Kudos to BEEF magazine for the educational effort you've initiated over the last several months concerning bovine viral diarrhea (BVD) virus. Your magazine is doing a superb job of continuing the position statement to eradicate BVD that the Academy of Veterinary Consultants started in 2001.

As I travel across the country doing producer meetings, I've seen a marked increase in BVD awareness and how we can control and potentially eradicate the disease from the U.S. cattle population. Cattle producers are asking more and more hard questions about BVD after reading your articles. They're really understanding the disease, its process — and that cost-effective strategies exist to find persistently infected animals on the ranch and get rid of this costly disease.

I think we've entered a new realm in livestock-disease control in this country. You're a big part of the awareness that starts the process. Thanks for your efforts and leadership.

Please keep up the good work!
Bruce W. Hoffman, DVM
Animal Profiling International, Inc.
Manhattan, MT

Editor's Note: To learn more about BVD, its etiology and control, read our special, eight-page section, “Beating BVD,” after page 42 of this issue.

What is heterosis?

Your February article, “Crossbreeding With Composites,” page 22, related some misleading information.

“Dorland's Medical Dictionary” defines “heterosis,” as “the existence, in the first-generation hybrid, of greater vigor than is shown by either parent strain.”

And, “hybrid” as “an offspring of parents of different species.”

Your article claims “maximum heterosis is realized in the first cross of distinctly different parents.”

Hybrid vigor (heterosis) is hybrid breeding, which can't and doesn't come from crossbreeding of two animals of different breeds of the same specie. The two breeding animals must be of different species. There's no other way to have heterosis. Thus “distinctly different” parents don't result in hybrid vigor (heterosis) unless one parent is Brahman.

A classic example of hybrid vigor is the crossing of a horse and donkey, which are of different species. The result of mating a male donkey and female horse is a mule, which hybrid breeding makes larger and healthier than either parent.

There are three species of bovine in the U.S. — bison, Bos taurus (English) and Bos indicus (Zebu, known in the U.S. as Brahman). Crosses with the bison haven't been fruitful. The only successful way to develop hybrid vigor (heterosis) in the U.S. is to cross pureblood Brahman cattle to Bos taurus, unless you wish to use bison. This is the one and only true hybrid vigor in commercial cattle in the U.S. The preference is usually a female Bos indicus bred to a Bos taurus bull.
Richard N. Evans
American Brahman Breeders Ass'n
Beaumont, TX