CHANGES IN TOTAL AND INDIVIDUAL PROTEINS DURING DRYING, ENSILING, ANDRUMINAL FERMENTATION OF FORAGES

Effects of wilting, drying, and ensiling on concentrations of proteins in alfalfa, crown vetch, perennial ryegrass, orchardgrass, and tall f escue were studied using SDS-PAGE. Seven to nine proteins were identif ied in the samples. Wilting forages for 24 h on a laboratory bench had little effect on the relative amounts of proteins. Drying forage (on a laboratory bench) for 5 d resulted in a 25 to 30% loss in electropho retically identified proteins. A 45-kDa protein was more susceptible t o hydrolysis during drying than were most other proteins. After ensili ng, <10% of the proteins in fresh alfalfa and fescue remained, but cro wn vetch silage contained 46% of its original proteins. A 54-kDa prote in was extremely susceptible to hydrolysis during ensiling, but a 30-k Da protein was relatively resistant. Fresh forage and hay samples were incubated in vitro for 5 h to determine degradation of proteins. In g eneral, the 54-kDa protein was most susceptible, and the 30-kDa protei n was least susceptible, to ruminal hydrolysis. Certain proteins in ha y were more degradable than those in fresh forage. Among fresh forages , alfalfa and fescue contained the lowest concentrations of undegradab le proteins. Differences among forage species were considerably less f or hay samples.