Question

Water-testing on a new property showed a nitrate level of 25 mg/L, which is above the EPA safety standard for humans, according to our local health department. The horses are fed orchardgrass and senior feed. Given the entire diet, does this seem like a reasonably safe amount for a horse that doesn’t have exposure to other high sources of nitrates?

Answer

Concern about nitrate levels in water and feedstuffs intended for horses is generally not as great as for humans or even cattle. Broodmares and young horses, however, might be more sensitive to nitrates, as they act as endocrine disrupters in the horse.

The upper limit of nitrates for livestock is 100 mg/L in the water, so your water is well within acceptable limits. As for the feedstuffs, orchardgrass is not normally a concern in terms of harboring nitrate unless there is excessive application of nitrogen fertilizer or extreme temperature or drought stress. In orchardgrass pasture, nitrates tend to accumulate in the lower part of the stem. If the horses are grazing the tops of the plants, and not consuming stubble near the ground, there would be little concern. Likewise, hay that was not cut very close to the ground wouldn’t be a problem. Senior feed does not have appreciable levels of nitrates.