The rumen ciliate Ophryoscolex caudatus fermented starch with the production of acetic, butyric, and lactic acids plus CO2 and H2. Cellulose was not significantly metabolized although pectin was rapidly attacked in the Warburg apparatus. The protein sources, cottonseed, soybean, and linseed-oil meals, and the amino acids, DL-alanine, DL-valine, and DL-leucine, were utilized by the protozoan, whereas ammonia was demonstrated as an end product of nitrogenous metabolism. Methods for the separation of 0. caudatus from mixed rumen contents are described.
Insecticides containing organophosphate, chlorinated hydrocarbon, and carbamate were tested with bovine ruminal ingesta fractions. Rumen bacteria exposed to insecticide levels of 0 to 500 ppm in rumen fluid for 4 hr were inoculated into rumen fluid-starch feed extract medium. No apparent significanit bacterial couInt inhibitions were noted. Also, when insecticides were used as carbon sources at concentrations of 500 ppm in carbohydrate-limited media, no increases in bacterial counts were indicated. Warburg manometric data showed that paraffin oil-Triton X-155 preparations of dimethoate, Diazinon, lindane, Thiodan and Sevin stimulated gas production in holotrich protozoa. Entodiniumn simplex, an oligotrich, produced less gas with insecticide substrates per unit of dry weight thani did an Isotricha sp. Rumen bacteria and plant debris fractions from ruminal ingesta provided with insecticides did not give increased manometric responses over the endogenous control vessels. Washed suspensions of I. intestinalis produced volatile fatty acids in excess of the endogenous suspensions when provided insecticide substrates. Thiodan dissimilation by I. intestinalis was followed colorimetrically with 15 % loss in substrate in 1 hr of incubation at 39 C. Diazinon-C14 substrate uptake was demonstrated with suspensions of E. simplex and I. intestinalis. Rumen ciliates are suggested as a possible means for screening out useful insecticides susceptible to microbial dissimilation for use on forage and other cattle-feed crops.
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