European researchers have found no evidence that Bovine Spongiform Encephalopathy (BSE, often called "mad cow disease") can not be transmitted other than by the two known methods, ingesting contaminated feed and directly from dam to calf. Other studies show that embryos from infected cattle neither develop nor transmit the disease, so there is no reason for regulations prohibiting shipment of such embryos. American researchers have developed a rapid, on-site, easily-interpreted test for BSE. Such a test would allow screening at the slaughter facility to ensure that infected products do not enter the human food supply. Finally, a Harvard/USDA study shows that existing protection systems have helped keep BSE out of the U. S. and would prevent its spread if it ever got in. Remember, there have never been any BSE-contaminated materials or infected animals found in the U. S.
CALVING PROBLEMS, IS IT THE CALF OR THE DAM?
USDA workers studied genetic factors affecting dystocia (the two-bit term for calving difficulty) in first-calf two-year-old heifers. Heritability of direct effects of the calf were found to be about twice as large as maternal genetic effects. By far the most important calf effect was birth weight. Also, calf and maternal effects were negatively related. That is, as you improve calving ease through calf genetic effects you tend to adversely affect maternal genetic calving-ease factors. This has been found in other work. It was concluded that meaningful progress in reducing calving difficulty will likely require reduced birth weights.
COMPOSITES - WHAT ARE THEY?
There is a lot of interest today in composite breeds of cattle. Are composite breeds something new? What is a composite? The most commonly accepted definition of composite is "a population created from at least two existing breeds, designed to retain heterosis in future generations, and maintained like a purebred". For many years, breeds have been created by combining existing breeds and then maintaining them as a breed. Up to now, there has been little if any effort to maintain heterosis in such breeds. That is probably the only new thing about the new composites. Some say new composites are bred with a purpose, to combine the desirable genetic qualities of each breed. It is said that Mark Twain used to tell a story about "a mighty good dog, a composite, not a mongrel". According to Twain a composite was "a dog made up of all the valuable qualities; a mongrel is made up of the rif-raf that's left over". When you combine breeds and then inter-mate you do get the good parts. But you also get the bad parts. The new combination may be superior, but if so it's not because undesirable features were eliminated. The new combination is just a better package. The only way to get the good features without the bad (called complementarity) is with a well-planned terminal cross. And a terminal cross can not reproduce itself, it must be re-created every time.
2002 NCBA/IRM REDBOOKS STILL AVAILABLE
The pocket diary/record keeper/management reference known as the Red Book is available from the National Cattlemen's Beef Association, (303) 694-0305. Single copies cost $4.50.
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