Leptin - Endocrine Signal Regulating the Onset of Post-weaning Estrus in Pigs

Introduction Profitability in the swine industry is based on prolificacy. One measurement of prolificacy is the number of piglets produced per year. To optimize prolificacy and profits it is essential that sows are re-bred as soon as possible after weaning. An extended post-weaning anestrus decreases overall productivity and increases costs of production. A large number of sows undergo prolonged postpartum anovulatory periods. Furthermore a significant number of sows, after having their first litter never return to estrus and are removed from the herd. Many factors influence the duration of the weaning-to-estrous interval including: parity, season, duration of lactation, breed and nutritional status (Kirkwood et al.,1984; Aherne and Kirkwood, 1985; Clark et al., 1986; Dial et al., 1987).