As mentioned in my last article about the importance of water for horses (click here to read), nitrates are quite a danger to your equine companion. Now, there are many potential nutritional dangers for horses while grazing, and it all depends on the makeup of your pasture, time of year, and even time of day of the grazing periods your horse utilizes. However for this section, I want to strictly focus on nitrates. I will cover many others in the coming weeks.
How exactly are nitrates dangerous to horses? That’s what you really want to know. Nitrate is an “anti-nutrient”, which means it interferes with absorption of necessary minerals in the diet, and can be toxic in large quantities. Nitrates are high in over-fertilized, or drought stricken forages, specifically in your warm season grasses (those are varieties that grow strong during mid June to late July – there are tons, so I won’t list them all here. Familiarizing yourself with the plant species in your area can be highly beneficial to your horses health). It has been shown that nitrates in pastures can increase during times of extreme cloudiness and lack of sunshine as well.
Just to establish a background on where these compounds come from, Nitrogen in the atmosphere is taken in through plant roots and stored in the stems as nitrate (after some very important chemistry magic). As explained in my previous article, these compounds can be found in water too. How do you know if you have dangerous levels in your hay, ensiled feed, or pastures? You must send in samples of your feed, and/or water, to a lab and have an analysis performed. Once you get those test results back, this is what they mean:
(these percentages are based on the DRY MATTER of your feed, in other words, if you took out all the moisture content and completely dried it out)
If concentrations are 0.25% or less (of dry matter), the feed/water is safe
Between 0.25-0.50%, limit this feed to 50% of your pregnant mare’s diet
Between 1.0-1.5%, carefully observe horses fed this feed
At or greater than 1.5%, do not feed to your horses
Can you still use feed with higher levels of nitrates? Sure - within reason. You can dilute the feed to avoid negative effects by mixing with other feeds such as grains or other forages/hays of lower concentrations.
How do you know if your horse is experiencing nitrate toxicity? Well, many toxicities display similar symptoms, so there is no way of guaranteeing your horse has this specific toxicity if it is presenting these symptoms, but they are a sure sign you ought to get your feed and water checked for the possibility of high nitrate levels. Look for reduced feed intake, slowed growth, or inadequate milk production. This is all brought about because nitrates lower the ability of blood to transport oxygen throughout your animal. In extreme cases, high nitrate feeds can cause suffocation, abortion, clumsiness, frequent urination, foaming mouth, and brown urine.
Scary stuff, right? Sure, but there is a silver lining. Just remember that nitrates are a normal compound in plants, and are not necessarily always toxic unless in large quantities, so do not fear turning your horse out to graze simply from reading this information. In fact, horses have a higher tolerance for nitrates than ruminants (such as cattle an sheep), so for that you can thank your equine friend! The point is to always watch for changes in your animal’s behavior, and educate yourself on their nutritional needs, so when changes are observed, you have an idea what to look for and change.