I feed my 18yo hunter a mix called 16+ by dodsen an horrel:
Oatfeed, Barley, Alfalfa, Wheatfeed, Full Fat Soya, Distiller's Wheat Grains, Extracted Sunflower, Cane Molasses, Maize, Glucose Syrup, Nutritionally Improved Straw, Vegetable Oil, Peas, Calcium Carbonate, Mint, Dried Carrots, Salt, Unmolassed Sugar Beet, Vitamin/Trace Mineral Premix, Magnesium Oxide, Wheat, Garlic Granules, Dicalcium Phosphate, Glucosamine (0.2%), Prairie Meal, L-Lysine, Marjoram, Dandelion Leaves, Methyl Sulphonyl Methane - MSM (0.05%), Nettle Leaves, Blackcurrant, Kale, Spinach, Beetroot, Rosemary, Rosehip, Pomegranate (0.03%)
He gets that with a speedibeet and a cup of micronised linseed which help throw the weight on him.
There is a 31yo horse at my yard who has 5 "meals" a day all soaked. I think one is a grass nut, one is this 16+, one is a fibrebeet, one is a grass chaff that when soaked makes it like a chopped grass so easy to eat, and the other is his haylage all cut up into bite sizes. Takes them about an hour to prepare his meal before feeding, then he gets to decide which/when to eat as they are all in different buckets. The horse looks amazing for a 31yo exrace horse, and can still be ridden with great liveliness!