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Poisoning problems rise during drought conditions
Posted July 11th, 2007 in Agriculture & Food: Animal Agriculture
During a drought, preferred forage becomes limited in pastures and hay fields. Animals become hungry and start to eat those plants, which are available. Not all of these plants are good and nutritious. Some plants are toxic and, if eaten, can cause death.

Crops grown and harvested under drought conditions can cause problems. But, using good judgment should keep these problems to a minimum. Introduce suspect forage and feeds gradually over several weeks. Animals can then adapt to higher levels. Do not feed suspect materials to hungry animals. Test, when in doubt, for nitrate and mycotoxins. Severely restrict or stop intake of suspect materials if problems are encountered.

In dry years, poisoning most often occurs in overgrazed pastures. Check your pastures for toxic plants. Pastures are subject to many potentially harmful toxic plants. Exposure can come through weedy pastures, hay, along ditches, in wooded areas, in corrals and holding lots. Signs of poisoning may include chronic wasting disease, abortions, congenital defects, and death.

Ferns, night shade, crotalaria, oleander, sicklepod, horsenettle and many other plants, which stay green in a drought have toxic components. Fungi known as ergot are common in the seed heads of warm season grasses such as Dallisgrass and Bahiagrass. Prevention of poisonings requires you to know that you have a problem, and to move cattle away from the hazard when grass is short. Supplementing cattle with feed and hay may suffice without having to move them. But watch the grazing patterns of the cattle for signs of substantial amounts of toxic plant material consumption.

In recent droughts, damage to corn and grain sorghum crops used feed livestock have brought up many questions concerning nitrate poisoning. Here are some major considerations: Don't feed drought-stricken forages for one to two weeks after a recovery rain. Don't cut drought-stricken forages with known high levels of nitrates for hay, since nitrate levels do not leach out of the forage when cut for hay. The best method is to harvest forage as wet silage and let it go through a 21-day heat and fermentation process before feeding. As much as 50-60% reduction of nitrates is reduced by this process. Test all suspect silage and hay for nitrates prior to feeding. Dilute suspected high level nitrate feeds with known low nitrate level feeds. Don't allow hungry animals free access to suspect forages. When cutting suspect forages, mow at a higher level than normal to avoid the higher nitrate-containing portions in the lower stalk.

Some feeds and forages may contain highly toxic substances produced by molds. Material with relatively small amounts of mold may contain these poisons. They are more likely to be present in corn and small grains than in forages, hay and silage. Mycotoxins can be produced on some feeds before they are harvested and others develop during storage. These molds can have a detrimental effect when fed to most livestock including swine, poultry and cattle.

If you need more information, contact the Lee County Center of North Carolina Cooperative Extension at (919) 775-5624.

Tyrone L. Fisher is Area Specialized Agent Livestock for North Carolina Cooperative Extension in Lee, Harnett and Cumberland Counties.
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Date Posted: 2007-07-11  

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