We bought a HUGE load of hay this winter from a reputable grainstore, 70 lb gorgeous bales of second cut that the horses love, we filled our barn with it and I'm guess there are about 800 bales in there, maybe more.
Originally we had 5 horses here, some in for training, a few of our own, and plans for more boarders. Then, I discovered I was pregnant so we are not going to accept more boarders and the training horses will be going home, which will leave 2 horses here,, who are on grass in the summer. I'm worried about the hay - it's so nice and it's stored in a airy barn that we can close up when it's misty/rainy, but has plenty of airflow and is not a wet environment at all. They hay had been dried and stored previously to being brought to our farm as we purchased it mid-winter (so it's not fresh or still drying).
Can it store for a longer period and not go bad? I'm estimating it will more than get me through spring, summer, and next winter for just two horses, and I hate to try to sell it because it's so nice and the horses love it, and it's all neatly stacked in my barn loft which is not easy to get to! I can also hay test if I plan on feeding it all to my horses and see what minerals/vitamins need supplementing...
The barn I rent is owned by a hay farmer. Last season we had second cutting well through Spring and it was perfectly fine. I think a lot depends on the actual content of the hay when it was bailed. As you mentioned, staying dry is the key thereafter. Would have used it even longer but it sold too quick.
"Truth is incontrovertible, malice may attack it and ignorance may deride it, but, in the end, there it is." Sir Winston Churchhill
It will last indefinitely if kept dry. It will eventually get dusty, but in my experience, if you use it all up within two years you'll be ok. You do lose quality, for example, most of the vitamin A is gone in the first six months. Hay is done once a year in the US (in two or three cuttings) so even if it's new to you, if you are buying it in march or April, it's from last summer. If we have any left over from the year before, I use it for bedding the broodmare stalls. It's much cheaper than straw in this area.
If I were in your situation, I would use it. If you notice it getting real dusty, then you might rethink, but you should be fine.
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I once picked up a load of free hay that was 2+ years old - had been stored in a dry barn and had only dust that had settled on it. The horses LOVED it and we knew it was good as forage and not necessarily as a high quality source of nutrition.
If the hay is good to start with, I would have no problems with feeding it as it ages. Your barn storage sounds great, so it is being kept well, shouldn't lose much in feed values. If the barn is kept closed, dust levels should be down as much as possible.
I have purchased "old hay" when it was a good savings, horses ate it fine, looked fine. Worth getting for the savings in price. They didn't need "extra" or larger portions than normal either, stayed at the correct weight while we used up this hay.
I have about 20-30 bales of 1st cutting hay from 2010.
New hay delivered June 2011 was stacked on top of these leftover bales.
As I come to them, I am feeding and really do not notice any loss of quality. Horses don't seem to know the diff either.
Sometimes the only way I know it's an "old" bale is because hayguy used blue twine in 2010 and orange in 2011
Like OPs have said: as long as your storage keeps it off the ground, ventilated & dry, your hay s/b fine for another year.
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Sam(Jaybee Altair) 1994-2015
And another thing you can consider is selling off some of that hay toward the end of winter here... with only 2 horses in residence, and both of them on grass pasture in the summer, you are going to have that 800 bales for a while... I'd say keep 200 and sell the rest for a nice premium price!
I'm currently feeding some 2009 hay that is pretty good, not great, but it was the only really low NSC hay I could find for my IR guy, so it works for him. As others said, as long as it was good in the first place (put up well) and kept dry, it can last a long time. But like someone else mentioned, you might want to sell some here at the end of winter as you might be able to even make a little money on it. Around here, hay stocks are low and prices are high, so that would be on my mind in deciding.
I'm still feeding 2010 hay. I finished the last bale of the regular stuff last night but expect that I'll be feeding the leftovers of the super premium soft bladed 2010 hay to the old geezer at night at least through July (he eats 10# per night and there's ~1400# left). Aside from a bit of dust on the outside of the bales I haven't noticed any decrease in quality and they both hoover it all up.
I never intended to feed 2010 hay all winter, but I found a great deal on some organic orchard grass last May and bought it in anticipation of high hay prices for 2011 hay. Glad I did.
We're moving on to the 2011 hay now and I expect to be feeding it well into next fall as I (again) overbought.