Fertility of gilts with prolonged preinsemination anestrus after progestagen-eCG treatment

The objective was to determine the effects of Regumate® alone or Regumate®+eCG treatment on the synchronization of estrus and fertility in delayed puberty (n=30+30) and normal cyclic gilts (n=30+30). Gilts were fed daily a complete diet containing 20 mg/gilt Regumate® for 18 days. Twenty-four hours after the last feeding of Regumate®, all gilts received an i.m. injection of 1,000 IU eCG. Gilts were inseminated artificially (AI) 12 and 24 h after first detection of standing estrus. More normal cyclic gilts (84.6%) than delayed puberty gilts (66.7%) expressed estrus by d 4.8 after Regumate® alone treatment (p < 0.05). However, similar proportion of normal cyclic (90%) and delayed puberty gilts (93%) were in estrus by d 4.2 after Regumate® + eCG treatment (p > 0.05). These findings indicate that about 70% of delayed puberty gilts had established cyclic ovarian activity (i.e. sexually mature, cyclic gilts), while about 30% were truly delayed puberty gilts (sexually immature, prepubertal acyclic gilts), before progestagen treatment. AI of delayed puberty gilts resulted in 80 to 85.7% farrowing rate and 10.50 to 11.04 liveborn piglets per litter. Obtained results demonstrate that progestagen treatment may be an effective tool for increasing gilts' reproductive efficiency and reducing the number of gilts culled from the breeding herd due to prolonged preinsemination anestrus