metabolizable energy, net energy-lactation (NE_L), total volatile fatty acids, and the microbial crude protein production of BSG. The high dose of EFE₁ decreases the fiber compound and increases the nonfiber carbohydrates and soluble dry matter; however, it also decreases the potential of gas production and does not affect the nutritional value of BSG. For EFE₂, all the doses do not modify the chemical composition, fermentation characteristics, and the nutritional value of BSG. These results suggest that the effectiveness of EFE varied, depending on the type of EFE and dose. Increase in the nutritional value of BSG by EFE₁ at the medium dose can encourage breeders to use these wastes as feed at low cost in cow nutrition.

Keywords: Brewer's spent grain; chemical composition; exogenous fibrolytic enzyme; fermentation characteristics; nutritional value.