Steamers were developed originally in Europe as an alternative to soaking hay, primarily for control of dust/molds. The presence of particles small enough to reach deeply into the lung is known to be a major source of respiratory disease in horses. Hay and straw are the major source of these particles, which include molds, bacteria and yeast. Steaming moistens the hay, settling dust and making it easier to chew and allegedly more palatable. It may also improve digestibility.
Steaming vs. Soaking.
there's no question that soaking hay is a pain in the neck compared to turning on a steamer, but expense and work comparisons aside, there are more things to consider.
A study done in the United Kingdom compared soaking and steaming for their ability to reduce small, airborne particles. Hay was either steamed for 80 minutes, soaked for 10 minutes or soaked for 30 minutes. All three methods reduced airborne particles to the same extent and were highly effective, reducing the particle count by over 90%.
That same study looked at the levels of water-soluble carbohydrate, nitrogen (protein) and several minerals in unsoaked, soaked and steamed hay. As expected from other studies, the largest losses were in potassium and sodium when hay was soaked. Statistically significant, but slight, losses were found for other minerals between unsoaked and soaked hay.
However, several minerals were shown to increase in steamed hay compared to the untreated sample, which is impossible. Therefore, these changes must have been within the error inherent to the testing, or reflected natural variation between the hay bales.
Steaming does kill/sterilize bacteria, fungi and yeast in hay. However, inhaling live organisms isn?t the problem with respiratory irritation. it's because some classes of organisms can be very antigenic and cause allergies to develop or trigger bronchospasm.
Sterilization would be an advantage if the hay was contaminated with harmful bacteria, like Salmonella. EPM-infective sporocysts are also killed by moist heat at the temperatures achieved in steamers (140° F or higher).
The situation with Clostridium botulinum, the organism that causes botulism, is less clear. Moist heat less than 212° F can activate the organism, but a horse producing normal amounts of stomach acid should then kill it. Most hay that contains botilinum toxin has tissues from an animal that was baled into it. If the organism was already active and hay was heated to 176° F, the active toxin will be inactivated.
If you're soaking your hay to lower sugars and make it safer for an insulin-resistant horse, steaming is not for you. Steaming didn't lower the water-soluble carbohydrate content of hay in one study. Efficient extraction of sugars from hay requires large volumes of water that will draw the simple sugars out.
Studies comparing soaking to steaming (steaming 80 minutes, soaking 10 minutes or 30 minutes) found the waste water after steaming hay had a much lower index of bacterial activity than water from hay soaking. Since steaming kills bacteria and soaking pulls soluble sugars out of hay while steaming doesn't, this isn?t surprising.
it's been suggested that the lower bacterial activity in water from hay steaming makes it a preferable method, and that disposing of water from soaked hay is polluting the environment. We think comparing the water from hay-soaking to raw sewage is going a bit far. there's nothing in the hay-soaking water that wasn?t already in or on the hay before soaking, and there's no evidence that water from soaking hay is dangerous.
We steamed and fed grass hays over the winter of 2009-2010 and summer of 2010. The units we used were the Bale Buster Hay Steamer from Happy Horse Products, and both the full bale and half bale from Haygain. These are large pieces of equipment that need a space close to a power outlet.
We had some problems with both products. The Bale Buster?s steam generator cap started to leak from a defective seal after two days (the company replaced it), and we had trouble with our 220-volt electric hook-up and timer in a test barn Georgia in the winter because of unusual snows.
Our testers found that both units failed to come up to the recommended temperature on very cold days. With tightly packed, dusty/moldy bales, even extending the steaming time failed to steam the center of the bales. We found that opening the bales and fluffing up the hay worked better.
This discrepancy in our findings compared to one published study comparing steaming to soaking may be explained by the fact that the study was only steaming 2.5 kg (5.5 pounds of hay), not an entire bale.
Timing is a bit of an issue, too. Waiting 50 to 80 minutes for one bale of hay to be ready is a long time to us. The timer on the Bale Buster helps, though. You can load the unit then set the timer to start steaming in time to have the hay ready when you need to feed.
Freshly steamed hay is safe to handle virtually immediately, but we let it sit a few minutes to ?drip.? None of our test horses dove into the hay, and they all took a few days to get used to it.
In cool weather, leftover steamed hay can be kept in the steamer until you need it at the next feeding. This also helps prevent freezing. But you must feed the hay within 12 hours.
In summer, we advise you to remove the hay from the steamer and put it in a hay bag. If you're steaming to reduce particulate matter for a horse with respiratory issues, don't allow the hay to dry out before feeding.
Although it's an improvement over soaking hay in the winter, we're not sold on the idea that every barn needs a hay steamer. Soaking takes 10 minutes.
However, if we only have one horse that needs special treatment, we?d try the HG500 Half Bale from Haygain, being sure to fluff the hay well. For a barn with more than one horse, Bale Buster?s price and timer feature make it more attractive.
Article by Eleanor Kellon, VMD, our Veterinary Editor.