Hay gurus of COTH – I’m idly curious about a horse keeping warm through eating. So, if a horse ate say 5 lbs of hay, in general how long would the eating/digesting/fermenting/heat-generating from that hay last? If horse is fed hay at 8pm, will he still be digesting, and therefore presumably generating heat, at 6 am?
(Horse has a lovely in/out stall with a large friend in the next stall who throws alot of heat, and Horse has a full coat that could protect him through nuclear war, and we’re not into the teens or single digits yet in this region of the country; I’m just curious about the hay thing).
I’m thinking not. My horse can scarf 5 lbs of hay in under an hour. It’s a long time until the morning. I try to put enough hay that I know will last until morning.
The general rule of thumb is a horse shouldnt go longer than 4 or 5 hours without forage, and if you can rig up something for slow continuous “trickle feed” that mimics grazing and browsing, that’s ideal.
This is where a good half inch slow feed hay net is so useful. Feed dinner loose and then give him a slow feed net to pick at all night.
It’s not only the eating of hay that keeps a horse warm… it’s the ability to MOVE, to run, to play with others. We got down to -38C last winter overnight. My horses, TB and TBX, live together, in a herd, and have hay in front of them always (round bale- no restrictions), or at pasture on uncut second crop on the hayfield. Good quality hay, alfalfa/grass. Especially if it is cold out, they go for a run. Together. Someone suggests it, and they all go, young and old.
Not enough to break a sweat, but everyone pulls up blowing and snorting. When out on the hayfield when it is cold, when morning is breaking, all are up in the top corner, waiting for the first rays of morning sun. No one wears a blanket, just natural fur works well. If it is cold, make sure that a horse has room to run, to move. The coldest place for a horse is in a confined space. They aren’t stupid, they know how to look after themselves, if given the chance and opportunity.
OP --it’s one I’ve wondered about too —from HS chemistry (51 years ago!) I do know that heat can be produced through fermentation --but enough to keep my horse warm?? seems impossible, and yet they do it! And I have personally had hay “rot” and smoke --wet hay can start a barn fire --again --know it on one level, not sure I understand it though . . .
Related how does eating grass help with keeping warm? We have grass in Florida still but nights have been on 30s and 40s recently. Does eating grass work the same way as hay?
I throw hay to supplement and keep them warm but I’m really interested to know about the grass. Google searches have not yielded answers.
Last winter, that was the coldest overnight temperature of the winter. That was “cold”. “Normal” overnight temperature here in midwinter is around -25 C. Interior of BC, in the rainshadow of the coastal mountains. We were -10 C last night here. No biggie. Happy horses, looking after themselves out grazing the stubble in the hayfield and drinking out of the creek. The coldest place for a horse to be in this area is standing locked in a stall or small paddock.
Due to global warming, winters are much warner here than they used to be. Record here is -56 C, some of the oldtimers still remember this. Much warmer now LOL!
Right, but that’s about the health of the stomach, rather than what’s happening in the hind gut to produce heat as a by-product of digesting fiber.
I’ve looked and looked, and everything I find that has duration in a given spot, always leaves out this part. Stomach? Check. Small intestine? Check. Cecum? Check.
Large intestine (aka the “hind gut”)? crickets
The stomach alone is variable - 15-30 minutes to empty on a normal basis but up to 24 hours if they’ve been fasted long enough.
Food can go through the small intestine to the cecum in as little as 1.5 hours, but can also be 3-4 hours, depending on what the food is (ie hay/grass is slower than pelleted/cubed anything). If you add fat to the diet, this process slows down as well.
The only thing I can find to make an extrapolation is the idea that food can reach the large colon (past the large intestine) in as little as 7 hours. But is that food that was pelleted? Is that hay?
So you COULD make some guess that hay stays in the large intestine around 5 hours - is that the min? Average? I don’t know. That’s taking the min amount of time above for time in the stomach and getting through the small intestine.
So no, if he had 5lb of hay at 8pm, the chances of any significant amount of hay still creating heat in the large intestine is small to none.
But the idea of only having 5lb of hay provided at 8pm, and no other feed until 6am, is not anything you should be doing unless you’re just looking to create ulcers. That’s the real issue, especially with the variables @SharonA1 described.
Thank you, JB. That’s a close enough work-through, I think.
And, steady on, team. My own horse’s hay usually lasts him overnight, and he can always go find alittle something in his pasture 24/7, even this time of year when he might have to hunt alittle. He’s fine. It was an academic question.
Yes. Horses are hind gut fermenters, so whatever they are digesting back there is generating heat.
But I have pondered the same question as the OP: Does it make any sense to through my (unclipped and fat) an extra flake when I leave at night if the coldest temps will be 10 hours later?
In part it’s the fermentation but also it’s calories that can help them in winter especially if they don’t have a lot of stored energy on their bodies and they tend to run colder. Calories are a unit of energy after all. And heat is energy.
It was an academic question.