Bioscientifica Proceedings

The number of female germ cells in pig fetuses decreases by 70% between day 50 after mating and day 300 after birth. Approximately 55% of antral follicles undergo degeneration (atresia) except during the 3 days before oestrus, when only 15% of the follicles survive to ovulate. Apoptosis, a form of programmed cell death, is recognized as the mechanism of germ cell death and follicle atresia at all stages of folliculogenesis. The internucleosomal cleavage of genomic DNA ca...

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...

Studies in different animal models and humans give evidence that stress experienced by pregnant mothers affects foetal development and has long-term consequences on many physiological systems and behaviour in the offspring, thus facilitating the risk for disorders later in life. In farm animals, housing conditions or inadequate management practices during gestation may be potential stressors for the mother, which could affect growth, vitality, health and welfare of the d...

Abstract unavailable© 2013 Context Products Ltd...

Summary. Follicular development during early lactation in the sow is characterized by a large population of small-sized follicles and a small population of medium-sized follicles. As lactation progresses there is a gradual shift in number of follicles into medium- or large-sized categories and the percentage of follicles classified as atretic declines. Weaning at birth often leads to aberrant follicular development, apparently because the positive feedbac...

Summary. In the pig, establishment of pregnancy begins about 11-12 days after the start of oestrus. The ability of pig conceptuses to synthesize and release oestrogens during this period, as well as the ability of exogenous oestrogens to induce pseudopregnancy when administered from Day 11-15 of the oestrous cycle, provide evidence for an involvement of oestrogen in the maternal recognition of pregnancy in the sow. Oestrogen derived from the conceptus or ...

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 ...

A new method for non-surgical deep intrauterine catheterization of pigs, without sedation of the sow, is described. Insemination results obtained with this method using fresh spermatozoa demonstrate that, in comparison to conventional artificial insemination (Al) (3 × 109 spermatozoa in 80-100 ml), a 20-60-fold reduction in the number of spermatozoa inseminated and at least a 8-10-fold reduction in the dose volume can be used without affecting fertility ...

Although cryopreservation of boar semen for artificial insemination (Al) was developed 35 years ago, cryopreservation conditions and Al strategies are still considered sub-optimal. Al with excessive numbers of frozenthawed sperm (5-6 x 109 cells), still does not achieve fertility levels similar to Al using liquid semen because of reduced sperm survival. Frozenthawed (FT) spermatozoa have therefore not been the preferred option for commercial breeding programme...

Abstract unavailable© 2009 Society for Reproduction and Fertility...