CLINICAL CHEMISTRY OF GRAIN-FED CATTLE. II. LIVER FUNCTION

Abstract

The rate of plasma clearance of bilirubin (BCR), as a test of liver function, was followed in three hay-fed and four grain-fed Hereford steers over the first 77 days of a 106-day feeding period. The grain diet was 90% steam rolled barley, 5% beet pulp pellets and 5% of a protein/mineral/vitamin concentrate given together with a hay supplement of 0.9 kg/head/day. The grain was introduced slowly over a 10-day period. Fluctuations in hematocrit values occurred during the adaptation to the grain diet. Periodic episodes of markedly reduced liver function occurred synchronously in test animals during the introduction of the grain diet. Similar episodes of reduced liver function were observed with decreasing frequency and severity as the feeding progressed. After 25 days of grain feeding, loss of synchrony also occurred, so that high values were observed in only one test animal at any one time. As the feeding period progressed, the time required for the distribution and equilibration of the bilirubin in the blood increased in the grain-fed animals causing interference with the BCR tests. The effects on liver function indicated a reduction in the efficiency of the liver which probably contributes to pathologic conditions in feedlot cattle.