Concentrations of apolipoprotein C-III in healthy cows during the peripartum period and cows with milk fever

Apolipoprotein (apo) C-III is a low-molecular-mass protein mainly distribut ed in the high-density lipoprotein fraction in cattle serum. We have recent ly shown that the apoC-III concentration is decreased in cows with fatty li ver, ketosis, left displacement of the abomasum, retained placenta and milk fever. The decrease was most distinct in milk fever, thereby suggesting th at apoC-IIT is particularly relevant to the development of milk fever and a lso that apoC-III is a candidate diagnostic marker for this disease. The pu rpose of the present study was to examine whether the apoC-III concentratio n in healthy cows is altered during the peripartum period, to assess the us efulness 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 t he 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 con centrations in disease d cows (15 to 37% of controls) were more distinct than in the 9 healthy cow s. The apoC-III concentration was correlated with lecithin:cholesterol acyl transferase activity in cows with milk fever, but not in healthy cows. Corr elation analysis also indicated that apoC-III and apoB-100 concentrations w ere negatively correlated in 5 healthy cows with increased apoC-III concent rations, but positively in 9 healthy cows with decreased concentrations and cows with milk fryer. Determination of the apoC-III concentration during t he peripartum period is suggested to be helpful in diagnosing milk fever. T he possible relevance of apoC-III and apoB-100 in the development of milk f ever is also implied.