In vitro embryo production in animal breeding: Enhancing oocyte quality from peri-pubertal donors to promote biosecure and sustainable food production

The world population will increase from 7 to 9 billion in the next 30 years. Consumption of meat (over half of which comes from pigs and cattle) and milk (nearly all from cattle) will also rise by 20% per person. This will place an intolerable demand on food producers globally who are charged with generating more meat and milk from fewer animals, in less time. Livestock production also contributes 18% of global warming. Using genetic selection to improve livestock productivity offers the most sustainable means to match increased global demand for animal products and to mitigate harmful effects to the environment. The UK leads the world in farm-animal genetics, but the pace at which genetic change must occur in future represents a challenge. The use of advanced reproductive technologies such as in vitro fertilised (IVF) embryos offers several benefits in this regard. Many IVF embryos can be generated from a small number of elite females allowing us to be more selective. Genetic traits can also be screened in IVF embryos just a few days after fertilisation. This speeds up the time to selection, prevents the birth of unwanted animals and has the added advantage of facilitating bio-banking of genetically precious stock, together with low-cost, high-welfare and biosecure international transportation. IVF embryos from young (peri-pubertal) donors can lead to a greater increase in the rate of genetic improvement by reducing the time to selection even further. The ultimate aim of this project, therefore, is to make pig and cattle IVF work better from mothers that are as young as possible. Pig and cattle embryos are also good models for studying human IVF. By developing a better understanding of the biological processes that occur during IVF, particularly for the peri-pubertal donor, we aim to improve significantly the overall efficiency of this procedure, thereby making it the method of choice for genetic selection in future. We believe that we can improve the process in both species by focussing on reducing the level of gross genetic abnormalities (i.e. extra or missing chromosomes) in the embryo which is linked to energy metabolism by numerous small structures within the cell called mitochondria. Our central question therefore is can we improve the quality of the embryo produced by improving the oocyte (egg) maturation process? In cows, we will also investigate milder therapeutic regimes used to stimulate ovaries (similar to human IVF) in the hope that this will also improve egg and embryo quality, together with dietary regimes designed to do the same. This should reduce levels of gross genomic imbalance, metabolic problems and stress in our embryos, thereby increasing their developmental potential. Our second question is whether this actually leads to "on-farm" improvements in live-birth rates following embryo transfer. By combining our new regimes of IVF with screening and removal of embryos containing mitochondrial and chromosomal abnormalities we aim to establish this. The academic and industry partners in this LINK proposal have enjoyed a successful track-record of collaboration in developing pig and cattle IVF in recent years. The current application will witness a step-change in improvements to this technology as we address a fundamental aspect of developmental biology associated with metabolism and chromosome behaviour during IVF. Our industry partners will work alongside us to collect eggs, undertake dietary studies and large-scale on farm embryo transfers to demonstrate improvements in live-birth rates. The unique "selling point" of this application, therefore, is the novel combination of approaches, academics and industrialists that will ensure success of the project all the way from research lab to farm.