Information
that is useful when evaluating hay includes where the hay was grown,
date of harvest, maturity at harvest, method of storage (uncovered,
tarped, barn stored) and bale type and size. Also consider the types
and amounts of preservatives or drying agents used to treat the hay.
Hay
quality can be evaluated using qualitative (sensory) methods or chemical
(laboratory) methods.
Qualitative
evaluations are based on color, odor, foreign material, leafiness,
texture, growth stage and weather damage.
Color: Bright green is the most desirable color for hay. Yellowed hay may
be over-mature or sun-bleached. Dark brown or black hay has probably
been exposed to excessive moisture. Brown hay may have experienced
excessive heat or fermentation.
Odor: Hay should smell fresh. Off-odors such as mildew, mustiness or
rotten odors may reduce palatability.
Foreign
matter: Non-injurious foreign matter includes material that has
little or no feed value but is not harmful to the animal. This includes
nontoxic weeds, straw or sticks.
Injurious
foreign material includes toxic weeds, blister beetles, wire or other
materials that might harm an animal.
Leafiness: Most of the nutritional value of hay is stored in leaves. Hay that
is primarily stems usually has low nutritional value. Stemmy hay can
result from harvesting when plants are too mature or baling when hay
is too dry. Look for hay with a high percentage of soft, non-brittle
leaves. Leaves should be attached to the stems to avoid losses during
handling.
Mold: If mold is present, determine the degree of discoloration from light
cure discoloration to obvious white mold. If mold is present, examine
hay for heat damage or fermentation.
Texture: Stems should be soft and pliable, not brittle. Coarse stems indicate
over-mature plants and low palatability and nutritional value.
Growth
stage or maturity: Most forage plants have an optimal balance
of nutritional value and fiber at the early bloom stage. Alfalfa should
be harvested at 10 percent bloom. Most grasses should be harvested
when seed heads are in the stalk or are just beginning to emerge.
Over-mature forage has decreased protein, palatability and digestibility.
Potential
weather damage: Weather damage often results in discolored hay.
Excessive rain during curing can leach nutrients from the hay.
Chemical
analysis
Laboratory
analysis to determine acid detergent fiber (ADF), neutral detergent
fiber (NDF), relative feed value (RFV), and crude protein (CP) will
help you determine the nutritional value of hay.
Acid
detergent fiber (ADF) is the percentage of highly indigestible and
slowly digestible material in forage. Components that make up the
acid detergent fiber (ADF) include cellulose, lignin, pectin, and
ash. A low ADF is desirable because it indicates more digestible
forage.
Neutral
detergent fiber (NDF) is the percentage of plant cell walls or fiber
in the forage. This includes acid detergent fiber and hemicellulose. A low NDF percentage is desirable because an animal may consume
greater amounts of forage. Feed with extremely low NDF, usually
associated with young forage, can result in insufficient dry matter
intake. This is rarely a problem when feeding hay.
The
relative feed value (RFV) is an index that combines the important
nutritional factors of intake and digestibility. The RFV index ranks
forages relative to alfalfa at full bloom. Alfalfa at full bloom has
an index value of 100.
Crude
protein (CP) reflects the nitrogen content and indicates the capacity
of feed to satisfy the animal’s protein needs. A moderate to high
crude protein value is desirable because it reduces the need for adding
supplemental protein to the animal’s diet.
Forage
Quality Standards Table3
