Hay varies in quality more than any other harvested feed.

Evaluating Hay Quality

Hay varies in quality more than any other harvested feed; therefore, having an understanding of the factors that affect this variation is important for making skillful evaluations. Choosing or producing quality hay can be one of the most important economic considerations for livestock managers. Any nutrients not supplied by forage have to be supplemented by concentrates which increases the total feed bill for the operation. High quality hay has high nutrient content (crude protein, digestible energy, and minerals), high intake potential and high palatability. Quality hay should be low but adequate in fiber content, free of dust, musty odor, detrimental weeds, and excessive foreign material.

Stage of Maturity - The stage of plant development at the time of harvest is considered one of the most important and influential factors affecting quality. This factor sets the upper limit of quality and all other factors can only subtract from this quality level. Determining the stage of maturity is easier before the stand is cut; evaluating the maturity of baled hay can be challenging and takes practice.

Leafiness - Leafiness relates to the relative proportions of leaves to stems in the hay and is important since the majority of digestible energy, protein minerals and vitamins are found in the leaves of forage plants. Leafiness is influenced by both harvest/handling methods and stage of maturity.

Color - Hay with a bright green color usually indicates that the hay was cut at a relatively early stage of maturity; rapidly and properly cured, with no damage from rain, molds, or overheating during storage. However, a lack of bright green color does not mean the quality of the hay is necessarily poor. In fact, an early cut, rain damaged hay that is off-color may have a higher quality than a bright green late cut hay.

Odor and Condition - A fresh aroma, free of must and mold, is often associated with green, well cured hay. Usually this hay will be more palatable. Dustiness and musty or moldy smells can reduce palatability and indicate other quality problems. They are often associated with rain damage or poor storage conditions.

The quality of hay you need depends on the needs of your particular animals. Excellent to high quality hay would be appropriate for lactating or finishing animals. Fair to good hay could serve the needs of dry cows, maintenance animals or pleasure horses. Poor quality hay may still be useful for some livestock classes if fed in small quantities unless it has mold or injurious materials that could cause harm.

Forage Quality Terms:

Crude Protein (CP) - Crude protein includes both true protein and non-protein sources of N and is determined by measuring the total nitrogen content of the forage times 6.25.
Acid Detergent Fiber (ADF) - This value refers to the cell wall portions of the forage that are made up of cellulose & lignin. These values are important because they reflect the ability of an animal to digest the forage. As the ADF increases, digestibility of forage decreases along with the energy. On a forage test, ADF is used to calculate total digestible nutrients and net energy of lactation (NEL).
Neutral Detergent Fiber (NDF) - This value is the total cell wall content which is comprised of the ADF portion plus hemicellulose. These values are important in ration formulation because they reflect the amount of forage the animal can consume (intake). As NDF increases, dry matter intake (DMI) will decrease. DMI as a % of body weight = 120/NDF.
Net Energy Lactation (NEL) - The energy value of the feed for milk production, expressed as megacalories (Mcal) per pound of feed. It is calculated from the ADF of the feed. Different forages use different equations to determine NEL, therefore correctly identifying forages is important (i.e. grass, mixed grass/legume, or legume).

From Maryland Cooperative Extension Fact Sheet 644 www.ccerensselaer.org/Libraries/Ag/hay_quaility.sflb.ashx