Implementation of Clinical Assisted Reproduction Technologies for the Improvement of in vitro Production of Porcine Embryos: From IVF Clinic to Pig Farm
The world population is predicted to rise from 7 to 9 billion in the next 30 years, and per capita, meat consumption is predicted to increase by 20% at this time. This places a demand on current food producers globally (particularly pork producers as 40% of global meat consumption is pig meat) that is not sustainable unless sufficient innovations are implemented. Livestock production also contributes 18% of the earth's global warming, and this is also set to increase. Solving these problems necessitates producing increased amounts of meat from fewer animals in a shorter amount of time. UK companies lead the world in developing livestock with superior genetic traits that drive increased productivity through greater feed conversion efficiencies, improved disease resistance, and higher fertility. Disseminating and applying these advances into herds around the world, however, presents unique problems. That is, for female line genetics, (male line genetics can be disseminated via sperm samples) producers are left with no other choice but to transport live animals for establishing nucleus farms overseas (e.g. In East and Southeast Asia). This can be expensive; energy is consuming, environmentally unfriendly, and carries important animal welfare and disease transmission concerns. One possible solution is to preserve and transports superior genetics in the form of preimplantation embryos (preferably pre-genotyped for sex and desirable production trait). To date, however, pig IVF and production (henceforth termed "IVP") has not been successfully implemented. The purpose of this thesis was to contribute to an ongoing effort to improve pig IVP through fundamental studies of porcine reproduction. Specifically, the work focussed on boar sperm production and on the human system (IVF clinic data) to provide clues as to the likely effects of embryo biopsy - an essential precursor to genotyping a preimplantation embryo as follows: The first aim was to produce a working classification system for boar sperm morphology and test the hypothesis that there are differences between high quality and poor quality boars. Some hitherto unreported features of sperm morphology were established as significantly different in the poor-quality boar seen group. The second was to assess the effects of stimulants (e.g. caffeine and adenosine) on capacitation and fertilization rates and ask whether there was a correlation between capacitation and fertilization. Here, the utility of caffeine was established, and correlations were observed between sperm morphology and capacitation rates. The third aim involved establishing whether novel markers of correct sperm chromatin packaging (CMA3 stain, nuclear organization, sperm aneuploidy) were indicative of reduced fertility in boars. Here a significant association between the poor-quality boars and level of CMA3 staining was observed indicating that this test may be implemented in the future as a means of identifying poor quality boars. No significant association with nuclear organization nor sperm aneuploidy was observed, however. Finally, attention turned to human IVF data to test the hypothesis that embryo biopsy adversely affected subsequent embryo development. Using state of the art time lapse imaging no evidence was found to indicate that biopsy had an adverse effect in humans suggesting that, if performed correctly, this may also be the case in pigs. Taken together, the results provide evidence for the potential of significant advances in pig IVP by adapting protocols already commonplace in humans. Indeed, during the project, and in part because of it, IVP success rates in the laboratory increased dramatically
