Studies on lipid digestion in the preruminant calf. 2. A comparison of the products of lipolysis of milk fat by salivary and pancreatic lipases in vitro.

1. A comparison has been made of the products of lipolysis of the fat in cow's milk by salivary and pancreatic lipases (EC 3-1-1-3) from a preruminant calf. 2. It was confirmed that salivary lipase releases short-chain acids preferentially, particularly butyric and caproic acids. This was not only true initially but also as the course of lipolysis progressed. Even after 60 min incubation the longer-chain acids were only released to about one-twentieth of the extent of butyric acid. 3. Although pancreatic lipase also initially released proportionately more butyric acid than other fatty acids, within 30 min the longer-chain acids were released to about half the extent of butyric acid. 4. Since the over-all extent of lipolysis by salivary lipase was limited by its inability to release long-chain acids, the release of these acids (which comprise two-thirds of the total fatty acids of milk fat) in the calf is likely to be dependent on the subsequent action of pancreatic lipase. 5. The release of fatty acids by pancreatic lipase was enhanced by pre-incubating milk fat with salivary lipase.