Understanding Hay Quality – Part II

Last week in Understanding Hay Quality – Part I, we looked at hay quality standards. This week, we’re looking at maturity, species and variety, leafiness, and harvesting. For more information visit Purdue University’s Hay Information Page, which is the source of the information in this post.
Plant maturity can be determined by the amount of seed heads of grasses or the flowers of legumes present at the time of harvest. As forage progress through seedhead and flower bud development, the concentration of structural carbohydrates and lignin increases and crude protein decreases. The structural carbohydrates are partially digested by the bacteria in the horse’s lower gut, but lignin is not digested at all. For each percent lignin increases, the digestibility of the forage dry matter decreases three to four percent.
Forage digestibility is indirectly measured by determining the level of acid detergent fiber (ADF) in the hay. As the plant matures, ADF increases, and digestibility decreases. Neutral detergent fiber (NDF) increases as the plant matures and is an indirect measure of how readily a forage is consumed. Immature hay is more easily digested by the horse and more readily consumed, and therefore worth more to a horse owner.
Species and Variety
There are two types of hay:

  1. Grass hay: ryegrass, timothy grass, fescue, orchard, redtop, etc.
  2. Legumes. alfalfa and red clover

Legumes are usually higher in protein and calcium than the grasses but not much different in energy or phosphorus levels. Some types of hay bring have potential for feeding problems:

  • Moldy sweet clover hay can contain high levels of dicoumerol, which can tie up Vitamin K and causes the blood not to clot.
  • Broodmares consuming tall fescue that is infected with the endophytic fungus can result in prolonged gestations, thickened placentas at birth, aglactia (lack of milk production), and dystocia (difficult birth).

Parc Éolien de Fresnes-En-SaulnoisLeafiness, Pests, and Foreign Matter
Leaves contain more digestible carbohydrates and protein than stems. As forage plants mature, the leaf to stem ratio decreases. Hay baled at ideal moisture levels of 17 to 20 percent will typically have more leaves because fewer shatter and fall off.
Insects can reduce hay quality potentially leaving behind toxins. Some weeds can also cause problems when present in significant quantity. Some weeds can reduce forage quality while other can be very toxic. Hay should be inspected for the presence of other foreign matter, such as wire or nails. A musty odor can indicate that hay was put up too moist and mold has been allowed to grow in the hay, potentially causing respiratory issues in horses.
Harvesting and forms of Harvested Forages
During harvesting, hay can loose highly digestible sugars and starches, particularly during curing, from the leaching of soluble nutrients during rainfall, and from the physical loss of leaves at harvest. Management techniques that minimize curing time can help minimize loss.
Preservative products consisting have successfully preserved alfalfa hay baled at moisture levels up to 35 percent without affecting intake. Hay should not be packaged when moisture content is greater than 20 percent and an effective preservative is not used.
Forage for your horse can be bought in a variety of forms:

  • Square bales – most commonly used, usually 40-80 lbs.
  • Round bales – usually 800-1200 lbs.
  • Hay cubes – bought in bags, made from coarsely chopped hay.
  • Chopped hay
  • Pellets
  • Silage

Next week, we’ll close out our three-part ha quality series by looking at meeting nutritional requirements, forage testing, purchase, and storage.

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