エストロゼンおよびゴイトロゼン投与が反芻動物の第1胃内微生物の数および活性に及ぼす影響

Abstract

The authors wanted to study on the mechanism of the effects of estrogen or/and goitrogen in cattle fattening from the points of digestion physiology.The effects of these two hormonal substances on numbers and activities of rumen micro-organisms were examined in vivo and in vitro. Diethyl-stilbestrol (DES) was used as an estrogen and methylthiouracil (MTU) as a goitrogen.The effects of DES or/and MTU on the numbers of rumen micro-organisms in sheep were examined twice in vivo with different basal rations but no significant effect was found. The effects of these two hormonal substances on ratios of kinds of rumen protozoa in sheep were examined but no significant result was found either. It was found that when the concentrates and alfalfa pellet were given to the sheep, the number of rumen protozoa increased, and the ratio of Entodinium also increased but the one of Diplodinium decreased, comparing with sheep when the concentrates and hay were given.Using artificial rumen, the effects of DES or/and MTU on performance of cellulose digestion of rumen bacteria in cattle were examined in vitro. But no significant effect was found when the concentration of the hormonal substances was the same with the one which had been used ordinarily for cattle fattening. When the concentration of DES in tube of artificial rumen was over 5mcg/ml, the performance of cellulose digestion of rumen bacteria decreased.Using the artificial rumen, the effects of DES or/and MTU on performance of volatile fatty acids production of rumen protozoa in cattle were examined in vitro but no significant effect was found.From the results mentioned above, the authors guessed that the principal mechanism of the actions of hormonal substances in cattle fattening was not in the part of digestion physiology but in the other part, for example, the part of endocrinology.