Quantitative digestion of fresh herbage by sheep: IV. Protein synthesis in the stomach

SUMMARY The proportions of bacterial and dietary protein entering the duodenum of sheep fed fresh herbage were assessed using 2,6-diaminopimelic acid as a marker. The herbages fed were Lolium perenne L., ‘Grasslands Ruanui’ perennial ryegrass; L. (perenne × multiflorum) , ‘Grasslands Manawa’ short-rotation ryegrass; Trifolium repens L., ‘Grasslands 4700’ white clover. The dietary protein degraded in the stomach was approximately 70% for all herbages. The bacterial contribution to protein entering the duodenum was 43·1, 57·1 and 52·9% for Ruanui, Manawa and white clover respectively. Protein entering the duodenum contained only a small amount of protozoal protein. Bacterial protein synthesis in the stomach was different for all three herbages, averaging 16·2, 30·7 and 19·8 g/100 g organic matter apparently digested for Ruanui, Manawa and white clover respectively. It is suggested that the micro-organisms digesting Manawa synthesized protein more efficiently.