The true absorption of cyst(e)ine from the ovine small intestine.

Na234SO4 was infused into the rumen of a sheep fed a dried grass diet. 2. The digesta at the pylorus which contained 35S-labelled cyst(e)ine synthesized by the rumen microflora was collected and mixed with chromium EDTA. This material was infused into the duodenum of 35S free sheep. 3. Ileal digesta was subsequently collected and analysed for cyst(e)ine 35S and Cr. 4. The proportion of the labelled cyst(e)ine truly absorbed from the small intestine was 0-72 +/- 0-004.