Passage of protozoa and volatile fatty acids from the rumen of the sheep and from a continuous in vitro fermentation system

Abstract

1. A procedure for sampling digesta from within the omasal canal of sheep given a variety of roughage diets was used to enable comparison to be made of the composition of effluent from the reticulo-rumen with that of rumen fluid.2. Concentrations of protozoa in effluents, relative to a soluble marker continuously infused intraruminally, were usually less than 20% of corresponding rumen fluid concentrations. It was estimated that the amount of protozoal nitrogen leaving the rumen represented less than 2% of dietary N.3. Passage of volatile fatty acids (VFA) from the rumen in effluent was less than 75% of that indicated by rumen concentrations.4. A continuous, in vitro fermentation system was developed, in which outputs of protozoa were comparable with in vivo outputs.