Hi Micah! Welcome to THA!
My thoughts:
1) The term “weight loss” is an interesting one because it does not describe anything specific. For example, If I cut off my arm and threw it away I would have “weight loss.” I prefer to be more specific such as muscle loss or fat loss.
To interpret what you are saying here, despite 6 months of SBM he is not adding fat but is maintaining muscle. As Kathy says in her comment, from an athletic view there is adequate muscle. In addition, for an athlete, adding more fat not only adds unnecessary weight that applies more concussive force to the limbs but excess fat is also inflammatory to the whole body. See the “Fat and Physics” rounds). I agree with Kathy that from this angle, he looks great.
2) Sugar beet pulp is a byproduct of our sugar industry and should be thrown away. Manufacturers say it is a low glycemic index source of fiber but it still is the outer hull of a plant with possible inflammatory lectins (see the nutrition course). Forage (pasture) is a better source of fiber for horses followed by hay.
3) What is “3 feedings” mean in your comment about total amount of hay consumed? A working large horse should be getting at least 20 pounds of forage per day (½ of a 40 pound bale of hay) in addition to a minimum of 1 pound soybean meal (SBM) for the amino acid content. Remember that hay has starch (sugar) which stimulates insulin production and production of body fat. If he wants more hay then adding it would also add body fat.
4) Florida grass in the sub tropics (below Orlando) is different than grass in the rest of the US where starch is stored in the roots. This allows the plant to survive hot and dry conditions. Allow your horse to accommodate to the FL pasture which may take a year.
5) The hottest month here is September and some horses need to acclimate to the heat. Maybe he just needs a year to get used to FL. Most humans need 2 years to get used to summer here.
6) Adding SBM to add top line takes at least 6 months and usually 1 to 2 years for full effect. It also takes this long to get bad hooves looking good again.
7) As Kathy mentioned, adding Coolstance will add fat but I usually recommend this to older horses who have been chronically inflamed. If you decide to add this then be vigilant with your eyes as you do NOT want him to become over-fat.
8) Often how the horse “feels” is the best indicator that you are on track with the nutrition. If there is abundant energy and a willingness to do his job while staying focused and being a willing partner then is adding fat only for looks? More important than looks, we want our horses to remain sound for a very long time and this comes from removing all inflammation especially in the gut.
Finally, I hope many people read this here but for further updates and comments on “Tiny,” please make a discussion in the forum “No Grain Challenge.” This will help others find the thread because so may horse owners are like you. They want to do the right thing and not sure how to go about it. I am grateful that you came here to learn and find a refreshing point of view. In time, with your experience you will be able to help others as they join and ask the same questions. Doc T