Induction of parturition in swine with a prostaglandin analog and oxytoxin: A trial involving dose of oxytocin and parity.

The purpose of this experiment was to compare a range of oxytocin doses in order to find the most suitable dose to improve predictability and precision of timing of PGF-induced parturition in sows. Sows randomly allotted to 6 groups - group size varying between 28 and 39 - were either untreated controls (group 1) or received an IM injection of 2 mg of the PGF-analog Alfaprostol (Vetem) on day 111 of pregnancy (day 0 = last day of standing heat), followed 20 h later by 0, 5, 10, 20 or 30 IU oxytocin, respectively (groups 2 - 6). Both length and variability of the time from injection of oxytocin to the onset of parturition decreased with increasing dose. The response was faster and more predictable with older sows than with first litter gilts. A disadvantage of higher doses of oxytocin was the necessity of manual aid (11 % in controls, 52 % with the maximum level of 30 IU oxytocin). Litter size, weight and percentage of piglets weaned and time from weaning to subsequent estrus were not affected by any of the treatments. An oxytocin dose of 20 IU applied 20 h after PGF appeared to give the most effective response, although this will occasionally necessitate manual assistance with parturition.