[Control of fertility outcome in artificially inseminated gilts and old sows. 2: Addition of oxytocin to boar semen. Its effect on length of insemination, pregnancy rate and litter size].

Toleration-oriented insemination was applied to 1,373 oestrous sows that had undergone bio-engineering treatment, with two insemination portions having been used for each oestrous. Five International Units of oxytocin were added immediately before insemination proper to the semen applied to 315 gilts and 377 old sows. The control group included 296 gilts and 385 old sows inseminated in parallel. Semen intake, on average, was complete between four and eight minutes with the majority of gilts and between four and seven minutes with most of the old sows, but no evidence was obtained as to any action of the oxytoxin upon intake intensity. The treated gilts were superior to the controls by 6.3 per cent in pregnancy rate and by 56 born piglets to each 100 first inseminations. Superiority, consequently, was significant. In both gilts and old sows added oxytocin prolonged insemination by more than five minutes and gave clearly better fertility results.