New Test Could Help Breed Edema-Resistant Pigs

By Linda McGraw
July 6, 1999

Hog farmers may be able to rear pigs with a natural ability to resist edema disease caused by an intestinal E. coli bacteria. That’s welcome news for producers who lose money when young pigs get sick from a type of E. coli called F18.

U.S. Department of Agriculture researchers in Ames, Iowa, and the Pig Improvement Company (PIC) of Franklin, Kentucky, cooperatively developed a DNA-based test to identify pigs genetically resistant to the F18 E. coli strain that causes edema. Rapid growth of F18 E. coli in the 3- to 14-week-old pig’s small intestine after weaning leads to edema disease, characterized by a excessive build-up of body fluids. The F18 strain doesn’t cause disease in humans.

“This is a natural way of breeding healthier, more disease resistant pigs. For producers, this strategy is a better alternative than increasing use of antibiotics in animals. The cost of vaccines and antibiotics cuts into producers profits,” said Agricultural Research Service Administrator Floyd Horn. ARS is USDA’s chief scientific research agency.

ARS microbiologist Julia F. Ridpath at the National Animal Disease Center in Ames, Iowa, and Brad Bosworth, who was an ARS veterinarian and is now a group veterinary scientist with PIC, discovered resistance and susceptibility to F18 is linked to a specific gene. A Swiss scientist, Peter Voegeli, concurrently made the same discovery.

Ridpath and Bosworth have validated their test on more than 500 pigs.

“Pigs that are resistant to edema disease lack intestinal receptors. The lack of receptors makes it impossible for this bacteria to stick or attach to the intestinal wall,” said Bosworth. The scientists also identified another way to reduce the problems caused by the F18 E. coli bacteria: feed weaned pigs more animal protein in place of soybean meal. This tactic prevents the bacteria from taking hold in the susceptible pig.

The death rate among pigs with full-blown edema disease is about 25 percent.

ARS and the Biotechnology Research and Development Consortium (BRDC) in Peoria, Illinois, hold a patent on the test. PIC has a worldwide exclusive license for the commercial use of the technology except in Switzerland.

A story about the research appears in the July issue of ARS' Agricultural Research magazine and on the web at:

/is/AR/archive/jul99/pigs0799.htm

Scientific contact: Julia Ridpath, ARS Enteric Diseases and Food Research, National Animal Disease Center, P.O. Box 70, Ames, Iowa 50010; phone (515) 663-7372, fax (515) 663-7458, jridpath@nadc.ars.usda.gov.