It was found that when gilts newly introduced into a breeding herd had been inseminated during their first estrus after transport, the fertility rate was 7.35 lower and the number of live piglets was significantly lower in comparison with that resulting from insemination performed during the second spontaneous estrus after transport. In gilts inseminated in their first estrus after transport there were 2.32 live born piglets less than in gilts which were inseminated in the second spontaneous estrus after transport.