I have been reasearching equine nutrition for years. And lately, Mini's specifically. This is my opinion.
It's been proven that diets high in NSC (non structural carbs) cause all kinds of issues in horses. Ulcers, laminitis, founder, IR, obesity, hindgut acidosis, etc. While a horse in heavy work will need a higher level of carbs to aid in muscle function, there is still a limit.
It's common knowledge that Mini's are prone to weight and metobolic issues. Therefore, common sense tell me that they should DEF be kept on a low NSC diet. Especially if they have previously foundered or had a bout of laminitis.
I choose to feed a grain free, low NSC diet to ALL my horses. No sweet feed. I have barrel horses as well as Minis.
When I changed my big horses over to this diet, I saw a huge improvement in hoof health as well as hair health. I am also learning to trim. It's been a process over the past couple years, but through proper diet and trimming, my barrel horse who once couldn't go one step barefoot, can now be ridden/worked barefoot. The changes in her hoof form/health have been quite amazing. Thickening of hoof wall & sole, heels widening, frog widening, opening up and getting more full, etc.
My Mini mare was previously foundered and was in the middle of a laminitic flare up when I got her. She was well taken care of, but a lot of people AND farriers are pretty clueless when it comes to hoof balance and laminitis/founder. I have also been working on her... both diet and proper trimming. She has also had HUGE changes in her hoof form/health. She hasn't taken another lame step since I've had her.
Oats, corn, barley, molasses.... all things I stay away from b/c essentially, they are high NSC. A feed that is based on one of those ingrediants is going to be high NSC. Now, I'm not saying NEVER use them. For example: My barrel horse is on 2lbs of steamed crimped oats daily. I add the oats to her diet when she is in work/training and/or in the winter time. I add them to her normal feed for calories alone. She requires a few more calories than my normal feed can offer in winter and when she's in work. But, I would never go over 2lbs of oats daily b/c then the NSC level jumps up too high for my liking.
When choosing a feed, I look at the ingrediants and I look at the formula. I don't want to see corn, oats, barley, etc listed on that ingrediant list. I want to see things like soybean, beet pulp, alfalfa, etc. I also want a fixed formula feed. Fixed formula feeds are the same from bag to bag. The ingrediants never change. They are fixed. There are not a lot of feed companies out there with fixed formulas. Most of them are low cost formulas. Low cost formulas can vary from bag to bag b/c the comapny will substitute ingrediants with whatever is cheapest at the time.
The feed brands that *I* would/have use/used are Triple Crown, ADM & Buckeye. They all have fixed forumlas recipes and offer grain free, low NSC feeds.
Currently, all my horses are on Triple Crown Lite. It is a grain free, low NSC, lower calorie feed. It is meant to be fed at 2-4lbs per 500lbs of body weight for the average horse. Or, 1lb per 500 lbs of body weight for Minis & ponies.
Something to keep in mind.... calories and nutrition are two different things. You can have enough of one and not enough of the other and vice versa.
My horses feeding plans at this moment are:
7yr old Quarter Horse mare, barrel horse: 4lbs TC Lite, 2lbs oats, free choice mixed grass hay (per day)
7yr old Paint mare: 2lbs TC Lite, free choice mixed grass hay (daily)
17yr old Mini Mare: .75lb TC Lite, 1/2 sc Remission, free choice mixed grass hay (daily)
1yr old Mini colt: .35lb TC Lite, free choice mixed grass hay (daily).
All hay is in a slow feed net.