Bioscientifica Proceedings

Litter size is often proposed as the trait that could have the greatest impact in improving reproductive efficiency of pigs. Efforts to select directly for increased litter size have generally been unsuccessful and highly variable. As a result, several attempts have been made to identify critical physiological components that control litter size, with the underlying assumption that augmenting these components would improve this important trait. One attempt at improving p...

In pigs, as in other species, fetal growth retardation is associated with reduced birth weight and increased risk of fetal and neonatal death. As there are few opportunities after birth to remedy the detrimental effects of low birth weight, it is important to understand both the intrinsic and extrinsic factors associated with inadequate fetal growth and to determine when growth retarded fetuses deviate from the growth trajectory of their normal sized littermates. Inadequately ...

The pig industry is confronted with substantial losses due to piglet mortality. With 3-8% stillbirths and generally > 10% preweaning mortality, approximately one fifth of al I fetuses formed fully at the end of gestation die before weaning. Most of these losses occur in the perinatal period. Overall prenatal development (birth weight) and specific prenatal developmental and maturational processes in late gestation are predisposing factors for perinatal losses. Birth weight ...

Pigs begin behavioural preparations for birth about 1-2 days before parturition. Prepartum sows wander to select a suitable site and then construct a maternal nest. The signal that initiates this behavioural cascade probably results from fetal maturation but is unknown. However, endogenous PGF2a appears to be involved early on in an endocrine pathway that projects to the brain and can generate most of the prepartum behavioural components. This period of intense activity ...