Apolipoprotein (
apo) C-III is a low-molecular-mass
protein mainly distributed in the
high-density lipoprotein fraction in cattle serum. We have recently shown that the
apoC-III concentration is decreased in cows with
fatty liver,
ketosis, left displacement of the abomasum,
retained placenta and milk
fever. The decrease was most distinct in milk
fever, thereby suggesting that
apoC-III is particularly relevant to the development of milk
fever and also that
apoC-III is a candidate diagnostic marker for this disease. The purpose of the present study was to examine whether the
apoC-III concentration in healthy cows is altered during the peripartum period, to assess the usefulness of
apoC-III as a marker for milk
fever.
ApoC-III concentrations in 17 cows were monitored during the peripartum period (-48 to +12 days from parturition). Of the 17 cows, 14 were apparently healthy during the period. The
apoC-III concentrations in the 14 healthy cows were unaltered during the period from -48 to -21 days, but thereafter showed individual variations. Compared with values during the period from -48 to -21 days, the
apoC-III concentration was increased (137%) in 5 cows during the period from +1 to +12 days, whereas it decreased (60.7%) in 9 cows. Three cows suffered from milk
fever at -3 to +10 days. Decreased
apoC-III concentrations in diseased cows (15 to 37% of controls) were more distinct than in the 9 healthy cows. The
apoC-III concentration was correlated with
lecithin:cholesterol acyltransferase activity in cows with milk
fever, but not in healthy cows. Correlation analysis also indicated that
apoC-III and
apoB-100 concentrations were negatively correlated in 5 healthy cows with increased
apoC-III concentrations, but positively in 9 healthy cows with decreased concentrations and cows with milk
fever. Determination of the
apoC-III concentration during the peripartum period is suggested to be helpful in diagnosing milk
fever. The possible relevance of
apoC-III and
apoB-100 in the development of milk
fever is also implied.