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 r3-glucan affected in vitro gas generation, volatile fatty acid (VFA) concentrations, methane production, and protozoa populations. Different doses of r3-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 r3-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 r3-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 r3-glucan than the other doses. Propionate and butyrate concentrations increased linearly (P<0.01) in the r3-glucan supplemented groups, except for the 50 mg/kg DM dosage. When compared to the control group, all doses of r3-glucans lowered acetate and the acetate: propionate ratio linearly and quadratically (P<0.01). The addition of r3-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 r3-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.