7 months colt confirmation

No, you want a growth horse feed. 1 lb per 100 lbs body weight, maximum of 6 lbs of feed per day (3 lbs per meal). Also at least 10 lbs of hay per day. Make sure he actually gets all that food and not the adult horses. That means he needs a separate area to eat in. My colt did better after weaning because his dam was inhaling the hay and he wasn't getting enough, meanwhile the mare was as fat as can be. As soon as he was weaned, he gained really well.

Pastures go dormant at this time of year, so you need more hay. What type of hay do you buy?

I was looking at a horse for sale. They had yearlings turned out on a sparse pasture. They were the size of my 6 month old colt, due to lack of nutrients.

Given how immature this colt looks, I'm betting his legs will straighten out as he grows. But he needs better nutrition.

Alfalfa has a 5:1 ratio of Calcium and phosphorus. Beet pulp is 10:1 calcium and phosphorus. Both are too high in calcium without supplementing phosphorus. Oats has a 1:3 ratio being higher in phosphorus.

If you switch the hay to alfalfa, you can safely feed oats to balance the calcium phosphorus ratio. I would not use beet pulp as it's too high in calcium and will imbalance your diet. Grass hay has an ideal ratio of Calcium and phosphorus but is lower in protein and energy.

You can feed 8 lbs of alfalfa, 2 lbs or more of grass hay and 6 lbs of oats- this should give you a 2.5 to 1 ratio of Calcium and phosphorus.

Define decent hay?

If you can't get alfalfa and are just trying to balance Calcium and phosphorus in an oat/beet pulp diet, you can feed: 0.85 kg of beet pulp per 1 kg of oats

Fodder beet is not high in either calcium or phosphorus but can be a good source of energy.

The problem with the above mentioned diet is protein deficiency. This diet is also deficient in minerals.