Studies have indicated there is a difference in the desirability of cattle to flies, according to Missouri livestock specialist Eldon Cole in a recent online newsletter to producers. In fact, Arkansas researchers state the genetic resistance heritability is .58.

"That's considered a highly heritable trait and should respond nicely to selection," writes Mr. Cole. "The reasons for this genetic difference are still being researched but one feature is the hair density of the cattle. Those with more hairs per square inch, of course, will have more hair follicles that have glands that secrete chemicals that repel flies." It is yet unclear if the chemicals prevent the fly from feeding on the cattle or if they're actually distasteful, he adds.

The Arkansas researchers know that two proteins are present in more resistant cattle. In the future a simple blood test could identify more tolerant cattle.

"We do need to keep this type of research in perspective, as you may need to put selection pressure on other genetic traits before looking at fly control," cautions Mr. Cole. "However, as pesticide resistance develops and should organic/ natural beef production expand, this work will be helpful to those segments of the industry."