Genetic Markers May Show Way To Better Poultry

FAYETTEVILLE - Genetic markers can help poultry breeders identify hidden characteristics and guide them on the path to producing healthier, more desirable birds.

Ron Okimoto, University of Arkansas poultry scientist, is looking for those markers and determining what they mean. He is also studying how their corresponding genes interact with the rest of the genetic code to determine what color a chicken will be, how efficiently it uses feed and how well it resists diseases.

"Knowing more about how genes interact and control characteristics will give breeders more accurate information to select birds for conventional breeding," Okimoto said.

He's identifying markers that reveal the presence and location of alleles - genetic variants that account for differences in the appearance and development of offspring.

"All living things have two copies of their genes," Okimoto said. "Sometimes, one copy may vary from the other in one or more locations on the gene. These are called alleles, and a gene may have many of them. Nearly every gene we've looked at has alleles. Genetic variation is the reason we all do not look like clones."

One of the traits he's studying is pigmentation. "Pigments that affect feather color also affect coloration in the flesh," he said. "Poultry companies want to avoid discoloration of the meat caused by pigments. There is nothing wrong with it except that consumers don't want discoloration in white meat.

"So poultry companies want to breed chickens with less pigmentation. The problem is that broilers' feathers are all white, so they hide pigmentation problems," he said.

Okimoto said the only conventional way to find undesirable pigmentation in broilers is to breed them to colored chickens and see how the crossbreeding affects feather color. This process costs more time and money than a commercial breeder wants to spend to correct a purely aesthetic problem.

"Now we can find the problem with a simple blood test," he said.

Research groups like Okimoto's have been identifying markers for genetic variations for a decade, but no one has used them as a tool for selecting chickens for breeding. "We've identified the genes that cause these variations and we've got the markers that tell us when they're present," he said. "Now we're taking it to the next step, using them to select birds for breeding, to see if they work the way we expect them to."

In practice, poultry companies will select breeders for whole range of characteristics, and pigmentation will probably not be the most important one. A bird with undesirable pigmentation may be selected because it has have superior growth rate or resistance to ascites. (Ascites is a pulmonary hypertension syndrome that afflicts some broilers because their fast growth rate can outpace their cardio-pulmonary system.)

Genetic markers can help breeders more accurately determine the genetic potential of a bird and allow them to make more informed selection decisions, Okimoto said.

"One of the main things this work is going to do is help us get a handle on quantitative genetics," he said. "It'll help us understand how these genes interact with each other and give us a means to measure them and develop more accurate genetic models.

"The more we know about what's happening on the genetic level, the more we can help breeders develop better birds."