|
| From the Publisher's Desk |
| Kudos |
| Pork Chops |
| Recipe |
| E-Stories |
Genomics - The Future is Now
Phenomenal reductions in cost has been a big factor in improving the ability of animal breeders to use genetic markers for selecting the best bloodstock and predicting outcomes more accurately, say scientists who discussed advances in genomics during the 2012 Banff Pork Seminar.
Graham Plastow from the University of Alberta, Jack Dekkers of the Iowa State University and Joan Lunney from the United States Department of Agriculture in Maryland each described work that has been done in genomics and its relevance in improving the animals available for breeding and commercial production.
Selective breeding has considerably improved the pig in recent years, including its ability to convert feed and to resist disease, said Plastow.
However, more improvement is still needed to create a pig that will remain relevant as the demand grows for environmentally sustainable production of food animals, he said.
"We believe that, with genomics, we'll be able to do even better," said Plastow.
Genomics provides the tool for identifying genetic traits that are difficult to measure. In fact, the more difficult it is to measure certain traits, the more relevant it is to be able to identify the genetic markers responsible for those traits, said Plastow.
Earlier on, the costs related to gathering the necessary data were extremely prohibitive, he said. Technological advancements have reduced costs and the time required for DNA sequencing have come down to levels where it is economically viable to sample DNA from large numbers of animals and identify the genetic information necessary to breed for desired characteristics including reproductive prowess, feed gain and conversion and disease resistance.
"What really we're saying is, there is no roadblock at all now to having the material to look at the DNA, the genomics of an animal. The roadblock is getting the right phenotypic information to drive the technology," he said.
While genotype refers to the genetic makeup of an individual, the phenotype refers to its visible and measurable characteristics, such as how and where it packs on fat and muscle.
In addressing the implications of genomic programs, Dekkers described genomics as the black box of quantitative genetics.
"We know we want to improve all kinds of traits in our livestock animals. We can measure the phenotype and we can analyze that statistically, and that works very well (with) lots of genetic improvement.
"So, then we can open some of that black box and find some genes or markers that are associated with the traits and use that as genotypes to make better selection decisions," he said.
The phenotypic data is still relevant, because many of the traits being examined are affected by a large number of genes, said Dekkers. However, there is an advantage to using genetic marker data. For example, when looking at litter size, the breeder must determine which sires will produce the most prolific females, he said. Using genomics allows the breeder to assess litter size in both sexes, something that cannot be done using phenotype alone, said Dekkers.
"Without genomics, all you have is pedigree."
Lunney said she and the people she works with have been working intensely to find genetic information that would allow breeders to select for resistance to PRRS (porcine respiratory and reproductive syndrome).
"We really have a series of things that go on in an immune response. As complex as it may be, we are beginning to have the tools to really get into and understand this complexity and apply it in different situations," said Lunney.
"We know that there are immune traits that . . . can be analyzed. Now, we should be able, hopefully, to improve health traits and go into the commercial pig genetics box and get some more disease data."
Steve Bishop, who is performing related research at the Roslin Institute in the United Kingdom, said during the panel session that, while PRRS is the obvious disease for this type of research, there is a question about whether there are other diseases that may justify the same level of effort.
The discussion hasn't even begun yet on what the implications are for other traits, beyond health issues, said session chair Bob Kemp, a geneticist with Genesus Genetics. •
— By Brenda Kossowan
Cutlines :
Joan Lunney, United States Department of Agriculture based in Maryland.
Jack Dekkers of the Iowa State University