Distribution of radiomanganese in the rumen of XXXX .

@entity292 @entity2804 @entity742 @entity921
Twelve @entity742 , each prepared with a rumen @entity292 , were divided into three groups of four and fed three dietary levels of @entity921 (22,300, and 3000 micrograms/g dry matter) for 11 weeks. The @entity742 were then dosed with radioactive @entity921 and samples of rumen contents were taken via the rumen @entity292 at 1, 7, and 13 h after dosing. The @entity742 were immediately killed after the last sampling and total rumen contents were mixed and sampled. Rumen fluid was separated frm all samples and fractionated by centrifugation into protozoa plus plant particles, bacteria, and cell-free fraction. The bacterial cells were disrupted and fractionated into cell walls and cytoplasm. The cytoplasmic protein was precipitated with @entity2804 . Although the centration of radiomanganese in rumen fluid decreased with time after dosing from 14.4--17.8 to 6.1--9.3% of dose/L the protozoal and bacterial uptakes of radiomanganese were not significantly different and ranged from 26.5 to 40.6% and 18.9 to 31.7% of total in the rumen fluid, respectively. There was also no effect of dietary concentration of @entity921 on the uptake and distribution of radiomanganese in the rumen fluid fractions. However, on the average more radiomanganese was found in the bacterial cell walls (48.1--75.3% of total in bacteria) and less in the cytoplasm (51.9--24.7% of total in bacteria) with increasing dietary @entity921 . Very little radioactivity was found in the @entity2804 precipitated cytoplasm (1.79--0.78% of total in cytoplasm). concentrations of @entity921 in the bacteria and bacterial cell walls were higher than, and closely related with, those in the diet. Specific activities of radiomanganese decreased in all fractions with increasing dietary @entity921 . Approximately 15--17% of the total radiomanganese in the rumen contents at 13 h after dosing was found in the protozoal fraction and 10--15% was found in the bacterial fraction; only approximately 21% of the radiomanganese remained in cell-free fraction of the rumen fluid in each dietary treatment.
