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Major Advances Seen for Swine Genomics

Swine genomics – the genetic mapping of the pig will provide the tools to build healthier, more productive pigs, according to a University of Illinois swine geneticist.

Swine genomics — the genetic mapping of the pig — will provide the tools to build healthier, more productive pigs, according to a University of Illinois swine geneticist.

Animal scientist Lawrence Schook made these predictions for swine genomics during the mid-September Leman Swine Conference in St. Paul, MN:

  • Disease resistance selection will be developed by 2005.

  • A quick diagnostic test to identify “at risk” animals for stress at shipment time will be available in a few years.

  • A food security system, driven by consumer interest in product traceability and producer interest in animal identification and traceback, will be implemented by 2005.

  • With more knowledge about immune expression, researchers will formulate new, non-antibiotic ways to manage health, shunning conventional antibiotics.

  • The pig genome will be sequenced by 2007, transforming herd health programs. Gene markers will be identified with specific genetic suppliers with breeding stock carrying natural resistance to infectious diseases.

Genome Mapping Progress

Low-cost diagnostics are on the way. Tools and information have been developed to permit application of genomics to improve the health and performance of pigs, explains Schook.

Swine genome mapping harkens back to 1994, when the first maps were published. They identified chromosomal regions that influence key traits affecting growth, body composition and reproductive and immune responses.

The pig genome is of similar size and complexity as the human genome, says Schook. Techniques are being developed to improve human-pig comparative maps. Using a Genome Positioning System, Schook says a map of the human genome can be used to help identify the genome of pigs.

The bacterial artificial chromosome (BAC) is a resource providing coverage of approximately 35% of the swine genome. These BAC resources have afforded development of high-resolution maps of specific chromosomal regions.

A coordinated international effort has been initiated to develop a porcine BAC map involving the Agriculture Department's Meat Animal Research Center in Clay Center, NE, the Roslin Institute in the United Kingdom and the University of Illinois.

High-density maps are being developed to help map difficult traits such as animal health, says Schook.

Besides the animal's genetic makeup that determines inherent resistance or susceptibility to disease, housing, stress of moving and nutrition also provide strong impact into the expression of genes, points out Schook. A process called microarray technology analyzes host-pathogen interactions to determine the cause of change in the cellular state of the pig.

Application Challenges

Two challenges facing the use of genomic information to improve pig health are being addressed. First, the need for content information is being studied experimentally and on the farm. Second, genetic markers have been identified to address the need for developing fast, low-cost technology platforms to permit the broad utilization of genomic data, he says.

Recently, the National Institutes of Health have added the pig to the list of high-priority animals for complete genome sequencing.

“When finished, this sequencing will permit rapid identification of genes to create new screening tools for the development of new drugs and medicines that promote animal health and performance,” concludes Schook.

Gene Mapping Project Funded

Three University of Illinois scientists were awarded $3 million in a five-year project to create comprehensive genome maps of the pig and cow.

“It took a billion dollars to sequence the human genome. The National Institutes of Health had this huge investment in technology, people and equipment and they finished early,” says Lawrence Schook, University of Illinois animal geneticist. “So they decided to use the remainder of the resources to sequence the genome of other species.”

The research funded by the U.S. Department of Agriculture will be the first step toward sequencing the pig and cow genomes.

For a decade, Schook and fellow animal science geneticists Jonathon Beever and Harris Lewin have been studying genes for disease resistance, lactation and growth. Schook and Beever work on pigs and Lewin studies cows.

Cows, pigs and humans all share something in common, a placenta, but also have enough differences to make contrasting easy. “Having the gene maps and sequences of other species, particularly other mammals, will help us better understand the human genome,” says Schook.

Small variances in DNA coding appear to account for the differences between pigs, cows and humans. By looking at the differences and similarities, scientists believe they can better understand how all three species evolved.