Ask the Nutritionist: Dr. Getty's Forum for Equine Nutrition
Welcome to my forum.
Here you will find more than 6 years of questions and my answers. It is searchable and offers a great deal of information.
Currently, I am discontinuing new questions. This may change in the future, but in the meantime, please know that It has been a true pleasure serving you.
Take a look at my Nutrition Library and Tips of the Month for a variety of answers on selected topics. Be sure to sign up for my monthly e-newsletter, Forage for Thought.
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All the best,
Dr. Getty
Hi Robin,
The fact that he is slow to shed is an indication that he may be developing equine Cushing's disease (which is quite common in older horses). Therefore, you are correct in your assessment that he needs a low starch feed.
Performance feeds are typically high in starch and fat, though to evaluate your particular feed, I would need to see the label. Alfalfa is low in sugar and starch, contrary to common opinion, and is a good source of protein -- complementing the overall protein content of his diet to make a high quality protein. So, some alfalfa is fine. But, you'll want to make sure that his feed is designed for his aging needs. Triple Crown Senior or ADM Alliance Senior Glo are both good choices.
I don't like giving horses too much iron because it may increase blood insulin levels. With Cushing's disease, insulin is already elevated (secondarily due to elevated cortisol), so too much iron (more than 500 ppm in the entire diet) is not advisable.
This ought to get you started. If you find that you'd like a customized plan that I would develop for you, please consider setting up an appointment for a personal phone visit. That way, I can go over everything about your horse -- his history, diet, medical treatments, exercise, environment, etc. to come up with a diet that will help keep him healthy for many more years.
All the best,
Dr. Getty 
Author of Feed Your Horse Like A Horse
Where are you from? Bayfield, CO