Characterization of water soluble proteins in some forage species and their effects on fermentation process measured by a gas production method

摘要

Five species of forage, including alfalfa hay (Medicago sativa), white clover (Trifolium re-pens), sainfoin (Onobrychis vicifoliq), fodder burnet (Poterium sanguisorba) and maize silage (Zea mays indentata) along with two grass species, Lolium perenneand Glyceria plicata, were used for determination of water soluble protein characteristics. Extractions of forage samples were performed with deionized water under laboratory conditions and the insoluble residues were oven-dried and, together with original samples, used for characterization of ruminal degradation parameters using gas production technique. The water soluble protein was precipitated using acetone or polyethylenglycol, and protein constitution was monitored by polyacrylamide gel electrophoresis. Results showed that the highest amount of soluble protein as a percentage of total protein was found for Lolium perenne, and the lowest percentage was found for clover (P < 0.05). Soluble protein separation was not possible without using sodium dodecyl sulfate (SDS) in gel electrophoresis, and by using SDS different molecular weight proteins were found in the soluble fraction extracted from the forages. The results from the gas production technique showed no significant difference between the two groups of original forage samples or insoluble residue samples (P > 0.05), but within each type of forage, water extraction can both reduce and increase gas production and the increased gas production may be ascribed to removal of anti-nutritional factors with the water-soluble fraction.