Fat infiltration in liver and activity of lecithin : cholesterol acyltransferase in serum of dry and lactating dairy cows

To study the relationship between fat infiltration in the liver and the dec rease in the activity of serum lecithin:cholesterol acyltransferase (LCAT), blood and liver samples were taken from 14 multiparous (MP) and 16 primipa rous (pp) dairy cows four weeks and one week before, and one, four and eigh t weeks after calving. During the dry period, half the animals received a p rotein supplement. LCAT activity decreased significantly in all groups befo re parturition, but returned to the initial level within 1-4 weeks after pa rturition. There were no differences between the feeding groups, but after calving, the LCAT activity in the MP COWS was significantly lower than in t he PP COWS. Fat infiltration was not detected in the PP cows, and in the MP COWS fat infiltration was mild and fell within the physiological range. Th ere was no correlation between liver fat content and the activity of LCAT i n serum. These results suggest that shortly before and after parturition, t he activity of LCAT in serum is limited by post-transcriptional regulation, possibly by the availability of amino acid for export protein synthesis in the liver. (C) 2000 Harcourt Publishers Ltd.