Start early because you'll have to constantly adjust what you feed as the season progresses! I start everybody on 2 cups of vitality 14 and 1 cup of soaked beet pulp twice daily plus a chunk of hay. I use alfalfa basically because good quality grass hay isn't readily available in my area. Some people use soaked alfalfa cubes or alfalfa pellets. Then you monitor them constantly for body condition. By the end of the season I have horses still getting the 2 cups of grain, and some getting 4 cups 2x daily plus a 2 cup feeding midday. The beet pulp stays the same. On hay I give more in the winter months they use it up staying warm, by spring, some of them are down to a small handful, some can still handle a pretty good chunk. Then for the supplements, some people add a TON of supplements, but one that I think is important is the daily wormer, you could add an iron supplement, coat conditioners etc. It is just up to the individual horse, some of them do very well without alot of stuff added in. Realize that when you really get those grain amounts up there you have to be able to get them out and work them or risk health problems. It is a fine line we tread to get that lovely topline, tucked up tummy and oozing with health and vitality!