Correlation between ruminal degradability of crude protein in situ and in vitro protein foods of plant origin

Abstract

The objective of this work was to evaluate the correlation between ruminal degradability of crude protein (CP) in situ and in vitro protein foods of vegetable origin. The evaluated foods were bran soybeans, lupine, extruded lupine, rape cake, extruded rape cake, peas and extruded peas. The in situ ruminal degradability evaluation was carried out at the Maquehue Experimental Station of the University of La Frontera, using two Frisonas cows, fistulated with ruminal cannula. The foods were evaluated in 2, 4, 8, 12, 24 and 48 hours of ruminal incubation. The in vitro method was based on the use of Streptomyces griseus proteases, each food was analyzed in triplicate. Pearson correlation analysis was performed between determinations of in situ and in vitro degradability. A value of p <0.1 was used. The ruminal degradability values of CP obtained in vitro tend to underestimate the degradability values obtained in situ. The Pearson coefficient obtained is high (r = 0.67) (y = -38.2356 + 0.7741 * x, r2 = 0.4420, p = 0.072). The variability found is a characteristic of the in vitro methods, which can be improved by increasing the number of foods analyzed. It is feasible to use the enzymatic technique to estimate the rumen degradability of the CP of protein foods, however it requires the inclusion of a correction factor.