The main dietary goal in managing an HYPP (Hyperkalemic Periodic Paralysis) horse is keeping total dietary potassium under 1.0%. It is key to look at the total dietary potassium instead of just the hay or just the grain source.
To figure out total dietary potassium (or any other nutrient level), use the following formula:
((Pounds of hay x percent potassium in hay) + (Pounds of grain x percent potassium in grain)) / Total pounds of feed.
For example, if you are feeding 15 lbs a day of a grass hay that measures 1.0% potassium, along with 6 lbs a day of a grain mix that measures 0.8% potassium, then your calculations would be as follows:
((15 x 0.01) + (6 x 0.008)) / 21 = 0.942% total dietary potassium.
Find out the potassium of your hay source, and of your grain, and then you can figure out your horse’s total dietary potassium level.