Abstract
The aims of this study were to determine profiles of plasma immunoreactive β-endorphin (ir-β-EP) during peripartum period in dairy cows, and to examine whether dystocia, retained placenta or body condition affects the plasma ir-β-EP level. Blood samples were collected from 21 Holstein-Friesian cows from day 180 of pregnancy until first ovulation. The cows were classified into two groups based on calving conditions and ir-β-EP patterns at parturition. Seven out of the 21 cows had normal parturition and 14 cows had abnormal parturition (dystocia and/or retained placenta). The proportion of cows which had ir-β-EP elevation at parturition tended to be higher in cows with abnormal parturition (11/14; 79%) than in those with normal parturition (3/7; 42%). Plasma cortisol level increased at parturition both in cows with ir-β-EP elevation and in cows without ir-β-EP elevation at parturition. Postpartum ir-β-EP concentrations in plasma were similar between cows with normal parturition and those with abnormal parturition, and between cows which had lost their body condition score (BCS) after calving and those which had maintained their BCS. In conclusion, abnormal parturition may affect plasma ir-β-EP level at parturition but not postpartum period.
