Total salivation in grazing lambs

Abstract

Recordings were made of the resting secretion rates of total saliva in grazing lambs from 13 to 86 days of age and from 2-year-old grazing wethers. The saliva was collected froin conscious animals by means of an oesophageal fistula. In certain cases the two parotid ducts were temporarily cannulated and separate but simultaneous collections were made of the secretions from the two parotid ducts and of the residual saliva. During the first 4 weeks or life the rate of total salivation by the lambs was extremely low, but it then rapidly increased until by 5 weeks of age they had reached the range of the adult sheep. However, the separate collections from the parotid cannulae and the oesophageal fistulae indicated that the rate of residual secretions had not fully reached adult levels by the time the lambs were 88 days old. In the adults the residual saliva comprised approximately 41% of the total secretion but in the lambs there was only approximately 26% of residual saliva. Analyses of the nitrogen, sodium, and phosphate levels in the samples collected showed that the composition of total saliva did not alter from 32 to 88 days of age, and that the parotid saliva contained less nitrogen and more sodium than the residual saliva.