It’s well established that the level of ammonia, bacterial toxins, molds and plant-based allergens inside stables can easily reach levels that pose a threat to a horse’s respiratory health. It seems logical that keeping your barn meticulously mucked out is a must. However, a recent German study had surprising results.
The lowest levels of ammonia were found in barns where stalls were only picked free of manure, followed closely by stalls that were not mucked at all. Ammonia level was 1.5 times higher when stalls were mucked out completely on a daily basis.
They also found that ammonia levels didn’t increase over a six-week period of partial mucking and that ammonia levels were lower when horses were bedded on wheat straw rather than straw pellets or wood shavings. The lowest levels of particulate matter in the air was when stalls were not mucked at all.
Bottom Line: The most likely explanation for this result is that wheat straw is a favorable environment for ammonia-consuming bacteria. The particulate matter/dust findings confirm those of other studies that find stall cleaning increases particles in the air. Not mucking stalls probably won’t (and shouldn’t) catch on, but this study does underscore the importance of keeping barns well-ventilated, especially during stall cleaning.