Nitrate reduction in the rumen of the grazing sheep

Abstract

Nitrate, a normal component of pasture, shows marked fluctuations in its concentration in the plant. Nitrate and comparatively smaIl amounts of nitrite have been detected in the rumen contents of sheep on such pasture.

The effect of adding moderate amounts of nitrate to the rumen of the grazing sheep has been studied. The rumen of the sheep on pasture is capable of handling comparatively large amounts of nitrate under normal circumstances without noticeable ill-effect. Any adverse effects due to the oxidising nature of the nitrate ion were surmounted within three to four days. The results reported tend to indicate a slight stimulation of rumen function after continuous daily nitrate dosing. Under such conditions the sheep exhibited a sustained but fluctuating methaemoglobinaemia with peak values of about 35% conversion of total haemoglobin to methaemoglobin.