Sulphur and cystine incorporation into rumen microbial protein

Abstract

1. In three series of experiments, Na 2 35 SO 4 was infused into the rumen of sheep consuming a variety of diets. The specific activity of the sulphur in the rumen H 2 S pool, rumen bacteria and of the S in bacterial cystine were determined. 2. The results showed that, depending upon the diet, the proportion of total sulphur and cystine sulphur in rumen bacteria originating in the rumen H 2 S pool could be as low as 0.557 and 0.280 respectively.