Don’t feed moldy hay to horses!

Mar. 23, 2013 @ 08:14 PM


That sounds like good advice, and in fact is the title of a University of Minnesota Extension publication written by a host of Extension specialists from several states. It’s also good advice for feeding cattle, sheep and goats. Usually it’s pretty easy to tell if hay is moldy, but if it is not obvious, then a forage test may be needed to confirm the hay is free of mold and the accompanying spores and dust.

It doesn’t take much moisture for mold to grow in hay. Moisture levels above levels above 14-15 percent with no preservative added can result in moldy hay. The mold process causes heat, which in turn reduces TDN and binds up protein molecules, making them non-digestible. However, that isn’t the main problem with moldy hay. Molds produce toxins — a whole host of them, including Aflatoxin (AFL), Deoxynivalenol (DON or vomitoxin), T-2 Toxin (T2), Zearalenone (F2) and Fumonisin (FB1). They are all bad news, but some can be tolerated in very small amounts. However, FB1 should not be present in hay. Tolerance levels for the other four are:

• AFL - 50 parts per billion (ppb)

• T2 - 50 ppb

• DON - 400 ppb

• F2 - 100 ppb

As you can see, these are pretty low levels of concentration. AFL is considered carcinogenic; DON causes reduced feed intake and is implicated in colic cases; T2 causes digestive tract irritation and has been implicated in colic; F2 reduces fertility and reproductive performance; and FB1 is implicated in impaired immune function, liver and kidney damage, and a condition known as moldy corn poisoning, hence the recommendation for zero FB1. More details and definitions on these toxins can be found in the publication, “Horse Feeding Management; Feed Sampling and Analysis.”

The biggest problem is that moldy hay is very dusty and full of mold spores. Animals can develop respiratory problems similar to asthma when fed this stuff.

Tips on reducing the affects of moldy, dusty hay include:

• Do not feed dusty and moldy hay and grains.

• Use dust-free bedding

• Don’t use old moldy hay as bedding.

• Place feed at a lower level so particles are not inhaled

• Keep horses out of the stable when sweeping and cleaning

• Feed hay outside

• Soak dusty hay from 5 to 30 minutes before feeding

• Store hay away from animals and keep it dry

• Make sure stalls and stables are well ventilated

Insist on seeing a forage analysis before buying hay. Hay is expensive and we need to make sure that we are buying a good product. If one isn’t available, it is a good idea to send a sample for analysis on each load of hay purchased.

The test for mycotoxins is free of charge if the nutritive value is not tested. However, for $10, the information on protein, digestibility and micronutrients in the hay is well worth the money. Adding the “freebies” like mycotoxin testing and nitrate testing makes a good value a great value.

For more information on testing forages for molds and mycotoxins, contact the Vance County Cooperative Extension office at (252) 438-8188.