Abstract: Four primiparous Holstein cows with cannulas in the rumen and proximal duodenum were randomly assigned to four diets with a 4×4 latin square experiment. Cows in four treatment were fed high forage（60%DM） diets without oil supplement（CK）, 4% soybean oil（LOC1）, 4% linseed oil（LOC2） or mix of 2% soybean oil and 2% linseed oil（LOC3） on dry matter basis. The objective was to examine the effects of supplemental fat on intake, apparent ruminal digestibility, and total tract digestibility of DM,OM,NDF and ADF in dairy cows. The results indicated that intake, apparent ruminal digestibility, and total tract digestibility of DM,OM,NDF,ADF were not affected by the oil supplementation(P＞0.05）,however the fat supplement tended to reduce the digestibility of DM,OM,NDF,ADF on rumen and total tract.

Key words: dairy cow; linseed oil; soybean oil; digestibility