Investigate the magnitude of differences in total metabolizable protein among different genotypes of barley grown for three consecutive years

Abstract

Several genotypes of barley have been developed by Crop Development Center. However, no quantitative evaluation of true protein supply to ruminants has been done in terms of protein degradation balance (PDB) and total metabolizable protein supply (or total truly absorbed protein in the small intestines). The objective of this study was to determine the magnitude of difference in terms of total metabolizable protein supply of five CDC feed-type barley cultivars in comparison to Canada’s most widely grown malting cultivar AC Metcalfe. Six, two row cultivars of spring sown barley, included AC Metcalfe, CDC Cowboy, CDC Dolly, CDC Helgason, CDC Trey and McLeod were grown in the research field of University of Saskatchewan, Saskatoon, SK, Canada for three consecutive years. The quantitative predictions were made in terms of: 1) Rumen synthesized microbial protein truly absorbed in the small intestine (AMCP); 2) Rumen undegraded protein truly absorbed in the small intestine (ARUP); 3) Endogenous protein in the digestive tract (AECP); 4) Total metabolizable protein supply in the small intestine. The results showed that CDC barley variety differed (P 0.05) in ARUP with average of 48 g/kg DM. Total metabolizable protein ranged (P < 0.05) from 85 to 92 g/kg DM. In conclusion, CDC barley variety affected total predicted metabolizable protein supply, but not to large extend. All the barley varieties had negative degraded protein balance value.