I have been feeding him alfalfa cubes this winter to keep his weight up and I went to ride him yesterday and he was very hot and spooky, he is on a very good feed Seminole Wellness dynasport and gets free choice hay but the hay is not the best quality, what could I give him instead of alfalfa cubes that won't make him hot
I strongly recommend that everyone who owns a horse take a course in Equine Nutrition and in Equine Digestion. I preach this to so many people, but unfortunately I realize that it's not something everyone can easily do since they might not have access to these educational opportunities.
Horses do not need "high energy" hay or foods that are high in NSC. They really aren't very good for them and can lead to health issues that could shorten their lifespan. (Secretariat was put down at 19 due to laminitis which was almost certainly the result of his feed being grain and top quality hay). So don't feel bad about the hay not being high quality. I feed low quality hay and pray that my supplier's son will continue supplying it when his 80 year old father stops, because he's the only source in over 100 miles.
The "modern" style of equine has been around for about 10 million years (if we go back to when it was a dog sized animal it's about 50 million, but we're not over concerned with the first 40 million years). In that time nature designed them to live on low quality forage. It's what their digestive system is designed to work with. A lot of long fiber (grass....or hay) and low NSC (grains and grain products are high in NSC). Too much starch creates problems in the hind gut, but I'm not going to get into trying to give a Reader's Digest version of tiny portion of a course in Equine Nutrition or Digestion. I've posted enough stuff on this site to give me writers cramp and poor eyesight from pouring over old class material *laugh* and even then I miss things.
Avoiding "hot" foods is smart. It's best for your horse, because hot foods are high in NSC. Horses do need small levels of NSC (just as humans need small levels of fat) for proper health, but they get enough from low quality hay and from grass (they can get too much from some hay and from grass that is too lush....reason some horses founder in late Spring/early Summer)
The best "cold" feeds I know of are copra (solid remains of the meat of a coconut after 95% of the oil has been extracted) and beet pulp (solid remains of the beet after the sugar has be extracted). Both are highly digestible (beet pulp being fiber, more nutritious than the best hay and handled in the hind gut, copra is so digestible it's taken from the foregut straight to the liver), both are extremely low in NSC and both provide plenty of useable energy (beet pulp is a favorite with many endurance racers).
Word of caution. Beet pulp is high in Ca, but has almost no P. Copra is high in P with low levels of Ca (which is the opposite of what the proper ratio is suppose to be for a horse). I solve this by feeding both copra and beet pulp mixed together so that my Ca to P ration is around 2 to 1, but you can also use supplements to create the balance needed.
I wouldn't worry about the low quality hay. I feed "cow" hay (Bahia grass hay). We've fed that to our working horses since my grandfather's time (and he was born in the 1800's). Timothy, CB, and the host of high quality "horse" hay will almost certainly have more NSC than you want.
A quick explanation for why people feed grain and rich hay. It's a long standing tradition started a very long time ago in Europe. They did not understand equine digestion. They kept the horses confined (so that they couldn't graze to keep the sort of diet nature designed them for). Grain was on hand, easy to store so it made an easy feed. Hay was later looked at the same way as we developed "high energy" hay. Knowledge about NSC and it's effect, how equine digestion worked, and what their nutritional needs actually were didn't come along until much, much later. Although it is interesting that the great horse societies of the world (Scythians, Mongols, etc. etc.) did not feed their horses grain or on high quality grass or hay. They ranged their horses over large areas which allowed them to have a natural diet without some of the problems faced by horses in Europe (and later in places colonized by Europeans).