Public Release: 

Genomics research promises to make hogs less piggy

Purdue University

Animal scientist William Muir displays an automated gene sequencing machine in a laboratory at Purdue University. (Purdue Department of Agricultural Communications photo by Tom Campbell.)

A publication-quality photograph is available at and at Photo ID: Muir.hoggenome

WEST LAFAYETTE, Ind. -- "Boss hawg" isn't just a term, but an actuality in the nation's hog lots. In each group of hogs, there will be one or two who will bite and push and make sure they get the most food.

Purdue University researchers believe that by locating the genes for aggressive behavior in hogs, they can make the boss hog into a more sensitive soul, and less ... well, piggy.

This isn't research aimed at creating hog harmony, but increasing production. William Muir, professor of animal science and director of Purdue's genome sequencing facility, says keeping hogs happy could increase their lean growth by as much as 25 percent.

Allan Schinckel, professor of animal science and hog genetics, says scientists are well aware of the negative effects that aggressive behavior can have on hog production.

"The more pigs you have in a pen, the slower their growth rate due to stress and aggression," he says. "Even having them together for 48 hours slows the growth rate of the pigs for two weeks."

Muir and Schinckel say increasing pork production by just 20 percent in the United States would mean an additional $2 billion annually for the nation's pork producers. Using conservative numbers, that could mean an additional $200 million for Hoosier hog farmers each year.

Increasing lean growth 25 percent without increasing feed sounds like hogwash in this day and age of tightly controlled breeding programs. But by using genomics to identify genes that influence behavior, Muir says such a gain is within reach.

The prediction is based on Muir's research into aggressive behavior in chickens. In that research, he detected that competition for food had a significant effect on animal survival and production. Through that work, he discovered major genes for behavior in vertebrates.

"These genes aren't used in hog breeding programs," Muir says. "They are concerned about behavior in breeding programs, but breeders don't have a way of precisely targeting it."

When Muir applied his techniques to hogs, he found that in a typical hog facility raising eight pigs per pen, there was an overall deficiency in lean growth because the hogs were fighting for food. Some of the dominant pigs "hog the trough" as it were, and eat more than they need. "That's just nutrients going down the drain," Muir says.

The less aggressive hogs, on the other hand, don't get the nutrients they need and don't grow to their potential.

"Another reason that the hogs don't grow to their potential is that when they are fighting, they produce lots of heat, which requires energy to produce," Muir says.

By using genomics techniques, Muir says he believes he can alter this behavior enough to see the 20 percent to 25 percent growth increase. "We've been able to use this method in quail to achieve more than a 200 percent gain in growth," he says. "We know that this isn't just pie in the sky."

By using a genomics technique called a "genome scan," Muir hopes to be able to find genes in hogs that also influence behavior.

"Now we can use either marker-assisted selection to integrate those genes into breeding nucleuses to create less aggressive hogs, or we can clone the genes by using fine gene mapping techniques," he says. "Then, we can directly move those genes into hog populations."

Muir points out that this increase in growth would occur with no additional feed or vitamins.

"Here we're talking about something for nothing," he says. "This is a win-win-win situation. The farmers win because they get more output with no additional input. The animals win because they are less stressed, and society wins because we all would like to see our animals treated in a way that improves their well-being."


Writer: Steve Tally, (765) 494-9809;

Related Web sites:
Purdue Genomics backgrounder page:
Muir's professional homepage:
Schinckel's professional homepage:

Sources: William Muir, (765) 494-8032;
Allan Schinckel, (765) 494-4836;


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