Our hay supplier informed us that he treated his hay this year with Propionic Acid and Potassium Zorbate to inhibit mold growth. Is this safe to feed horses? Does anyone have any experience feeding hay thus treated? Thanks.
My horses won’t touch it. Here in Fl., at certain times of year, hay suppliers sneak in treated hay and we don’t know
it’s treated til we get home. the hay may appear like nice hay but my horses antennae go up and protest. they just sniff and walk away, then neigh for good hay.
Guess my horses were not so picky, they vacuumed up treated hay! Ours was treated with proprionic acid, a form of vinegar, smelled a bit like pickles. We found the treated hay to stay wonderfully green, held all the calories of fresh hay, even used over a year later. We did not need to feed as much hay to keep the horses looking good over winter, which is why we had leftovers.
Any treated hay CANNOT be touching untreated hay, since it will pull the moisture out and get moldy. Some years of wet summer, the only hay put up is treated so it can dry fast between storms. I would not hesitate to buy treated hay and feed it to horses. About the only downside is how heavy the spraying makes the bales. Normal 60# bale will be 75-80# to handle. Husband says extra weight is all those calories you don’t lose in normal drying! Ha ha We never have had a bad bale in several thousand bales of the sprayed stuff, last bale was as nice as the first one we used. No spoiled bales at all. Color is rich green inside, though hay might fade slightly on exposed bale end.
Sounds harsh, but any horse not eating sprayed hay here, “must not be that hungry.” I would not offer other hay, he won’t starve or get sick as he adjusts to the flavor over a few days. Some years there was nothing else edible, available for winter hay. They all look real nice in spring. We have fed it to probably 12-15 various horses over the years. None refused to eat it, they left no waste on the ground or in stalls.
Propionic acid has one more carbon than acetic acid, the solute in vinegar solutions. Acetic acid - CH[SUB]3[/SUB]CO[SUB]2[/SUB]H. Propionic acid - CH[SUB]3[/SUB]CH[SUB]2[/SUB]CO[SUB]2[/SUB]H. Propionic acid does smell like acetic acid, but when you add one more carbon the molecule smells more like a combination of fermented hockey clothing and very old cheese.
Mine too.
Best test to see if hay is treated is to chew on a piece – it will have a slightly bitter taste.
We are getting a few “test bales” to see if our horses will eat it. I just didn’t want to make them sick. What about the Potassium Zorbate?? Is it frequently used in connection with the P.A?? Is Pot. Zorbate safe to feed?
Potassium *sorbate is a pretty common preservative. You’ll find it in many oral horse items, such as Red Cell and B-Kalm Paste. Both are safe and approved for livestock use, but it would be impossible to tell you if that particular hay is safe without knowing the concentrations the treatments were used. I would assume (hope) the hay supplier would be knowledgeable enough to make sure he is treating at the approved rates.
Thank you all!! I appreciate the input:)
UPDATE - My Horse LOVES this new hay - as in - he drags me to the hay to eat it! Actually just like me when I walk by a bowl of popcorn. So my concerns about palatability were unfounded. So far - so good. Just thought I would share!
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Great to hear!
FYI, horses actually make their own proprionic acid as a by-product of digestion 
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Glad to hear it. You might want to feed a tad bit less than you fed with his previous hay. As I mentioned, our treated hay kept ALL it’s calories, so they did not need as much to hold their weight.
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Funny! We have one that won’t touch it either. I think it smells awful, but I have a bionic sniffer.
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The last Timothy I got was treated. Ofc Dex won’t touch it. Took a little of it to the pasture horses. Four of them walked away hastily after smelling it, eyeing me over their shoulders as if to say they were too intelligent to be poisoned by me. The old mare however, decided to sacrifice herself for the sake of the herd by eating the entire half bale. Lol. She gets pushed a little at the round bales since the old gelding died so she is very happy to have a bale to herself every day now.
Ha!!! I was really surprised at how enthusiastic they are about eating it! Especially since our grass is still temptingly lush and green. I do notice a slight vinegar scent in the hay but not overwhelming. Very good to know about the calories. Thanks all - as always I appreciate COTH input:)
