LOL! Not driving me nuts. TBs are notorious for being relatively hard keepers. They have a higher metabolism and more flight instinct; hence the term 'hotblood.' That said, there are those out there that are very easy keepers and very laid back, too.
You can feed pretty much anything if you do it by weight. There is no "right" feed or "wrong" feed; each has a place in the equine diet, although I'll qualify that by saying there are those I reach for before others. To maintain a 1000# horse at rest or light work with a normal metabolism, you need roughly 20,000-25,000 calories a day. In order to supply those calories, you need to know that:
Alfalfa hay has roughly 1100 calories per pound
Most grass hays have roughly 900 calories per pound
Dry beet pulp is about the same as grass, about 900 calories per pound
Cereal grains such as oats, corn, and barley have roughly 1400 calories per pound
Fats such as vegetable oil have roughly 1600 calories per cup
And if you wish to have a horse on the gain, you need to supply an ADDITIONAL 3500 calories of feed per pound of gain. Since horses are big, most people increase the ration by at least this much.
The cornerstone of the diet is ALWAYS forages. The more of their total calories they get from forages, the better. It yields improved digestive health and mental health. (Chew time is zen time for them.
) Forages inclued hay, hay pellets, and pasture. (And silage, but I don't think that's being used here.)
It's always best to have the hay tested. This only costs a few dollars and most County Extension agents will lend you the tools and help with the labs. Then you have a nutritional baseline for what you're feeding. You can heap TONS of hay on a horse, but if it's not high quality, they can eat and eat and eat and lose lots of weight.
Weigh the hay you feed and make sure you're giving 25# a day. Some grass hays are really fluffy light and are foolers.
Then do the math. 25#hay x 900 calories= 22,500 calories. Your horse needs probably closer to 30,000 calories a day to not lose weight; so what's the best way, given your feeding situation and budget, to get the remaining 7500 calories?
You can feed 7# alfalfa pellets or alfalfa hay, whichever is more economical and works best for your management situation. 1100x 7= 7700 calories.
OR, you can feed 5.5# alfalfa pellets or hay with 1 cup of oil. 5.5x1100=6050+1600=7650 calories.
OR, you can feed cereal grains (which I don't recommend because they acidify the gut and predispose a horse to ulcers, but it's an option.) 1400 calories x 5.5# grain= 7700 calories. Also, sometimes horses on lots of grain get so fizzy that they rapidly fret off anything they gain. Use grain with care; it brings out both the very best and the very worst in horses.
(Gotta say it here; the oats you've been feeding by the cupful have been only a few ounces. This makes virtually no caloric impact at all.)
OR you can use beet pulp, weighed dry and then either fed dry or soaked. 8# beet pulp x 900 calories= 7200 calories.
You can also see how you can mix and match based on your horse's likes and dislikes.
The soybean meal goes into a separate caterogy of supplements. Some vets really like using SBM for feet due to the high lysine content, and it's much cheaper than most hoof supplements. It also contains enzymes which have been shown to inhibit growth, so it's best to not feed soy products to growing stock or pregnant or lactating mares. If you like feeding it for hoof and horn quality, that's great; but less (a quarter cup a day) will yield the same results as more, and it affords little caloric value in the amounts you describe.
Your other supplements sound fine to me.
And all that said, you might find that as winter wears on, that 30,000 calories a day just doesn't cut it for this particular individual, and you might have to increase his ration yet again. Blanketing helps them conserve calories that might be used in staying warm, but are best used in temps below 40 degrees. Also, probiotics are wonderful for horses that are poor doers. It helps to repopulate the gut with the bacteria that's vital for proper digestion and assimilation. Without it, you can feed the very best feeds and it'll skitter on through.
It might be useful to you to figure out what you'd be paying for each of these foodstuffs per calorie. Oil is spendy, as are alfalfa pellets, when compared to alfalfa hay. But if feeding time is short, giving it in a more concentrated form might be best. Most pelleted feeds come in 50# bags, so you can see that if you're feeding 7# a day, you'll go through about 4-5 bags a month. 7x30=210. What does high quality second or third cutting alfalfa hay cost there? If you can get 50# bales for less than $5 a bale, that'll be a substantial savings, not to mention good chew time, and as long as it doesn't displace other things in his ration.
Does this help clarify things for you?
) Forages inclued hay, hay pellets, and pasture. (And silage, but I don't think that's being used here.)
We have gone so far as cutting out all concentrates completely for a week in hopes of getting him into the habit of eating more hay. He just won't. So we have to make up his calories in other ways. He gets a combination of high fat (10% fat) grain with added beet pulp and Cool Calories. This is the result (he's on the left). And he looks like this year round because we up his concentrate in the cold weather. 