Bioscientifica Proceedings

Sheep derived from the Booroola Merino strain carry an autosomal mutation (FecB) that increases ovulation rate and litter size. One approach to characterize the genetic mutation is to locate the gene using positional cloning. The locus has been mapped to a region between genes for secreted phosphoprotein 1 (SPP1) and epidermal growth factor (EGF) on sheep chromosome 6. Analysis of possible candidate genes have excluded a number of genes associated with control of repr...

Widespread adoption of artificial insemination as a breeding practice has allowed for expanded use of desirable genetics from specific sires and greatly influenced production traits in dairy cattle populations worldwide. In fact, the average dairy cow in the US in 2009 produced 4.5 times more milk than in 1940 when commercialization of artificial insemination began. While many factors have contributed to this rapid increase in levels of milk production, genetic gain through ex...

Inappropriate maternal nutrient intake at key developmental timepoints during ovine pregnancy has a profound influence on the outcome of pregnancy and aspects of postnatal productivity. However, the responses to alterations in maternal nutrition in adult sheep are often highly variable and inconsistent between studies. The growing adolescent sheep provides a new, robust and nutritionally sensitive paradigm with which to study the causes, consequences and reversibility of prena...

Abstract unavailable© 2013 Context Products Ltd...

Abstract unavailableKeywords: ovary; ovarian follicles; granulosa cells; growth factors; insulin-like growth factors© 1991 Journals of Reproduction & Fertility Ltd...

Abstract unavailable© 2013 Context Products Ltd...

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...

Despite the great potential of sperm technologies such as sperm cryopreservation and sperm sex sorting for the improvement of different aspects of swine production, artificial insemination with fresh or stored semen is currently the only sperm technology used at a commercial scale in the pig industry. The lower reproductive performance associated with the use of these sperm technologies is the reason for such limited use. Since optimal characteristics are required for su...

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

Commercial, North American pork breeds (Sus sada) experience significant loss of genetically-normal conceptuses during the peri-implantation (attachment) period and at mid-gestation (day 50 to 90 of the 114 day porcine gestation interval). Although exact causes for these losses are not defined, asynchronous in-utero development and deficits in vascularization of the endometrium and placenta appear to be involved. Understanding of normal maternal-fetal dialogue is critica...