Feeding Mustang weanling-yearling colt

Two weeks ago I had to say goodbye to my old gelding, my best friend of nearly 20 years. This left us with a lonely mare in addition to our own heartache.

We adopted a reservation Mustang colt frm a feedlot just over a week ago. He is roughly 12.1hh, have not measured for weight yet, and is in the 6 to 10 month age by his teeth. He’s doing great! Already easily halterable and leading, loading, picking up front feet and grooming. He will be gelded asap.

He is eating orchard and alfalfa free choice and quite a lot of it, (Haven’t weighed but he gets two decent sized alfalfa flakes and two orchard daily, cleans most up, this is as much as my 1800+lb mare eats a day!) and just started taking pelleted feed ( I’m feeding the remainder of my TACO and complete Senior to finish what we had from my old man). I’m trying to decide the best feed to support him as he grows. He is in a good weight but is more belly than topline. My two considerations are between a simple/ standard ration balancer (Purina or Nuterna) or as I’m a fan of Ultium products trying their Ultium Growth. Thoughts? The two in his herd that I belive are his parents are large Mustangs at roughly 15hh and thick broad horses. I want to get the best growth I can without riskinh DOD.

I would be feeding a mare and foal grain until he is a little older, then switch over to ‘senior’ feed. If he starts getting porky switch to a ration balancer.

You are lucky in that he’s still young enough that giving him really good nutrition will improve his growth; bones, muscles, height, etc. Assume that before you got him he was getting a poor diet.

I would also be supplementing with a vitamin and mineral supplement on top of the grain. They sell lots of ones targeted for foals. Make sure it’s got calcium in it.

1 Like

Since he is going to be prone to metabolic issues, I would treat him more like he’s EMS, even while growing.

I would use a ration balancer, keep calories on the lower side and keep him lean.

He’s eating some decent amount of alfalfa already, and while it may be that the alf is helping the ca/phos ratio of the OG, I wouldn’t be adding MORE calcium, not unless a diet analysis said it needed to be done.

I also wouldn’t start with a mare&foal or growth feed since he’s “in a good weight”. He doesn’t need all those calories. Keep him leeeean - easily seeing the last couple ribs is totally fine, and even good.

A good diet with your hay, and a balancer, will be more protein than he’s been getting, and that, plus the (likely) increase in quality of the forage will help the belly situation. And, some foals just get a belly, especially if he’s closer to 6 months than 10, as his digestive system is still maturing to be able to digest forage more appropriately.

If you are feeding the recommended amounts of any feed, I would not be adding a general v/m supplement. It’s easy to OD on things like selenium.

I would say absolutely no to Ultium. That’s a lot of calories as-fed, and I’m not a fan of the higher NSC in general (it’s not HIGH, but I prefer to not have it approaching 20% for foals), and given his predisposition for metabolic issues, it’s not where I’d go.


Is there a reason Mustangs are predisposed to metabolic issues outside of genetics? They’re so varied in their genetics even within their HMAs (mine is from Warm Springs but is a rez horse not a BLM) it’s surprising that they would be predisposed as a whole. I wish we had a genetic test for this predisposition, hopefully someday.

Just that in general, given that the ones who survive and reproduce are able to get by with “less than”, they are hardier, more efficient in their metabolic processes, and that’s what gives them the predisposition.


I got my current youngster almost 2 years ago form the human society rescue ranch near me. He was a yearling. They were feeding him Ultium Growth and he looked fabulous. They were feeding 4 pounds a day.

I couldn’t afford it so I changed him slowly over to Purina Impact Mare & Foal (as per my vet’s recommendation) and for the next year he just kept on looking good and growing great. I kept up the 4 pounds a day.

When he hit 2 I switched to Strategy Healthy Edge and now ( at almost 3) he is on a RB as he just doesn’t need the calories.

All that to say I had good luck with all 3 of those Purina options on my young growing guy.


They aren’t. Mustang types are so varied that you really can’t generalize the whole breed. A Mustang pulled from one herd will look nothing like one from another. It’s a bit like saying all AQHA’s are predisposed to metabolic issues. I have one who could eat me out of house and home, and other who gets laminitis from just thinking about grass :slightly_smiling_face:

1 Like

Remember that these two got this way without anyone feeding them anything special. If your fella is indeed their offspring, he’s already got the genetics to be a hearty, easy-keeping type of guy who will thrive without needing a lot of extra stuff thrown at him.

I’d stick with free choice high-quality hay and a good ration balancer for now. He’s going to go through awkward “ugly duckling” stages at this point of his life, and I bet his parents did too. That’s okay, and better than overfeeding him and causing potential issues.


They aren’t.

I think that they tend to be “easy keepers” being usually smaller and stockier and having to survive on almost nothing, but the herds can vary wildly on their background genetics. There is a tendency today to label any horse that doesn’t need a ton of feed as metabolic. I wouldn’t leap to that without some vet work first. Most easy keepers might simply need limited time on grass, hay in a net, and a ration balancer.

Both my mustangs get a ration balancer and free choice grass hay in a hay net. My mare is more of a hog but my 2yo seems to be pickier and fine on the grass in his field. He’s got spurts where he looks thin or fat.

They aren’t a breed, they are a type. And as a type, over many generations, they have survived on “less than” compared to domesticated lines.

In general, yes they are more predisposed to developing metabolic issues than many other breeds. That’s not my opinion that’s the result of people studying breeds or “breeds” who have developed insulin resistance (EMS)

“Predisposed” doesn’t mean all.

Pony breeds, domesticated Spanish mustangs, Peruvian Pasos, Paso Finos, Andalusians, European Warmbloods, American Saddlebreds, Arabians, and Morgan horses are more commonly affected than Thoroughbreds, Standardbreds, and Quarter Horses.
Fat, foundered horses: What is equine metabolic syndrome? (Proceedings) (dvm360.com)

Note that TBs are in the list of not being predisposes, yet there are TBs who become IR

But that is exactly what makes them more predisposed.

And that isn’t correct, but that IS what makes a horse more susceptible to becoming metabolic, that’s the point

You can’t predict. Blood work on an easy keeper who is simply and easy keeper is going to be normal

Yes, that is the point! Keep their weight down. Don’t feed high NSC feeds even if they do need some extra calories.

“predisposed” doesn’t mean HAS, or WILL HAVE. It means all else equal, if you let that horse become and stay overweight, their genetics mean they are more likely to develop EMS than, say the overweight TB

Clearly, there is also a genetic predisposition towards development of obesity that has been referred to as having “thrifty genes”…

(from the same article)

Epigenetics can turn on that “thrifty gene” which then becomes inheritable. It happens in people too.

The more those predisposed breeds (or any horse really, but especially those) are allowed to get and stay fat, the greater their chances of developing EMS.

Start early treating these horses as if they could become IR tomorrow. An overweight mustang is simply a bigger risk than an overweight TB. Right off the bat, even if they are good on, and need the grass from Spring-Fall to keep weight on as a younger horse, keep supplemental calories on the lower NSC side. Work to keep them leaner while young.


I just don’t see the need to tell someone their yearling is going to have metabolic issues when we don’t know that and to urge keeping them thin.

1 Like

Goodness, where did I say the were GOING to have metabolic issues? Once again, “predisposed” does NOT mean “will”

Where did I say “keep them thin”?

Lean is not thin. I said seeing the last couple ribs is fine, and in a foal, even desirable. It is GOOD to keep them lean, for a whole lot of reasons, including joint health while the physeal plates are still open. EVERY young horse should be kept lean.

The entire point was to just feed them as if they could become metabolic.


Thank you for all the information. I am going to start with a Ration Balancer and see if I like how he’s going. His herd was all in good weight and wide (except nursing mares including his possible dam who looked the worst I’m thinkinh because he was nursing trough some of winter) though they have been being fed high quality feed in the feedlot so who knows. They do not look the shirt backed short stature archy type of spanish mustang, more like short warmbloods or stock/thoroughbred. I appreciate all the input and knowledge

Know that his weight may easily fluctuate between a little chunky to a little thin, as he goes through growth spurts, just like human children. I like to keep a small amount of alfalfa pellets in the mix (or whatever hay pellets you prefer), and then if they look a little too thin during a spurt, I can jump that up to a couple pounds to help with calories, and then back down to the handful when they settle

What you don’t want to end up doing is sacrificing nutrition to keep calories low (ie feed only 2lb of a growth feed when he should get 6), or feed too much nutrition to increase calories (ie don’t feed 6lb of a ration balancer)

The balancer + forage pellets just makes it easy to keep the nutrition, and alter calories


I really think he would do better with the Ultium. It has more of what he needs as he is still young and growing. My vet said no to the RB when I asked him about feeding it to my yearling and I agree.

My gelding is a QH so you know he will be more like a mustang in food requirements but he really needed a more calorie dense feed and from the description so does yours right now. He was never fat but it helped to keep his weight fairly steady during the growth spurts.

Of course you can do as you see fit but if he is thin on a high quality feed now that tells you something. You can always change things as he ages.

Many ration balancers have specific feeding instructions for the growing horse, including a weanling.

Growth feeds have WAY more calories than ration balancers, as-fed, and most foals don’t need all that.

Ultium Growth would need to be fed at 6lb for a 500lb foal. That’s 422gm protein, 38gm calcium, 19gm phosphorous, 245mg cu, and 736mg zn

Enrich Plus (sticking with Purina) would be 2.5lb (up to 3 or so) and is 363gm protein, 36gm Ca, 18gm Phos, 210mg cu and 568mg Zn.

cu and zn requirements are already well-exceeded in a serving of each. Protein is half-ish to more than half in each. Ca and Phos are met to almost met.

And that’s just the feed, that doesn’t even account for what’s in the forage.

More isn’t always better.

Ration balancers are TOTALLY fine for growing horses.

Either one is fine. Really. I personally would rather had to end up putting weight on a foal (within reason, no need to make them skinny), than try to get it off.


Really you shouldn’t let any horse get overweight. Especially when they are young.

However, because of the way that BLM mustangs are kept, they tend to have nutritional holes. As someone who has a Mustang the one thing I wish I could have done for him is make sure he had all the nutrients he needed when he was a baby. Sadly I couldn’t do that because he was in a holding pen, and because of that he didn’t grow up to his full potential. He has some issues that are likely directly related to the poor nutrition of his ‘childhood’. So if I had a Mustang foal, I would be trying to fill those gaps ASAP for that baby. It’s not a normal foal, you have to treat it a bit like it’s come from a neglect situation nutritionally wise. In a normal foal? Yeah, maybe a ration balancer would be enough. But a normal foal would have had a mama on good grain, vitamins, good hay, etc.

1 Like

He isn’t BLM but was a feedlot rescue (Rez horses are not regulated by BLM) so nutrition is hard to say but he looks pretty really, just potty. Being in the PNW we have quite nice hay readily available and what the feedlot was offering looked quite good. I think the protein of a ration balancer will help fill out his ribs a bit and hopefully tuck up that tummy a bit. But overall he’s is a good weight I just want it in better places lol
He already seems a little larger just on alfalfa and orchard.

I’m trying to figure out how to post a picture fir y’all to see his filthy fuzzy self


Horses are designed to eat low quality graze with huge amounts of roughage and to move large distances during a days consumption. They are also designed to become lean during the winter and then put on condition during the summer. Then we humans come along and decide that we want horses well covered all year and we worry if ribs appear as the winter ends. We worry about our horses getting cold and cover them in rugs which means they don’t expend energy keeping themselves warm so they stay fat. Even as we continue to feed them so fat builds on fat. And we prevent them walking around by keeping them tucked up snug in a stable. In addition, we ration food to set times and quantities which is a bit unfortunate for a natural trickle feeder. So it really isn’t too surprising that domestic horses, or mustangs off their range, develop metabolic disorders. It is ‘genetic’ in the sense that it how they evolved to live but it is actually management that prevents most metabolic problems. The native mountain and moorland breeds in the British Isles are a case in point: to keep them healthy, less is more.


If you haven’t already, do a fecal egg count on him and then deworm. He’s probably very wormy, having been feral and then at a feed lot, and may need multiple doses (obviously, let your vet determine this). I would go with a ration balancer of the choices you listed. You want him to put on weight, but he doesn’t need to blimp out fast. Slow gains are good.