2/11/00

Contacts:
Max Rothschild, Animal Science, (515) 294-6202
Brian Meyer, Agriculture Information, (515) 294-0706

HUMAN FAT GENE LEADS IOWA STATE TO DISCOVERY ON LEAN PIGS

AMES, Iowa -- A gene that makes people eat more may make pigs leaner, according to Iowa State University researchers.

Many scientists have been studying the melanocortin-4 receptor (MC4R) gene in hopes of understanding more about the genetics of human obesity. The MC4R gene is now believed to play a significant role in regulating feeding behavior and body weight in humans and other mammals.

Iowa State animal scientists Max Rothschild, Kwan Suk Kim and Niels Larsen wondered whether different forms of MC4R might influence growth-related traits in pigs. They identified a naturally occurring mutation of the gene. Then, in collaboration with PIC International Group, a swine genetics company, they analyzed how this form of MC4R affected growth rate, backfat and feed consumption in more than 1,800 pigs from commercial pig-breeding lines.

"Pigs with one form of the MC4R mutation ate less, grew slower and were leaner," said Rothschild, a distinguished professor of animal science. "This result helps to confirm that MC4R is one of the genes involved in controlling economically important growth and performance traits in pigs."

Using this information, the researchers developed a genetic test to identify lines of pigs that satisfy pork producer and consumer preferences for leaner pork, Rothschild added. Different variations of MC4R also could speed up or slow down growth rates by increasing or suppressing the animals' appetites, he said.

Now that they know what the gene can do, the scientists want to better understand how it works. They plan further studies on the biology of the gene.

"This project is a good example of the power of comparative genomics, in which you study the genetics of one species in order to make discoveries in another," Rothschild said. "What we learn from the genetics of mice, humans or other species may be as important to farm animals as they are to humans."

The ISU-led research is featured on the cover of the February issue of Mammalian Genome, the scientific journal of the International Mammalian Genome Society. The cover shows a pair of mice with a major MC4R mutation and a pig from a commercial PIC line that has the naturally occurring mutation of the gene.

The ISU researchers have a patent pending on their work, which is licensed to PIC International Group. PIC helped to fund the project as well as actively participating in the research.

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