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
Hello Donna,
Nitrate levels can build up in grass pastures, and hence hay, when excessive amounts of commercial fertilizers are used, or they run off from one fertilized pasture into a non-fertilized pasture. Plant stress caused by drought or prolonged cloudy weather can also cause nitrates to rise.
If the levels are too high, they can lead to lowered milk production in pregnant mares, abortions, or reduced growth rates in foals.
Nitrate levels in hay are generally not high enough to be a concern. And toxicities can show up quickly with labored breathing due to a lack of oxygen to the cells. The blood will be brown in color.
Fortunately, toxicities are rare and horses can safely tolerate up to 0.25% nitrates and even up to 0.50% is tolerated in many cases.
About iron, forage (hay and or pasture) in general tends to be high in iron. The average is approximately 180 to 200 ppm. So, for example, if a horse consumes 20 lbs of hay with 200 ppm iron, he will obtain 1816 mg of iron. This is well above the minimum daily requirement of 400 to 600 mg per day for an 1100 lb horse (depending on age, exercise levels, condition, etc.). This is why I often do not recommend adding more iron to the diet in the form of supplementation. And the entire diet should never exceed 500 ppm.
I have an entire section called "Crunching Numbers" in the back of my book that shows how to manipulate percentages, ppm and more that may be helpful.
Thank you for this excellent question.
All the best,
Dr. Getty 
Author of Feed Your Horse Like A Horse
What are safe levels of Nitrate and Iron in hay for horses in PPM measurements? I have read that high levels can be very dangerous for our equine friends is this true?
Secondly, what would make these levels high?
This is a wonderful forum that you offer.......very helpful. Thank you!
Donna
Where are you from? Bayfield, CO