Effects of algae derived pure β–Glucan on In vitro rumen fermentation

Abstract

The major purpose of this study was to determine how varying doses of algae-derived pure β–glucan affected in vitro gas generation, volatile fatty acid (VFA) concentrations, methane production, and protozoa populations. Different doses of β–glucan [i.e., 0, 50, 100, 150, and 200 mg/kg feed (DM basis)] were applied to corn silage as experimental treatments. After 6–96 hours of incubation, the dose of 200 mg/kg of DM β–glucan reduced total gas production compared to control (P<0.01). The concentration of total VFA decreased quadratically (P<0.01) as the amount of β–glucan inclusion decreased (except for 200 mg/kg DM) when compared to the control group. The total VFA concentration was found to be the lowest (P<0.01) at 50, 100, and 150 mg/kg DM β–glucan than the other doses. Propionate and butyrate concentrations increased linearly (P<0.01) in the β–glucan supplemented groups, except for the 50 mg/kg DM dosage. When compared to the control group, all doses of β–glucans lowered acetate and the acetate: propionate ratio linearly and quadratically (P<0.01). The addition of β–glucans reduced the number of protozoa linearly (except at the lowest dose) and reduced the methane generation linearly and quadratically (P<0.01). The concentration of NH3-N did not differ (Linear, P=0.12; Quadratic, P=0.19) between treatments. The key findings were that β–glucan acted as a rumen modulator, and levels of more than 50 mg/kg of feed DM functioned as a potential methane regulator in the rumen due to reduced acetate and acetate to propionate ratio.