Abstract
This study was carried out as an observational study in order to examine the difference of change in serum very low-density lipoprotein (VLDL) between primiparous and multiparous cows. Twenty-one clinically healthy cows (10 primiparous and 11 multiparous) were selected at 21 days prior to expected calving. Blood samples were collected in the morning (before feeding) on days -21, -7, 7, 21 and 56 days in milk (DIM). At 7 and 21 DIM, the serum non-esterified fatty acid concentration of multiparous cows was significantly higher than that of primiparous cows. The serum β-hydroxybutyrate concentration was also markedly higher in multiparous cows than in primiparous cows at 21 DIM. These results suggested that the degree of negative energy balance was greater in multiparous cows than in primiparous cows during this period. In both, serum VLDL concentrations decreased at over 7 DIM, increased at 21 DIM, and then decreased at 56 DIM. On the other hand, triglyceride and total protein concentrations of VLDL in multiparous cows were significantly lower than in primiparous cows at 21 DIM. This suggests that multiparous cows have poor triglyceride secretion from the liver and that they become more susceptible to hepatic lipidosis.