There are hundreds of different feeds available for your horse, and to know what to feed can be so confusing, especially with all the yard “experts” around.
I believe there are scientists that have studied for years, and are real experts, that have made balanced ready-made nuts or mixes for your horse, so you do not have to worry. I also believe that you should be very careful when adding anything to these mixes, as it then upsets the balance. There are many ratios you must be careful not to upset, for example phosphorus and calcium must be carefully balanced. So, unless you are willing to look into all of these, I would leave it to the experts who make the feeds, and not alter it. The only decision you really have to make is what mix and how much.
These decisions are also easy as the description of the mix just has to match your horse- calm and condition for a slimmer horse that can get excitable, cool mix for horses that become excitable easily, veteran for the aged horse etc.
The amounts to feed are on the packets as well, so feeding could not be simpler.
I will briefly cover some different types of feed just for general knowledge.
I have covered hay and haylage in a previous level and do believe that if your horse has turn out, and a good supply of meadow hay or haylage, that is all your horse needs. The exception is if you are competing at a high standard, your horse is doing a lot of work or has a medical condition.
In my riding centre, most of the horses and ponies do about 3 hours of work a day. That includes beach rides, jumping lessons and gentle treks. The majority have fairly poor grazing but adlib hay or haylage when in and over winter. The only extra feed is a cup of pony nuts when they first come in, just as a treat. The biggest issue we seem to have is that they are a little overweight. They rarely suffer from colic or laminitis and the ones that have, have been as a result of other issues (tempting fate again!!). The horses at the centre are generally well with lovely shiny coats and good feet. They are all wormed and their teeth are checked yearly so this all helps. I have had many horses and ponies come in with a huge list of feeds they must have and, within 3 months, are on a cup of nuts and looking so much better.
That said, if your horse is not looking good, you must find something that will rectify this- worming, teeth and a general health check are a must. Then start with checking the quality of your hay or haylage, making sure it has a good variety of grasses. After this, then look at adding more hard feed, but only to the recommended amount.