Many people still consider hay nothing more than filler, a boredom buster, but it is much more than that. Even if feeding a highly fortified commercial feed, hay will still provide the bulk of your horse’s protein, minerals and vitamins. Hay also has a powerful influence on hind gut health – for better or worse.
The first step in selecting good hay is the physical inspection, and it can tell you quite a lot. Ask permission to open up and closely inspect a bale or two. If you have to, purchase them first.
General appearance includes the leaf to stem ratio. The leaf/blade portion of the hay has the most nutrition and is most digestible. A handful of the hay should bend and compress easily in your hand. The hand-feel is going to be similar to mouth-feel for your horse. Abundant seed heads in a grass hay, or flowers in alfalfa, indicate a very mature cutting which will have lower protein and calories but also lower sugar and starch.
Pass on hay with a lot of weeds or leaves. Although most are not harmful, some are. They also are an unknown nutritionally and weeds often do not cure at the same rate as grasses so their higher moisture can contribute to mold formation. Internal inspection may also reveal sticks or rocks, which means a lot of dirt was baled into the hay. These bales are considerably heavier so some of your hay dollar is wasted.
Color is important, the greener the better. Green color is a good indicator of vitamin A content, as well as vitamins E and C although these are always low. It fades to yellow then brown with age and/or exposure to the sun. Surface discoloration only is not necessarily a deal breaker but should make you ask how old the hay is and if it was kept exposed to the elements (which means the bales could also have been rained on).
Aroma. Good hay has more than just a distinctive smell; it’s a delightful aroma similar to the scent of freshly mowed grass. It is most often called “sweet”, which is impossible to describe but unmistakable once you smell it. The aroma fades with time. An off-odor, musty or earthy indicates mold. This may be present without visible molding.
Dust/Mold. A hay that produces a cloud of particles when you pull apart the flakes or shake a flake should be rejected. The dust may be dirt, which decreases palatability and is a respiratory tract irritant, or mold. When visible, molding causes the center of the bale to be matted together. There will be black, grey or white deposits on the hay. At best, molding robs of the hay of carbohydrate calories and damages protein. At worst, digestive tract irritation and altered digestion with gradual weight loss and poor coat quality also occur. In the most severe cases, damage to internal organs and the immune system could develop. Hay molds are a very potent cause of RAO, recurrent airway obstruction commonly known as “heaves”.
Hay Analysis. The only way to know the calories, protein and mineral levels in your hay is to have it analyzed. There are many web sites which give detailed instruction on how to properly sample hay. You can check with your local state agricultural extension agent on the availability of hay testing in a state lab (least expensive) or check the National Forage Testing Association list for a certified lab: http://www.foragetesting.org/files/2015_Certified_Labs.pdf.
Hay analysis is essential for horses with insulin resistance or equine polysaccharide storage myopathy where intake of ESC (sugars) and starch should be less than 10%. Horses with the problem of passing liquid along with their manure often have low tolerance for fiber and can benefit from hay analysis to make sure the acid detergent fiber (ADF) is below 40% and neutral detergent fiber (NDF) below 60%.
Another important indication for hay analysis is to check for nitrate levels. Nitrate is a naturally occurring precursor to protein in plants which converts to toxic nitrite in the horse’s body. It can accumulate during drought or heat stress and when hay is overfertilized with nitrogen. Several years of manure application to hay fields can increase nitrate levels because manure nitrogen sources break down slowly over time and nitrates accumulate. Check nitrate if hay is known to have been grown under drought/stressful conditions or if the protein level in the hay is higher than expected for the hay type (usually over 12% in a grass hay).
Hay is a large monetary outlay and the major component in your horse’s diet. Selecting it carefully is just good sense.
Eleanor Kellon, VMD