Question

We have a 12-year-old Quarter Horse mare that is HYPP N/H. We try to find locally grown hay with low potassium, but that’s hard to do. We have access to a hay that is about one-third each of orchardgrass, Kentucky bluegrass, and timothy. Would this be okay to feed her? We also feed rice bran oil (2-3 pumps from bottle), about 1.5 lb (0.7 kg) of low-starch concentrate, and a bit of salt per day, as well as biotin and joint supplements. She is also fed some timothy pellets midday. She has access to pasture most days for one to four hours, depending on the weather. She is ridden one to two hours most days or worked on the longe line for 20 minutes to help manage the HYPP.

Answer

Potassium content of forage can vary widely, so the only way to really know how much potassium there is in a batch of hay is to have it tested. You can find more information about that by reading Determining Hay Quality for Horses or by visiting Dairy One at www.equi-analytical.com.

If you cannot get the forage checked, the next best thing is to slow consumption of the hay. The theory behind slowing consumption is that less potassium will be going into the digestive tract and thus into the bloodstream at one time.

Research conducted recently in Minnesota found that using a hay net with small openings reduced the time it took to consume 1% of the horse’s body weight by over 40%. The researchers used hay nets with 3.2-cm openings (1 1/3 inches). In a boarding situation where you do not have control over the forage, this may be your best solution. The rest of the diet is pretty low in potassium and not as much of a concern as the hay.