Federal regulations on selenium have changed.
As previous discussions here have noted, it is not only a necessary trace element that is lacking in some areas. It can also be poisonous.
As if reflecting this confusing situation, in 1987 federal regulations established the amount of selenium allowed as a supplement in animal feeds.
In September, 1993, the FDA anounced that selenium supplements were no longer allowed.
In September, 1994, legislation was passed that suspended that stay until December, 1995. A second action, which was included in the Federal Crop Insurance Reform Act signed on Oct. 14, 1994, states that the FDA shall not implement or enforce the stay unless the Commissioner of the FDA finds that selenium supplementation at 0.3 ppm in complete diets is not essential to maintain animal health, is not safe to animals consuming the additive or to humans consuming edible portions of selenium-supplemented animals, is not effective to promote normal growth and reproduction, and that the manufacture and use of supplemental selenium cannot be reasonably controlled by adherence to current good manufacturing practice requirements.
As a result of these actions, the FDA's stay of the 1987 amendments is no longer in effect. Animal feeds may be supplemented with the levels of selenium stated in the 1987 ammendments.
The maximum supplementation level in complete rations for chickens, swine, turkeys, sheep, cattle and ducks is 0.3 ppm (parts per million). The limits for feed supplements for limit feeding and in salt-mineral mixtures for free-choice feeding for sheep and beef cattle return to those provided for by the 1987 amendments.
In addition, the osmotic selenium bolus, approved for use in beef and dairy cattle in 1989, can also be used as a source of selenium. Thge bolus provides 3 mg of selenium per day.
The legislative actions also remove the requirement that premix manufacturers analyze each batch of selenium premix.
What does this all mean? For homesteaders, the main message is that selenium is not a simple matter, and no one should rush to supplement rations with it until and unless they have full knowledge of what they,re doing.
This, on fescue, is taken from Countryside 72/4.36 (July/August, 1988):
There is an endophyte-free fescue that apparently eliminates the problems associated with this pasture plant. ( Use fescue with caution, 72/3, p. 7). Studies in several states have shown that calves have significantly higher weaning weights when their mothers have been fed endophyte free fescue. In addition, pregnancy rates for cows on this fescue are much higher than those on traditional endophyte-infested fescues.
In one test, cows on regular fescue had a pregnancy rate of only 50 percent, while those on the newer variety had a pregnancy rate of 100 percent. Weaned calves in the endophyte-free group weighed an average of 78 pounds more than the others.
Some lab tests have indicated that the endophyte-free varieties may be susceptible to aphids, but Kentucky researchers say they haven't seen that in test fields yet. "It's not surprising that the bugs like it," one said. "The cows sure do like it a lot."
In fact a bigger problem may be that the cows like it so much, overgrazing may become a problem. Pastures need to be rotated carefully.
Since this topic first came up, we've been hearing much more about it. Gary Lacefield, Extension agronomist at the University of Kentucky, said his state has 5.5 million acres of fescue pastures and about 95 percent of them have the endophyte fungus.
"We only learned about 10 years ago that the fungus caused the mysterious summer slump in weight gains for grazing livestock. But we have to remember that fescue, even the older, infested kinds, have played a great role in Kentucky." It's not feasible to run out and plow up all those fields to plant the newer varieties, he said.
He suggested grazing the older varieties when they,re young, vegetative and leafy. Cattle can be grazed on it in spring and fall, and be moved to other pastures during the summer.
For hay, fescue should be cut in the boot stage, just before seed heads form.
RELATED ARTICLE:Selenium poisoning
Selenium poisoning (also known as alkali disease and blind staggers) affects all animals, including humans.
It occurs most commonly in certain regions of the west--especially in Colorado, Nebraska, South Dakota and Wyoming, as well as in Alberta, (Canada), Mexico, Ireland, and elsewhere.
Selenium poisoning can be chronic or acute. The chronic form results when feed (forages or grains) contain 5-40 ppm selenium. This can cause loss of hair from the tails of cattle, the tail and mane in horses, and general hair loss in swine. The hooves can slough off, feed consumption decreases, and the animal can starve to death. There are several treatments, most of which require a veterinarian. (One uses trace amounts of arsenic compounds.)
Acute selenium poisoning occurs when animals consume plants with a high selenium content. (Some plants accumulate it.) Vision impairment, or blind staggers, is the common result. There is no known treatment.
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|Title Annotation:||selenium in animal feed; includes related article on selenium poisoning|
|Publication:||Countryside & Small Stock Journal|
|Date:||Mar 1, 1995|
|Previous Article:||The importance of selenium.|
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