As equine care-takers, ammonia is something that we battle on a daily basis, whether it is in stalls or in the trailer.

Ammonia is that pungent odor that burns your nose, lungs, and eyes and is a result of urea,
a nitrogen-containing molecule that is present in urine and feces. Urea itself is non-toxic and has no
smell, but once excreted, urea is rapidly converted to ammonia. Ammonia is very irritating to the eyes,
mouth and lungs of both humans and horses and can be very damaging to a horses’ respiratory system.
Long term exposure to high levels of ammonia can reduce the horse’s ability to perform at high levels.

Auxane Maine, a student from Montana State University, completed a summer intern project at
Bluebonnet Feeds which evaluated the ammonia level of 107 stalled horses. Ammonia concentration of
air inside horse stalls was measured at ground level and at nose level. Data collected by Maine showed
that ammonia levels are highest at ground level, which is consistent with published research. It is
important to consider this factor when caring for horses that spend a lot of time laying down or when
keeping foals in a stall. The high concentration of ammonia at ground level can be especially damaging
to the respiratory system of horses that spend a large amount of time near the ground.

To reduce ammonia levels, it is important to pick stalls and trailers often to remove urine and feces, and change bedding often. Ventilation is also a critical factor as ammonia needs a route to escape the confines of the barn. While management practices are the very most important aspect in managing ammonia concentrations in trailers, stalls, and barns, there are also some nutritional components to consider.

One interesting finding from Maine’s project was that stalls of horses fed alfalfa had the same aerial
ammonia concentration as stalls of horses that were fed grass hay when the samples were taken at nose
level. This disputes the common suggestion that in order to reduce ammonia levels in stalls you should
avoid feeding alfalfa. Nutritionally, alfalfa contains a higher level of protein than grass hay. When
horses consume more protein from the diet than they require to meet nutrient demands, they will
excrete the extra protein in the form of urea. As discussed above, urea is rapidly converted to ammonia
after being excreted. 

Horse owners have mistakenly assumed that the high level of protein in alfalfa was directly related to the level of ammonia in stalls, when in reality, the high level of ammonia in the stalls is most likely the result of a diet not being correctly balanced for protein. It is important to consult with an equine nutritionist to know when your horse’s protein requirements are highest and lowest so that you can best manage the feeding program and help avoid excess protein in the diet.

One other nutritional tool that may be used for managing ammonia levels is yucca schidigera. 

Yucca schidigera is a plant native to the high desert which has been demonstrated through research to lower the ammonia concentrations in production agriculture facilities when added to the diet of animals. The addition of yucca schidigera may also be a benefit in equine diets, and some feed companies are now including it in their premium horse feeds. Yucca schidigera may also be beneficial to horses by helping to reduce low level inflammation and provide comfort to horses that suffer from chronic mild arthritis.

Managing ammonia levels in stalls requires a multi-prong approach. There are several products on the
market that are designed to be spread on the stall or trailer floor prior to adding the bedding. Some
studies have shown some of those products to be very effective. As always, you should pick stalls and
trailers frequently and remove all urine trapped under the bedding. Change bedding often and utilize
fans, windows, and door openings to increase ventilation. From a nutritional standpoint, do your very best to match your horse’s total diet to the nutrients that his body requires. Horses that are under a heavy work load or are pregnant, lactating, or growing will require more protein than horses who lead a more sedentary lifestyle. 

Always consult with an equine nutritionist before making changes to your horse’s program.