Performance of young pigs: relationships with periparturient progesterone, prolactin, and insulin of sows.

Blood collected from 54 sows over 2 to 8 d of the periparturient period was assayed for progesterone, insulin, and prolactin to determine whether the sows' hormonal state was correlated with perinatal pig mortality and weight gain. Sows with larger litters had higher concentrations of progesterone and prolactin and a lower concentration of preprandial insulin during the 48 h preceding parturition. Pig mortality was higher in larger litters and involved pigs of lower birth weight. Most pigs that died lost weight during the 24 to 48 h that preceded their deaths. Litters with lower weight gain during the first 24 h postpartum tended to have higher mortality during the next 48 h. For some sows, progesterone remained elevated during the 48 h postpartum and litters of these sows had lower than average 3-d weight gains. Low milk intake by pigs is a major cause of death and poor growth, and we suggest that poor milk production by the sow is one contributing factor. Elevated postpartum progesterone may inhibit lactogenesis and contribute to poor pig performance.