Studies on salivary lipase in young ruminants

Abstract

1. The presence of a lipase in the saliva of young calves, lambs and goat kids has been established. 2. The lipase acts only on triglycerides containing butyrate groups. 3. The optimum temperature for the activity of the salivary lipase lies between 37 and 42 ·5℃. It is inhibited completely by temperatures below 11℃ and above 58℃. 4. The optimum pH for the enzyme was found to be between pH 4 · 5 and 6 · 0. It was completely inhibited by pH below 2·4 and above 7·8. 5. A direct relationship exists between the potency of the lipase and the amount of acid it will produce in suitable substrates. 6. The lipolytic potency of the saliva of young calves and goats has been shown to decrease with increasing age. It decreased more rapidly in calves fed high roughage and low fat rations than in calves fed on whole milk only. In calves fed by the conventional methods, the enzyme disappeared from the saliva during the third month of life. 7. The secretion of the enzyme is stimulated by the calf sucking a teat or drinking milk. Sucking milk from a teat acts as a better stimulus than drinking milk from a bucket. Slower intake also stimulates lipase secretion. 8. The injection of cholinergic drugs caused increased flow of saliva with a higher lipase content. Anticholinesterases also stimulated its secretion but to a lesser degree. 9. The salivary lipase is secreted by the palatine salivary glands (glandulae veli palatini).