STRATHMORE, Alta. – Mouldy hay should never be fed to animals when other options are available, says a veterinarian toxicologist.
“Mould is ubiquitous. You find it everywhere,” said Joe Kendall of Alberta Agriculture during a recent feed and forage seminar in Strathmore.
“The question is, when does it become a problem?”
Mould is a living organism that needs energy, vitamins, proteins and minerals. When it grows on hay, it uses the fat, proteins and carbohydrates of the hay for its growth and consequently can reduce the energy content by five to 10 percent.
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Mouldy hay is less digestible and less palatable. It results in lower dry matter and nutrient intake, which affects growth and milk production.
Moulds produce spores that can be inhaled and cause respiratory problems such as pneumonia and increased incidence of abortions.
For example, it could lead to a mycotic infection, in which mould grows in or on the animal.
Poison travels through the blood stream and may eventually attach to the placenta. When that happens, the fetus does not get any nutrition and dies.
Mycotic abortions are not common and may only be six to 10 percent of diagnosed abortions.
“It does not cause an abortion storm and it is not communicable from one animal to another,” Kendall said.
Problems can increase if animals are fed in confinement and there is no place for the spores to disperse.
Mycotic abortions usually occur at six to eight months gestation and does not affect a cow’s future fertility.
Respiratory reactions result when animals inhale spores, which may lead to chronic interstitial pneumonia. The animal struggles to get enough oxygen and a weakened cow may also abort.
Some moulds may produce mycotoxins. Each requires specific growing conditions with warmth and high humidity. Mycotoxins are not part of the mould, but they produce a toxin that is specific to that mould. There are hundreds of strains and each is unique.
Ruminants are more resistant to mycotoxins, but they could cause decreased feed intake, immunosuppression, liver disease, infertility or abortion.
These tend to be a greater problem in grain than hay because they are usually concentrated in the seeds. Mycotoxins are relatively uncommon in Alberta.
“Our temperatures are too low and our humidity is too low,” Kendall said. “It can happen, but it is very rare. Ruminants are much less susceptible. Swine particularly are very sensitive to most mycotoxins.”
New strains are constantly being identified, and little is known of the combined effects in animals. These effects are hard to diagnose.
The most important strains in Alberta are vomitoxin, zearalenone and ergot. Hogs vomit if they eat grain containing vomitoxin.
Zearalenone and vomitoxin are both produced by fusarium in grain and are often found together. Animals will refuse to eat the infected grain. The mycotoxins are also immunosuppressive.
“It will be subject to a lot more opportunistic infections, so you will see more scours in calves or more pneumonia,” he said.
Zearalenone reduces fertility and may cause abortions or swollen mammary glands.
It is debatable whether ergot is a mycotoxin. It grows in seed heads and replaces the grain.
Test for mycotoxins
The two forms of mycotoxins are gangrenous type and nervous syndrome.
Gangrenous is more common in cattle and causes a condition where blood vessels cannot dilate and animals cannot dissipate heat.
In winter, animals try to maintain heat and can end up with frostbite leading to lameness, loss of tails and ears if their circulation is poor.
Producers who suspect these diseases should test their hay for nutrie nt quality, mycotoxins, mould spore counts and fungal identification.
“Find out exactly how bad it is. The problem is getting the representative sample,” Kendall said.
Grabbing a handful of black hay is not enough. Ten percent of the forage should be checked for a good assessment.
Take samples from 40 bales if there are 400 altogether, although Kendall agreed this is not always practical.
“Ten samples is absolute minimum. We would prefer to see 20,” he said.
Use a probe to take samples that represent the entire field or lot of hay. The probe should go in perpendicular to the way the hay is formed. Place the samples in a Ziploc bag and seal. Mix up the bag so that it is representative, regardless of what happens in the lab.
Ask for a nutritional analysis of the hay and what supplements might be needed to get the ration back into proper balance. Consider getting a mould analysis and spore count of the sample.
Do not feed the hay in a confined space. Always feed it outside.
Seek help from a nutritionist who can suggest a proper balance of good quality ingredients. Introduce the poor quality slowly in small amounts because it is unpalatable.
Avoid feeding to pregnant animals or young lactating animals
Watch livestock closely for poor performance, respiratory problems or lower feed consumption. The reactions can be subtle.
For more information, visit www.gov.mb.ca/agriculture/livestock/beef/baa05s27.html and www1. agric.gov.ab.ca/$ department/deptdocs. nsf/all/agdex6938? open document.
