Rumen fluid fermentation for enhancement of hydrolysis and acidification of grass clipping

Rumen fluid, formed in rumen of ruminants, includes a complex microbial population of bacteria, protozoa, fungi and archaea, and has high ability to degrade lignocellulosic biomass. In this study, rumen fluid was used to ferment grass clipping for enhancing the hydrolysis and acidification of organic matters. Results showed that strict anaerobic condition, higher grass clipping content and smaller particle size of grass clipping were beneficial to the hydrolysis and acidification of organics. The increase of SCOD and total VFA concentration respectively reached 24.9 and 10.2 g/L with a suitable grass clipping content of 5%, a particle size < 0.150 mm, and a fermentation time of 48 h. The VFA production was mainly attributed to the degradation of cellulose and hemicellulose with a total solid reduction of 55.7%. Firmicutes and Fibrobacteres were the major contributors to the degradation of cellulose and hemicellulose. The activity of carboxymethyl cellulose enzyme (CMCase), cellobiase and xylanase reached 0.027, 0.176 and 0.180 U/ml, respectively. The rumen fluid microorganisms successfully enhanced the hydrolysis and acidification of grass clipping.