Reticulo-omasal Orifice Research Articles

The formation of volatile fatty acids in the rumen contents of cows in vivo and in vitro

On a diet containing fodder sugar beets the proportion of butyric acid in the mixture of the volatile fatty acids of the rumen contents was found to be unusually high. When the rumen contents were incubated at different pH-levels in vitro, it was found that the proportion of butyric acid in the volatile fatty acid mixture produced increases when the pH decreases. Using polyethylene glycol as a reference substance, the transfer of fluid through the reticulo-omasal orifice was studied. The transfer of volatile fatty acids into the omasum is calculated on the basis of the fluid flow and on the acid concentrations of the fluid in the lower anterior part of the contents.

Paper as a Carrier of Chromium Sesquioxide

CHROMIUM sesquioxide (Cr2O3) is widely used for estimating feed digestibility1 or faeces output2 by ruminants, but such estimates may be subject to considerable errors because the concentration of this marker in faeces normally shows considerable diurnal variations even after prolonged regular administration. These variations are particularly obtrusive with grazing animals where the chromium sesquioxide, in this case used for estimating the output of faeces, is usually administered in concentrated powder form in gelatin capsules once or twice daily, and they probably arise primarily from an imperfect mixing of the oxide with digesta in the reticulo-rumen3,4. This view is supported by unpublished observations (by J. F. D. Greenhalgh) on the concentrations of chromium sesquioxide in the organic matter of digesta obtained from the duodenum of a sheep permanently cannulated at this point. As the variations in concentration during a period of regular dosing showed the same pattern and were greater than those found in the faeces, it was decided to study in a comparably cannulated sheep the passage of single doses of oxide powder, each given in a gelatin capsule and in amount large enough to give measurable concentrations over a considerable period of time. Samples of digesta were drawn from the duodenum at intervals beginning 1 hr. after dosing. Results from a typical run where 8 gm. were given are shown in Fig. 1 (line A) and indicate that a large part of the dose had passed from the stomachs within 4 hr. of administration. The probable explanation is that the capsule container dissolved quickly in the anterior rumen or reticulum3 and that local concentrations of chromium sesquioxide in these regions4 were rapidly transferred through the reticulo-omasal orifice.