Thank you for your interest in KER.  If you are referring to the All-Phase mentioned on the KER website, it is not available in the United States, only internationally. However, several of the KER Team Members carry similar products, so be sure to ask your feed supplier for a comparable feed. 

Because your gelding is growing, it is critical that he consume more essential vitamins, minerals, and protein than most adult horses. So, while he may grow on a hay-only diet, to ensure proper, healthy bone growth and development, a supplement of some sort is recommended. I use software called MicroSteed developed by KER to evaluate the nutritional adequacy of a diet. The program uses information about the horse (age, breed, growth rate, etc.) to establish a custom set of requirements specific to that horse.

I found it difficult to meet the energy, protein, and calcium requirements for your gelding when I used timothy pellets instead of alfalfa. Some nutritionists recommended avoiding alfalfa, but for the growing horse, it is an excellent addition to a balanced diet when fed in limited quantities. For illustrative purposes, in the evaluation I used 12 pounds of bermudagrass hay, 6 pounds of alfalfa, and 1 pound of a ration balancer. If your horse is showing signs of physitis, this would be an appropriate diet.

Using timothy pellets, it would take 10 pounds per day as well as 12 pounds of bermudagrass to achieve a similar level of nutrition that the diet with alfalfa provides. I would be surprised if you could get a yearling to eat that many hay pellets.  

The recommendation for a growing horse with developmental orthopedic disease (DOD) is to feed a restricted diet by reducing the amount of starch in the diet, limiting calories, and supplying all the protein, vitamins, and minerals needed by the individual for healthy growth. KER-formulated ration balancers supply these essential nutrients missing in forage-only diets without adding significant amounts of starch. More information on feeding foals to prevent DOD.