EFFECT OF EXOGENOUS GONADOTROPINS ON THE WEANING-TO-ESTRUS INTERVAL IN SOWS

Abstract The efficacy of PG 600 (400 IU PMSG and 200 IU hCG) for accelerating the onset of estrus was determined for sows weaned during the summer. Yorkshire sows (average parity = 4.6), nursing 8.6 ± 0.2 pigs (mean ± SEM) were weaned after 27.7 ± 0.4 d of lactation and were treated intramuscularly with either PG 600 (n = 35) or with 0.9% saline (n = 35). Sows were checked for estrus once daily in the presence of a mature boar. Treatment with PG 600 increased (P 0.1) for sows treated with PG 600 and with saline, and was 12.7 ± 0.6 and 11.7 ± 0.7, respectively. Pigs farrowed by saline-treated sows, however, tended to be heavier (P