The study, on which four series of abrupt feed change [I. Formula feed→Haycube (alfalfa), II. Haycube→Formula feed, III. Formula feed→Rice straw, and IV. Rice straw→Formula feed+ Haycube(1:1)] was done in order to investigate the role of protozoan microorganisms in the nutrition and the physiology of the sheep rumen.
The number of protozoa in the rumen decreased in each case of abrupt feed change and showed a minimum within 3-5 days. Later the protozoan number increased gradually and attained the typical value of the particular feed in 30-35 days.
The chemical composition in the rumen liquid withdrawn 16 hours after feed supply was comparatively constant despite the large difference of feed composition and abrupt change of the feed throughout the experiment.
The values of carbohydrate, nitrogen, VFA and riboflavin were 220-320 µg, 900-1400 µg, 50-100 µmoles and 0.4-0.6 µg per millilter of the rumen liquid respectively.