The experiment was conducted on 9 Merino sheep with an average body weight of 50 kg, with catheters in the common bile duct and a T-cannula in the duodenum. The animals were assigned to three groups with three animals in each and fed diets (in the amount of 1200 g/d) composed of meadow hay, rapeseed meal, and potato starch (group P), maize starch (group M) or wheat starch (group W) in low (L), medium (M) or high (H) level. After 14 days of adaptation to the diets, the mixture of pancreatic juice and bile was collected for three successive days from 8:00 to 16:00 h. The volume of the secretion was highest when diet HP was fed (1395 ml/8 h) and lowest on diet LW (662 ml/8 h) (P < 0.01). The highest amount of total N was found when diet HP (2 g/8 h) was fed, the lowest (1.3 g/8 h) when diet LM was provided. The activity of α-amylase (U/ml) was highest on diets HW (P < 0.01) and HM (P < 0.5), trypsin, on diets MP, MM and LW (P < 0.01), chymotrypsin, on diet LW (P < 0.01). It can be concluded that differences in the activity of enzymes were significant between some diets, however there were no regular trends indicating a general dependence on the level or kind of starch.