Effects of Abrupt Feed Change on the Rumen Contents

飼料の急変にもとずく飼養条件の変化が,反芻家畜第1胃内に生息する微生物および胃内水溶液の成分組成に及ぼす影響について検討した. 1. プロトゾア数は,同一飼料給与下では一定値を示す傾向があり,配合飼料給与時で160～180万/ml,Haycubeおよび稲わら給与時で50～60万/ml,配合飼料・Haycube混合給与時で220～240万/mlであった.飼料を切り変えることによリプロトゾアは急激し,切り変え後3～5日目に最低値を示し,以後は漸次増加して約1ケ月でその飼料の示す固有数となった. 2. 胃内水溶液中の炭水化物,窒素,VFAおよびリボフラビン含量は,飼料成分の相差および飼料の切り変えにもとづく飼養条件の変化に対して,大きな影響は受けず,比較的一定値を示し,炭水化物220～320μg/ml,窒素900～1400μg/ml,VFA50～100μmoles/mlそしてリボフラビン0.4～0.6μg/mlであった.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 The chemical composition in the rumen liquid withdrawn 16 hours after feed supply was comparatively constant despite the large difference of feed composition and abrupt change of the feed throughout the experiment.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