Some effects of anaesthesia, lateral recumbency and diversion of saliva on the rumen function of sheep

Abstract

The effccts of anaesthesia, lateral recumbency, and the collection of saliva on the rate of contraction, pressure, total volatile fatty acid (V.F.A.) concentration, and pH of the rumen, and on the salivary secretion were investigated.

Anaesthesia depressed the rate of contraction by the rumen, significantly increased the pressure of gas within the rumen as measured at the fistula, and reduced the rate of total salivary secretion by 66%. Anaesthesia had no effect on the concentration of nitrogen in the total mixed saliva, and its effect on the concentration of rumen total V.F.A. was inconclusive.

During lateral recumbency a high concentration of rumen total V.F.A. was maintained. There was no change in the rate of contraction of the rumen, but there was a rise in the gas pressure measured at the rumen fistula and a decrease in the rate of total salivation. A significant increase was recorded in the total saliva nitrogen concentration.

When total saliva was collected from the oesophageal fistulae of standing sheep, the pattern of total V.F.A. concentration within the rumen was altered. There was no change in the rate of contraction of the rumen or in the gas pressure at the rumen fistula. It was concluded that the diversion of 2 1. of saliva over a 5 hr period had little effect on the sheep provided the sodium loss was subsequently restored.

It is suggested that care is needed in interpreting results obtained from sheep under anaesthesia or in lateral recumbency.