Oxytocin precipitation of prostaglandin-induced farrowing in swine: determination of the optimal dose of oxytocin and optimal interval between prostaglandin F2 alpha and oxytocin.

The influence of dose of oxytocin and the interval between prostaglandin (PG) F2 alpha and oxytocin administration on the synchrony of farrowing, the prevalence of intrapartum complications, and the number of pigs dying perinatally was investigated. In study 1, sows were given 10 mg of PGF2 alpha IM on day 112, 113, or 114 of gestation or were not treated. Twenty hours after PGF2 alpha administration, sows were given 0, 5, 10, 20, or 30 USP U of oxytocin IM. Sows treated with PGF2 alpha or PGF2 alpha plus oxytocin had a shorter interval to farrowing than sows not treated or treated with oxytocin alone. Treatment with PGF2 alpha plus 30 U of oxytocin induced the most rapid onset and the greatest synchrony of farrowing, with the mean onset occurring 2.1 +/- 0.4 hours after oxytocin vs greater than 8 hours for all other treatments. Sows treated with 5 or 10 U of oxytocin had a delayed onset and a less synchronous farrowing, compared with sows treated with 0 or 20 U. Day of PGF2 alpha treatment influenced (P less than 0.05) the interval from oxytocin to onset of farrowing. As day during gestation decreased, there was a corresponding decrease in the interval between oxytocin administration and farrowing. Number of interventions to remove retained pigs was not influenced (P greater than 0.05) by day of PGF2 alpha administration. All sows treated with PGF2 alpha followed by oxytocin had a higher rate of manual interventions, compared with that in sows given PGF2 alpha but not oxytocin.(ABSTRACT TRUNCATED AT 250 WORDS)