My research has focused on the control of reproductive function, particularly ovarianfunction in farm animal species. It has included the study of the mechanisms controllingfollicular growth, ovulation rate control and corpus luteum function. Experimentalapproaches have included comparisons between mono- and poly-ovular species,between breeds of sheep with differing ovulation rates and utilising genetically selectedlines of sheep. The work has included the development of a novel ovariantransplantation approach in large animal species for maintaining fertility after lowtemperature freezing. As well as providing an excellent large animal model to study therecruitment of primordial follicles and follicle development to ovulation, it is currentlybeing extended to the development of whole ovary cryopreservation and transplantation.
he research has involved the delineation of the importance and roles ofgonadotrophins, metabolic hormones and locally-produced growth factors in folliculargrowth and development. The results demonstrated the interaction between extra-ovarian hormones and intra-ovarian growth factors, including the importance of growthhormone and related hormones and growth factors on follicular development. Thesestudies required the development and detailed validation of a range of hormone assaysand physiologically relevant cell culture systems for follicular cells.
he importance of environmental factors, such as nutrition, was investigated. Thisincluded the demonstration of the direct effects of nutrition on gene expression withinfollicular cells to influence oocyte quality and embryo survival. Subsequent workinvestigated the underlying mechanisms of action, demonstrating the differing impactof various metabolic factors necessary for either follicular growth or the maintenanceof oocyte quality. This research enabled the formulation of diets and feeding strategiesthat significantly improved pregnancy rates in dairy cattle and which are now beingused by the industry. This work is of particular relevance in halting the decline infertility, since selection of dairy cows on the single trait of milk production was shownto result in a continuing reduction in conception rates at approximately 1% per annum.2