Grass seed hay is an intended by-product that is left over from the cultivation of grass for seed. Grass that is mowed when the seed is fully formed is also called grass seed hay. Most of the NSC is in the seed that goes to the seed trade. The long stalks of hay that remain consist mainly of crude fibre (structural carbohydrates) and, dried into hay, form good low-energy roughage for laminitic horses or horses that need to lose weight.
The most commonly cultivated grasses are English and Italian ryegrass, red fescue and tall fescue. Sometimes Kentucky blue grass or timothy grass is also used. Timothy grass and red fescue naturally contain less NSC than the other grass types mentioned. Naturally, this also applies to the hay of these grasses. With a little luck, your forage company can supply you with this hay.
Horses have to chew on this roughage for longer. This ensures increased saliva production, which benefits digestion. The structural carbohydrates also make the intestines have to work harder.
Yet there are also disadvantages to feeding grass seed hay. It contains fewer vitamins, minerals, trace elements and proteins than regular hay. Now that problem is relatively easy to solve by supplementing the shortages.
A bigger problem is the fact that for the production of grass seed grass is used that has been deliberately contaminated with a symbiotic fungus (endophyte), which makes the plant stronger and protects it against insect damage. Unfortunately, this fungus also releases a mycotoxin that is associated with laminitis. It can cause or worsen inflammatory reactions. It also has a vasoconstrictor effect. This can lead to a reduced blood flow in the dermal lamellae and an increase in blood pressure in the hoof.
Whether the grass seed hay is contaminated with endophytes cannot be determined with the naked eye. It is therefore advisable to ask the hay supplier for a document that explicitly states that the hay does not contain endophytes.
A third disadvantage of grass seed hay is that it has almost always been sprayed to prevent diseases in the seed. Then the grass is sprayed before harvest. Fertilizers are often sprinkled lavishly and cultivation takes place on soil exhausted by monoculture. Not exactly the ideal conditions for ‘healthy’ hay. The fact that this hay comes from only one grass species does not benefit the horse either.