Zinc Deficiency in Horses
“A healthy outside starts from the inside.” ~Robert Urich
It seems we horse owners will go to great lengths to remedy our horse’s hoof problems, and often to no avail. Oils, creams, supplements–we’ll try it all! Since I began my quest to learn about equine (and then, human) nutrition several years ago, I’ve learned there is a commonly missed, but fantastically simple answer to many of our problems (equine and human, alike)–nutrition! If there’s an ongoing symptom on the outside, something’s likely missing on the inside. In the case of hoof problems–poor hoof quality, brittle, flaking hoof walls, thrush, etc., despite good hoof care–it is most likely due to a zinc deficiency.
According to the National Research Council’s (NRC) nutrient requirements for horses, a mature horse weighing 500 kg (1100 lbs) needs a maintenance amount of 400 mg of zinc per day. Those amounts would increase as work loads increased for the horse. Of course zinc is just one of several trace minerals needed by the horse and it’s imporant to ensure that all trace mineral needs are being met. Copper is another trace that is often deficient in equine diets. If you supplemented zinc alone, without paying attention to copper or the other traces, your problems would still likely exist. But for the purpose of this post–I’ll focus on zinc.
I routinely get my hay and pasture analyzed, and every time, they’ve shown to be short on zinc (as well as other important equine minerals.) Talking with other horse owners who get their forage tested in order to balance their horse’s diet, zinc deficiencies are extremely common.
Added to the common problem of too little zinc is the likelihood of too much iron, another trace mineral, in the diet. (I know, I said I would focus on zinc–but I can’t mention zinc deficiencies without addressing iron!) Too much iron blocks the absorbtion of zinc and can create a deficiency problem as well. The NRC recommends an iron: copper: zinc ratio of 4: 1: 3. The iron levels in my forage are usually so high that I have to add quite a bit of copper and zinc in order to correct the ratio. And since iron is in just about anything the horse consumes (water, grass, hay, feeds, most supplements) this is a bigger problem than most people would believe.
Some signs of a zinc deficiency in horses include:
- poor coat
- mouth ulcers
- flaky skin
- poor hoof quality
- poor fertility
- low immunity
- predisposition to skin infections
- ongoing thrush
So what to do if your horse does indeed have a zinc deficiency? Just buy a commercial hoof/ coat supplement and the problem’s fixed, right? Wrong–well, in many cases! Most of the commercial hoof and/or coat supplements (as well as some commercial feeds) out there contain a good deal of zinc, but I’ve never found one that had enough to cover my horses’ deficiencies. And believe me, I’ve looked! Plus, nearly every one I’ve seen also contains IRON–once again throwing the ratio out-of-whack! I’m not sure why, but it seems that many of these nutritional supplement companies just don’t get it!
So what is the best way to supplement a diet deficient in zinc, or any other mineral, for that matter? Simple–just feed the individual minerals themselves–in the correct amounts and ratio, of course. I order Poly Zinc from a company called Horsetech. There is also a great supplement available called California Trace that has much higher levels of copper and zinc (and no iron to inhibit absorbtion) than other supplements I’ve seen. It can be ordered online. I’ve not used it personally, but heard rave reviews about it. If you don’t want to mess with getting your forage tested or feeding individual minerals–it may be the way to go.
When I learned how to balance my horses’ diets and started supplementing the individual minerals–including zinc– a few years ago, I took some before and after photos. Here are a few. You can see Bob’s coat darkened and lost the washed-out appearance (and no, he’s not in foal!) and Bo, who had terrible feet, showed considerable improvement as well.