Hormonal changes during parturition in heifers and goats are related to the phases and severity of labour

Abstract

Parturition is a natural event that involves stress and pain for the mother. We thus hypothesized that levels of stress hormones measured during parturition could reflect levels reached in response to severe discomfort and pain of other kinds as well. The aim of this study was therefore to determine whether plasma concentrations of cortisol, adrenaline, noradrenaline, -endorphin, met-enkephalin, vasopressin and oxytocin vary depending on the phase and severity of labour in dairy heifers (ten) and dairy goats (six), and how these hormones interact with each other. Blood samples were taken once a day for 3 days before labour and for 3 days afterwards and at predetermined phases during labour. All heifers delivered one calf and five of them needed obstetrical assistance. Two of the goats delivered one kid, and four had twins; all kidded without help. The cortisol concentration peaked when the calf and the first kid were born. In the heifers, plasma adrenaline increased after delivery, while the noradrenaline concentration did not change significantly in heifers that needed assistance, but increased during expulsion in heifers calving without help. In the goats, adrenaline and noradrenaline concentrations increased in association with expulsion of the first kid. The -endorphin concentration increased during labour in goats. In heifers that needed assistance, -endorphin concentration increased 1 h after labour but there was no change in heifers that did not need assistance. The met-enkephalin concentration was elevated during expulsion in heifers and fluctuated in the goats. Both oxytocin and vasopressin increased during expulsion in both groups of heifers, but vasopressin increased four times more in heifers needing assistance. In the goats, oxytocin reached its highest levels just as the feet of the first kid became visible, and vasopressin peaked as the head emerged. Parturition took longer in heifers that needed assistance than in those that did not. It is concluded that, even though the pattern of change differed between hormones during labour, the changes were related to the phases of labour. A longer labour therefore meant that the hormone concentrations stayed elevated for longer. Vasopressin reached high levels in goats and was the only hormone for which plasma concentrations were higher in heifers that needed assistance than in those that did not, indicating that this hormone is released in order to deal with the painrelated stress associated with labour.

The relation between the birth process and the condition of the newborn piglet and calf

“…It is only during the last hour before expulsion that a more sustained hypoxia and acidosis develops, most probably as the result of a more permanent reduction in uterine blood flow. The latter is caused by hyperstimulation of uterine contractions, because plasma oxytocin reaches peak levels at this late stage of delivery (Hydbring et al 1999), and by involution of the now unoccupied distal part of the uterine horn. A recent study, using ultrasonic transit-time measurements of umbilical blood flow during second stage labour, demonstrated that in calves born with a jugular blood pH<7.2, umbilical blood flow significantly decreases at the end of the expulsive stage; blood flow in the umbilical arteries and vein even ceased completely during passage of the calf's head through the vulva (Bleul et al 2007).…”

Placenta functions with special emphasis on endocrine changes – a comparative overview

“…Königsson et al [26] reported that after dexamethasone-induced parturitions distinct peaks of cortisol were only seen in cows with retained foetal membranes. This might be due to some kind of stress due to prolonged or difficult calving as suggested by Hydbring et al [25], but might also be due to an effect of the retained foetal membranes per se. Cows delivering the placenta at normal time did not have any peaks of cortisol [26].…”

“…The levels of cortisol in the maternal blood circulation are very high during the time of parturition [23]. These rising levels were reported to be related to the stress condition with labour [24,25]. Twin-bearing cows had significantly higher mean plasma cortisol levels on the day of parturition than the singleton cows [24].…”

Correlation between behaviour during labour and blood plasma concentrations of vasopressin in goats

“…Labour is a natural event associated with pain. Apart from the hormones known to be directly involved in the birth process in goats, blood plasma vasopressin concentrations increase to high levels at the birth of the fi rst kid and then decline (Hydbring et al, 1999). The reason for this is not clear, but it was suggested that the high levels were correlated to the pain during the phase of cervical dilatation.…”