A Note on the Effect on the Kidneys and Livers of Feeding Urea to Steers Fattening in Dry Lot and on Pasture

Abstract

These studies show that urea fed for long periods of time to steers under dry lot management at the rate of 0.88 and 2.29 per cent of the dry matter of the ration does not cause liver or kidney damage. They also show that urea, when fed to steers on pasture at the rate of 0.18 and 0.35 pounds per head per day, and as complete replacement for cottonseed meal supplement, does not cause liver or kidney damage. These observations are significant in view of the fact that Hart and his co-workers have shown that kidney damage is present when urea is fed at the rate of 4.3 per cent of the dry matter of the ration and is also apparent when it is fed at the 2.8 per cent level. This suggests that the harmful level of urea feeding for cattle may be between 2.29 and 2.8 per cent of the dry matter of the ration. This conclusion cannot be extended to all ruminants because Harris and Mitchell (1941) have shown that when urea is fed to wethers at the rate of 3.15 per cent of the dry matter of the ration kidney damage does not occur.