CHARACTERIZATION OF IN-SITU DEGRADATION OF LUCERNE PROTEINS ACCORDINGTO FORAGE TYPE (GREEN FORAGE, HAY AND SILAGE) USING GEL-ELECTROPHORESIS

We compared the degradation of lucerne proteins in the rumen according to forage type (green forage, hay, silage) and to plant organ (stems and leaves). Four ruminally fistulated sheep were used. They were fed the same forage as that placed in the nylon bags. Forages were incubat ed in nylon bags at eight different times (0-48 h) in the rumen. Prote ins were extracted, and separated by sodium dodecylsulphate-polyacryla mide gel electrophoresis. The theoretical nitrogen degradabilities (De g) were similar between forages (83.5 for hay to 89.3 for silage treat ed with formic acid). The main forage protein, ribulose 1-5-diphosphat e carboxylase (rubisco), was degraded rapidly in the rumen for fresh f orage and hay. Little rubisco was found in stems and degradation appar ently was already complete in the silo for silages. Proteins of chloro plast membranes resisted breakdown during early fermentation and compl etely disappeared at 48 h for all the forages.