Metabolism of the soluble carbohydrates of grasses in the rumen of the sheep

Abstract

1. The bacteria and protozoa from the rumen of the sheep have been examined for their invertase activity.2. Washed suspensions of protozoal fractions obtained from the rumen were rich in invertase, and the greater part of the total activity in the rumen could be ascribed to the holotrich protozoa.3. Rumen streptococci capable of fermenting sucrose and fructan were isolated in pure culture. Their invertase was found to be an adaptive enzyme.4. Fermentation of the soluble carbohydrates of grass was studied in an ‘artificial rumen’. The micro-organisms converted 30% of the substrates into storage starch.5. Rumen contents from a grass-fed sheep were twice as active towards grass carbohydrates as those from hay-fed sheep.6. The hay and grass fed to the sheep contained invertase activity.