Hay is fed to equines all over the world and year-on-year ranks as the most popular forage for stabled horses both in the United Kingdom and around the world. It is generally cheaper than haylage and, because of its slightly lower nutritional value, it can be fed ad-lib to horses and ponies with less risk of obesity, laminitis and other complications. There are some downsides to feeding hay – for example, because hay is not wrapped like haylage, it can contain more spores and bacteria and because hay is very dry, those spores and bacteria are more likely to become airborne and be inhaled. 

Of all the feedstuffs fed to livestock, hay is the one that can vary the most in terms of quality, containing mould, bacteria and dust. Many horse owners will know the frustration of buying hay and finding a bale that is mouldy all the way through, or one that their horses don’t seem to find it very palatable, or that they have bought hay that is particularly dusty once the bales are open. 

Poor quality hay is not only frustrating and financially painful for horse owners, it can also damage your horse’s respiratory health. Feeding hay containing high levels of bacteria can cause gastro-intestinal upset and contributes to the development of harmful allergies and respiratory diseases. Crucially, some of the most common stable management practices thought to combat dusty hay can actually elevate the levels of harmful bacteria in it.  

The quality of hay and the bacteria levels it contains are dependent on the conditions under which it is grown, harvested, dried and stored. For example, the bacterial community in the soil the hay was grown in transfers to the plant through the root system and can then be ingested by the horse. Unless you are lucky enough to have land and the resources to produce your own forage or know your local supplier very well, then you probably know very little about where it came from. Research is being undertaken to develop a test for bacterial levels in hay but for now all that horse owners can do is to take steps to ensure all other areas of risk are lower. 

There are several way owners can help manage the bacteria levels in their hay – such as storing it carefully to ensure moisture levels stay as low as possible is important to prevent the proliferation of any bacteria that is present in hay. 

Soaking hay must also be avoided at all costs. A practice that is often implemented to help reduce the respirable particles in hay, soaking actually enables bacteria to reproduce, so any impact on the respiratory health of the equine eating it will be far greater. The benefits of the lowered dust levels resulting from soaking hay will be outstripped by the increase in bacterial levels, so alternative methods of dust removal need to be implemented. 

Steaming hay has been shown to both remove the respirable dust particles in hay but also result in the inactivation of any bacteria and spores present. Temperatures in excess of 100°C are reached in the Haygain Steamer which kills the bacteria eliminating the threat. The Haygain Steamer is the only proven method to reduce both respirable dust particles in hay and lower the levels of spores and bacteria in hay, essential promoting good respiratory health in the stabled horse. 

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