Concentration of Global Poultry Genetic Resources
By Treena Hein
Concentration of Global Poultry Genetic Resources
By Treena Hein
Concern over the diminishing worldwide genetic resources has reached
new heights with the recent announcement of an alliance between poultry
breeders Cobb-Vantress and Hendrix Genetics.
| An international research team has analyzed the genetic lines of commercial chickens and found that they are missing more than half of the genetic diversity native to the species. Research team member and Purdue University professor Bill Muir has stated that this finding indicates it’s important to preserve
Non-commercial breeds and wild birds for the purpose of safeguarding genetic diversity.
Concern over the diminishing worldwide genetic resources has reached new heights with the recent announcement of an alliance between poultry breeders Cobb-Vantress and Hendrix Genetics.
This marks the beginning of a worrying new reality for the global poultry industry, because all of the world’s turkey-breeding and egg-laying stock, and most broiler stock, now originates from this new alliance and one other major corporation: German-based EW Group, which owns Aviagen (Ross, Arbor-Acres, Lohmann-Indian River meat chicken brands, plus BUT and Nicholas Turkeys), Lohmann, HyLine and H&N International layers. The only two “independent” breeders are Hubbard broilers (France) and the very small layer breeder Babolna-Tetra (Hungary), which only supplies local markets. Experts agree there is little chance any new breeding start-up companies will be created.
“The industrial genetic concentration is really extreme,” observes Dr. Fred Silversides. “There were 300 Canadian breeders in the 1940s, and now we have none.” Silversides is an Agriculture and Agri-Foods Canada (AAFC) researcher at the Avian Genetic Resource Centre (AGRC), a partnership between University of British Columbia (UBC) and AAFC, located at the Pacific Agricultural Research Centre in Agassiz, B.C.
|Extreme Concentration – Dr. Fred Silversides, an Agriculture and Agri-Foods Canada (AAFC) researcher at the Avian Genetic Resource Centre (AGRC) in B.C., says that in the last 65 years, the world has gone from 300 breeders down to two and that, as geneticists retire or pass away, genetic diversity is further compromised.
The world’s white-egg-laying breed contains significant amounts of just one line of birds says Silversides. Turkey genetics are even less diverse, while brown egg layers and broilers both have a somewhat more diverse background that is based on three or four lines instead of one.
Unfortunately, the other major cause of disappearing genetic diversity besides industry consolidation is also gaining ground. “As researchers retire, the chickens they worked with get thrown out,” says Silversides. “The lines get discarded because the only way of keeping the lines is to keep the chickens and that’s expensive. There’s so little genetic diversity and it’s being eliminated so quickly.”
Why genetic diversity matters
Lack of genetic variation, simply put, equals greater risk. Members of a population that shares the same set of genes can all be overcome by a disease, but if a population’s members contain different gene sets, there is a chance some will survive.
A small genetic pool is also risky because it leaves little room for the industry to address any changes in consumer preferences, says Silversides. He is also gravely concerned that the current worldwide economic downturn may lead to even lower genetic variation if one of the two current players is absorbed or eliminated.
Cryopreservation is one way to save the remaining diversity. This technique involves freezing tissue for storage in such as way that it can be successfully thawed and used in breeding. “However,” says Silversides, “the freezing techniques we have are really limited. The problem with poultry is that there isn’t a good way of freezing the material to achieve good fertility. Mammalian cryopreservation techniques don’t work for poultry eggs and embryos, and only work poorly for semen.”
That’s why over the last four years, Silversides, Dr. Yonghong Song and other colleagues have been experimenting with cryopreservation methods that work. They have successfully transplanted ovarian and testicular tissue between newly hatched chicks, and are working on transplanting frozen and thawed tissue. Dr. Song is also conducting experiments to transplant ovaries between different species of ducks. Silversides says, “Successful interspecies breeding in this manner may become critically necessary in future.”
AGRC scientist and UBC avian science professor Dr. Kimberly Cheng says that because of the Silversides/Song techniques, genetic materials from most of the chicken lines breeds from the Nova Scotia Agricultural College, the Universities of Alberta and Saskatchewan and the AAFC Agassiz Research Centre are now kept in the AGRC deep freeze for preservation.
The AGRC also houses nine lines of chickens and nine lines of Japanese quail – currently 3,500 birds – that are being carefully bred, pedigreed and studied. “Collectively, these lines build a living genetic library consisting of a wide variety of genetic mutations,” says Cheng. “The AGRC’s genetic resources allow scientists the world over to study how genome affects size and meat quality, disease resistance, how well particular breeds could adapt to farm facilities and how we can help industry improve housing environments and breeding practices.”
Genome research on birds may also lead to further advances in human health. Cheng’s research from almost three decades ago recently helped successfully reverse congenital blindness. In 1980, Cheng discovered a gene mutation in a line of Rhode Island Red (RIR) chickens that were blind at hatching. (Genetic material from these birds is still housed at AGRC.) The gene was sequenced by scientists at the University of Florida and found to be the same as a human gene that causes a form of congenital blindness called Leber’s Congenital Amaurosis. Last April, a team of researchers from the University of Pennsylvania used the research and techniques to partially restore sight to three human patients.
Other poultry genetics research
An international research team has analyzed the genetic lines of commercial chickens and found that they are missing more than half of the genetic diversity native to the species. Research team member and Purdue University professor Bill Muir has stated that this finding indicates it’s important to preserve non-commercial breeds and wild birds for the purpose of safeguarding genetic diversity. He also believes interbreeding additional species with commercial lines might help protect the industry.
Muir also is project co-leader in a current $10 million international effort to test a breeding strategy called whole-genome selection that could be used to improve the accuracy and efficiency of breeding methods. Companies may be able to use this technique to select for important parts of the DNA of donor birds from standard or ancestral breeds and integrate those into commercial lines without having to also insert DNA that causes unwanted traits.
Both Cobb Vantress Inc. and Aviagen provided comments on issues related to genetic diversity preservation; these comments are presented in shortened form here.
In terms of how much genetic “backup” each company possesses in case of disease outbreak or a similar situation, Brian Cosgriff, director of marketing for Cobb Vantress Inc., says, “As Cobb continues to increase the number of pedigree lines in its gene pool, we increase the likelihood of finding a line or lines with good resistance to any specific disease which may increase in importance…Cobb currently supports several projects designed to identify genes related to disease resistance.” He adds, “As backup to internal production, Cobb goes to great lengths to carefully divide product pedigree lines among multiple pedigree farms located in the U.S., and also on a new pedigree farm in the Netherlands….As added backup to the duplication of pedigree birds, great grandparents…are also strategically isolated and placed in flocks located in the several facilities within the U.S., and also on farms in the U.K., Brazil and Australia.”
Dave Burnham, head of Global Marketing at Aviagen says, “In addition to lines being selected for ongoing genetic improvement or change, Aviagen maintains two distinct sets of pure lines which are not being subjected to genetic selection. The first of these groups was established in 1972 and the latter group in 1996.” He adds, “Aviagen maintains and improves distinct duplicate populations of lines in different continents in order to ensure security, both in terms of genetic integrity and in terms of product supply.”
When asked to describe how the need for preservation of genetic diversity fares in importance compared with breeding direction priorities, Cosgriff stated, “We have a good balance between our breeding program, which has specific traits for selection, and those which maintain good genetic diversity. In the last eight years alone, we have purchased over 30 new genetic lines of chickens which add to the significant existing library of lines already in house.” He adds, “We actively support research with coloured bird and indigenous chickens which offers the possibility of crossing these lines with modern commercial white chickens to fit opportunities in the future.”
Burnham says, “Aviagen manages a large range of commercial and experimental pure-lines with varied genetic backgrounds, characteristics and improvement objectives. Some of these are constituents of long-standing products and are based on continuing genetic improvements in large populations under selection, while others are experimental lines displaying novel combinations of traits that address new or emerging markets.”
With regard to how genomics can serve to perhaps reduce the importance and need for having preserved genetic diversity resources, Cosgriff says, “Genomic analyses of genetic differences among our lines…is already helping Cobb identify the combinations of lines which are most diverse from each other as potential for new product crosses in the future….Technology like the utilization of gene markers, is now just developing to the stage where it offers the feasibility to identify useful genetic variation for incorporation into current lines and help maintain genetic diversity for the future.” Burnham adds, “The use of genomics will be a useful tool to improve the accuracy of selection and will allow us to manage our genetic resources even more effectively.” n