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Centre for Genetic
Improvement of Livestock Family Planning ... For Fish |
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By tracing the family trees of farmed fish, a University of Guelph research group is hoping to give producers improved breeding stock ... and provide consumers with the best product possible. Research teams from the Centre for Genetic Improvement of Livestock (CGIL) and the Department of Zoology are collaborating to examine the genetic relationships within schools of rainbow trout. They're using DNA technology to sort the fish into families, to select a strong and progressive parent stock without the fear of inbreeding. Developing a New Strain The researchers are defining how much impact genetic selection can have on improving the physical traits of rainbow trout. Using DNA analysis, they'll develop a new strain of rainbow trout - one that grows more rapidly, reaches sexual maturity at a later age, and spawns in the spring rather than the fall. Early spawning is of particular interest because it would provide producers with a second annual harvest and consumers with a more consistent source of fresh Ontario fish. Without looking at the genetic make-up of the fish, selecting breeding stock can be a problem. "Looking down into a tank of hundreds or thousands of rainbow trout, it's impossible to know who's who," says researcher Laura McKay, one of the project's leaders. "Genetic analysis reduces that problem and helps us avoid breeding brother to sister." Rainbow trout are quickly becoming a major factor in the agricultural landscape of Ontario. Farms that can produce hundreds of thousands of individual fish each year are appearing throughout the southern part of the province, busily accommodating the expanding retail fish market. Like any agricultural commodity, fish producers continually strive for improved parent stock and better management practices. Progress toward faster growing, more efficient animals can, however, be particularly difficult in aquaculture. With thousands of virtually identical fish intermingling in pool-sized tanks, it's difficult to identify individuals with superior genetics and isolate individuals that show extraordinary physical properties. Then, even if this feat is accomplished, there's no guarantee the parents selected aren't brother and sister...a single mating will typically produce 3,000 to 5,000 fry, so accidentally breeding siblings is an easy mistake to make. McKay says genetic technologies may be the key to making the best possible choices of breeding pairs. Using several tanks, the CGIL research team produced a series of pooled lots of rainbow trout. Each group was started with three to four unrelated females and three to four unrelated males. As the fry grew and developed, fin clippings were collected, the DNA extracted and then analyzed by the Zoology team. The results of the DNA tests enabled the researchers to trace offspring back to their parents. This information allows young fish with desirable characteristics to be selected and bred with unrelated counterparts, avoiding the potential complications of inbreeding. "Genetic technologies can provide us with an edge over traditional parent selection techniques," says McKay. "With faster development of new trout strains, we can pass those advantages on to the consumer as quickly as possible." The research team consists of McKay, Prof. Ian McMillan and graduate student Cheryl Quinton, CGIL, and Prof. Roy Danzmann, Prof. Moira Ferguson, and graduate student Gavin McDonald, Zoology. This research is sponsored by the Ontario Ministry of Agriculture, Food, and Rural Affairs. |
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