DIGESTIBILITY OF PEA PROTEINS BY PRE-RUMINANT CALVES

Abstract

Two milk replacers, formulated to provide one-half the dietary protein from either pea protein concentrate (PPC) or pea protein isolate (PPI), were compared with a milk replacer based on reconstituted skim milk (SM). The milk replacers were fed to pre-ruminant Holstein-Friesian calves aged 3–23 days and dry matter and protein digestibilities were determined. The mean protein digestibilities of the SM (control) and PPI milk replacer were 84.0 and 75.4%, respectively (the difference was not statistically significant), and were greatly superior to that of the PPC milk replacer (47.5%). The PPC contained, on dry matter basis, 61.2% protein, 5.5% starch and 9.8% total sugars. The sugars detected were sucrose (3.7%), raffinose (1.5%), stachyose (3.3%) and verbascose (2.5%). The PPI contained 92.8% protein and less than 1.0% starch or total sugars; the only sugar detected was sucrose (0.7%). Lactose was the only sugar present in SM. Although other factors cannot be ruled out, it was concluded that starch and oligosaccharides were mainly responsible for the poor digestibility of the pea proteins in the PPC milk replacer.