Estimating ruminal crude protein degradation of feeds using in situ and in vitro techniques

摘要

The aim of this study was to estimate the proportion of feed crude protein (CP) escaping degradation in the rumen (RUP) using in situ {in sacco) and in vitro methods. In sacco experiments were carried out on three nonlactating cows with large rumen cannulae. To determine in vitro crude protein degradability (CPD) were used: A. commercial enzyme Streptomyces griseus protease (P5147, Sigma, 2.66 U/mg) and B. lyophilised rumen cell-free fluid. CPD of extracted soybean meal, extracted sunflower meal, fresh grass and grass silage were determined. Incubation was done for 12 and 24 hours to compare the differences between the methods, time of incubation and the interaction between the time of incubation and the method. CPD (in sacco) was after 12 hours from 81.5% (soybean meal) to 86.1%o (sunflower meal), CPD (in vitro) with commercial enzyme was from 70.3%) (soybean meal) to 84.9% (sunflower meal), and for cell free ruminal fluid from 12.9% (soybean meal) to 54.3% (grass silage). The advantage of commercial enzyme is the stability of its activity. The in vitro method with enzyme S. griseus protease can be used in parallel to the in sacco method to estimate degradation of various feeds.