Cryoconservation of animal genetic resources
"[2] Genetic materials that are typically cryogenically preserved include sperm, oocytes, embryos and somatic cells.
Gene banks must maintain a precise database and make information and genetic resources accessible to properly facilitate cryoconservation.
However, cryoconservation can be an expensive strategy and requires long term hygienic and economic commitment for germplasms to remain viable.
[3][13][14] Cryoconservation is the process of freezing cells and tissues using liquid nitrogen to achieve extreme low temperatures with the intent of using the preserved sample to prevent the loss of genetic diversity.
[15] Semen, embryos, oocytes, somatic cells, nuclear DNA, and other types of biomaterial such as blood and serum can be stored using cryopreservation, in order to preserve genetic materials.
[3][4] The primary benefit of cryoconservation is the ability to save germplasms for extended periods of time, therefore maintaining the genetic diversity of a species or breed.
[17] Cryoconservation is an indispensable tool in the storage of genetic material of animal origin and will continue to be useful for the conservation of livestock into the future.
[18] The loss of regional livestock diversity could increase instability, decreases future possibilities and challenge production systems.
[9] Moreover, the maintenance of indigenous breeds can aid in the preservation of traditional lifestyles and livelihoods, even providing income through cultural tourism.
[20] Indigenous livestock often have beneficial traits related to adaptation to local climate and diseases that can be incorporated into major breeds through cryoconservation practices.
[21] Cryoconservation is a favorable strategy because it allows germplasms to be stored for extended periods of time in a small confined area.
An additional benefit of cryoconservation is the ability to preserve the biological material of both maternal and paternal cells and maintain viability over extended periods of time.
[4] With proper preparation of collecting and maintaining genetic material, this method is very beneficial for the conservation of rare and endangered livestock.
[35] Somatic cells are an additional resource which can be retrieved for gene banking, particularly in the cases of emergency wherein gametes cannot be collected or stored.
Due to osmosis, the water from the cells enters the medium to keep the concentrations of sugars, salts, and cryoprotectant equal.
The vitrification method applies a selected medium which has a higher concentration of solute so the water will leave the cells via osmosis.
Additionally, a perimeter fence is used to prevent potential threats that could cause contamination to germplasms, such as unauthorized personnel or unwanted animals, from entering the facilities.
When interaction with outside objects, such as feed trucks or veterinary personnel, is necessary, complete sanitation is required to decrease the risk of contamination.
As the process of collecting germplasm may take several days, the animal may become stressed causing a lower quality of genetic material to be obtained.
For example, artificial insemination is more difficult in sheep than cattle, goats, pigs, or horses due to posterior folds in the cervix of ovines.
Pig embryos are the most difficult to freeze, thaw, and utilize produce live offspring due to their sensitivity to chilling and high lipid content.
Livestock are traditionally a private good; in order to obtain ownership of genetic materials, gene banks have several strategies that they can deploy.
An example of the use of cryoconservation to prevent the extinction of a livestock breed is the case of the Hungarian Grey cattle, or Magyar Szürke.
[44] The Hungarian government launched a project to preserve the breed, as it possesses valuable traits, such as stamina, calving ease, disease resistance, and easy adaptation to a variety of climates.
[45] Gaur, also known as the Indian bison, is the heaviest and most powerful of all wild cattle native to South and Southeast Asia.
[46] Male and female gaur both have distinctive humps between the head and shoulders, a dorsal ridge, prominent horns, and a dewlap which extends to the front legs.
[47] The gaur population experienced a drastic decline of about 90% between the 1960s and 1990s due to poaching, commercial hunting, shrinking habitat, and the spreading of disease.
[48][49] According to the International Union for Conservation of Nature's Red List, the gaur is a vulnerable species due to its declining population in Southeast Asia.
[46] The American Association of Zoos and Aquariums, Integrated Conservation Research (ICR), and Advanced Cell Technology have made efforts to use cryopreserved specimens of the gaur through artificial insemination, embryo transfer, and cloning, respectively.
[47] Cryopreservation is also commonly employed in biomedical research to archive and distribute genetically engineered mice (Mus musculus).
