ルーメン内原生動物の生態学的研究(第III報) : 低級脂肪酸の産生と原生動物の動態
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概要
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The microorganisms of rumen exist in a remarkable symbiosis with the host animal : the rumen provides a suitable environment for the continuous culture of the micoobial population, and the microorganisms produce the nutrient substances essential for the host animal. It is known that the main functions of the rumen microorganisms are to produce the Volatile Fatty Acids (VFA), such as acetate, propionate, butyrate, from the foodstuffs ingested.IIn this paper, some effects of the sdditions of various substrates upon the production of VFA were studied, with special reference to the change of the protozoal population. The apparatus employed in the present experiment inolves the use of the cellophan sac (made in Visking Co. Ltd., ) containing the rumen fiuid obtained from the sheeps fed on hay plus concentrates, which was strained through two layers of cheese cloth immediately after removal. The rumen fluid in the cellophan sac, which is suspended in a water-bath containing the mineral salt solution (Table 1) similar in composition to the rumen fluid and adjusted to pH 6.8,is gassed with CO_2 and the run is conducted at 39℃ for six hours (Fig. 1). Such apparatus could sustain a in vivo microflora, because the sac is simulated in the part which diffusion plays in the activity of the in vivo rumen. This paper records the changes of pH value, the concentration of VFA and the cell density of the protozoa when such substrates as Hydrocellulose, Cellulose powder (powder of filter paper). Starch and Casein are added to the cellophan sac containing the rumen fluid to make the final concentration of 4 per cent. For analysis of the VFA, the column chromatographic method was used. The pH was determined with a glass electrode. The cell number of the Protozoa was counted under the microscope using a mess-slide glass. As the control, the VFA, pH and the cell density of the Protozoa were also estimated on the rumen fluid without any substrate. Table 2 shows that the concentration of total VFA increased following the addition of Hydrocellulose, Cellulose powder, Starch and Casein. Especially, the addition of Starch and Casein accompanied a greater production of the VFA than in the case of adding Hydrocellulose and Cellulose-powder. However, when the data of each component of VFA were converted into percentage of the total acids titrated, similar pictures were given (Fig. 2). It is noticeable that, although different substrates yield different amounts of total VFA, the production-pattern of Vhe components of VFA, acetic acid, propionic acid, butyric acid and the other acids, were nearly the same. The cause of the result remains obscure. The pH maintained nearly a neutral value or slight acidity on adding substrates except Starch, the addition of thich reduced the pH later six hours(Fig. 3). The possibility of a pH effect in vivo was noted earlier by several workers, who observed that the cell density of the Protozoa appeared to be low when the pH value was low and acid concentration was high. In this experiment, the cell density of each Protozoa in six hours after adding Starch were considerably similar to that of the begining, suggesting no damage to the Protozoa due to the decrease in pH and the production of a greater amount of VFA. Similar trends can be noted on adding the substrates except Starch (Fig. 4). Accordingly, it seems that the decrease of protozoal density after feeding in vivo (Fig. 5) depends much more on the dilution with food, water and saliva than on the inhibition of cell division by lowered pH caused by the acid production in the rumen. Besides, the result that the total VFA are significantly low on adding Hydrocellulose and Cellulose powder is likely to be due to the ingestion of Cellulose by Protozoa as well as the slowly fermented nature of Cellulose, because there were seen a fairly large number of Polyplastron swallowing large amounts of Cellulose powder and Hydrocellulose which are seen tightly packed and remain in their
- 日本生態学会の論文
- 1965-04-01