Determinations of umbilical cord beta-endorphin concentration and blood gas parameters in newborn piglets.

Neonatal mortality is a severe welfare problem in the pig industry, with the majority of neonatal deaths occurring in those piglets born later in the litter. The purpose of this study was to assess the possible link between the release of beta-endorphin, hypoxia and birth order in newborn piglets. Blood samples were taken from the umbilical cord of piglets from 16 litters at either spontaneous or cloprostenol-induced parturition. The mean (SEM) beta-endorphin concentration in cord plasma of all piglets was 276.1 (90.28)pmol litre-1 which was significantly higher than the average concentration of 73.1 (18.54)pmol litre-1 in gilts. Neither beta-endorphin nor blood gas parameters were affected by cloprostenol. A significant (P > 0.01) peak concentration of beta-endorphin was found in the piglets born four-fifths of the way through the litter. There was a significant negative correlation (P > 0.05) between cord pH and beta-endorphin concentrations. Furthermore, the concentration of beta-endorphin was positively correlated with cord pCO2 (P < 0.01). These results indicate that the release of foetal beta-endorphin is associated with the degree of acidosis in the piglets during delivery.