Serum Ornithine Carbamoyltransferase Activity and Correlation with Fatty Liver in Dairy Cows with Displaced Abomasum

Abstract

Ornithine Carbamoyltransferase (OCT) is a hepatocyte-specific enzyme; elevated serum activity indicates liver damage. Displaced abomasum frequently occurs around the time of parturition in dairy cattle and is associated with fatty liver. We analyzed serum OCT activities to investigate the relationship between displaced abomasum and fatty liver. Lactating Holstein cows, 75 clinically healthy and 22 with displaced abomasum, were used. Serum OCT activities were compared between healthy cows and those with displaced abomasum. Liver biopsies of cows with displaced abomasum were classified by the severity of fat accumulation. Blood samples were collected preoperatively and at 4 and 8 days after surgery and analyzed for serum OCT, aspartate aminotransferase, alkaline phosphatase, γ-glutamyltransferase, urea nitrogen, total protein and hematocrit. Serum OCT activity was significantly higher in cows with displaced abomasumthan in healthy cows. The degree of fatty liver in cows with displaced abomasum was classified as mild (13 cows), moderate (5 cows), or severe (4 cows). Statistical analysis revealed no significant differences in blood test results among cows with different degrees of fatty liver. However, our results indicated significant differences in serum OCT, aspartate aminotransferase, urea nitrogen, total protein and hematocrit when stratified by the number of days after surgical treatment for displaced abomasum. Serum OCT activity is increased in dairy cows with displaced abomasum and the influence of the degree of fatty liver on serum OCT activity is unclear. Therefore, OCT should be reconsidered as a marker of fatty liver in cows around the time of parturition, when displaced abomasum frequently occurs. Fatty liver should be evaluated by various clinical parameters, not by one hepatic enzyme.