Why did we fund this project?
This award aims to reduce the number of chickens maintained as permanent breeding flocks for research by optimising cryopreservation procedures for the most commonly used breeds at the Roslin Institute.
Cryopreservation is used to preserve samples of cells and tissue at low temperatures, allowing long-term preservation. In mammalian research, embryos and germ cells can be cryopreserved maintaining the genetics of the model and avoiding the need to continually maintain the animals “on the shelf” when they are currently not required for experimental purposes. However, these cryopreservation methods do not work for avian reproductive cells so flocks of chickens must be raised and maintained indefinitely to provide research animals. Dr Mike McGrew has developed a new technology where reproductive cells from chickens can be frozen and transferred into eggs from a sterile chicken line. Chickens hatched using this protocol lay eggs of the transferred chicken breed.
With NC3Rs funding, Mike will optimise cryopreservation for three research chicken breeds using the new protocol by transferring multiple genotypes into sterile eggs. He will then confirm the genotype transmission rate and determine the number of birds needed for a genetically diverse flock to be reconstituted from frozen material. The flock’s health and virility will be validated and the first research poultry biobank created.
Our ability to cryopreserve avian species is extremely limited leading to research flocks of chicken to be raised indefinitely as permanent breeding flocks. A validated protocol for the cryopreservation for research chicken will drastically reduce or eliminate the numbers of chicken kept in research institutes, greatly reducing maintenance costs and provide increased biosecurity against pathogen outbreaks, such as avian influenza, which could result in the destruction of these genetic resources and in the end endanger sustainable food production.
The overall goal of this project is to demonstrate the reestablishment of a research chicken flock from frozen material; something to date that has not been demonstrated for a poultry species. In this project, we make use our newly developed sterile surrogate host chicken which permits 100% transmission of donor genetic material. We have also recently developed a protocol to directly freeze embryonic germ cell material eliminating the need to culture reproductive tissue before cryopreservation. We will first optimise cryopreservation procedures for three research chicken lines currently maintained at the Roslin Institute. We will next directly measure the genotype transmission rates from single sterile surrogate host chicken carrying multiple donor genotypes. This result will define our efficiencies and bird numbers needed for re-establishing a chicken flock. Finally, we will demonstrate the reconstitution of a research line of chickens followed by monitoring the fertility and health of the re-established flock. With this information, we will be able to confidently biobank and reconstitute research poultry breeds.