Synchronisation of oestrus, induction of ovulation and batch farrowing of sows

Litters of 77 pluriparous sows were weaned at 35 days after parturition in groups of 3 to 5 sows. Oestrus was induced 24 hours later with 750 IU eCG and, after a further 56-58 hours, ovulation was induced with 5 mu g of synthetic GnRH. On days 4 and 5 post weaning, 24 and 36 hours, respectively, after the administration of hormones, all sows were artificially inseminated. Forty-eight sows were not included and acted as controls. All sows in the experimental group came into oestrus 4 to 5 days after weaning, but oestrus was only observed in 50% of the control group within 8 days of weaning. The insemination index was reduced from 1.2 to 1.0, whereas the percentage of pigs becoming pregnant after the first insemination increased from 8.3% to 97.4%. The mean litter size was 12.4 in the experimental group and 11.6 in the control group.