What The Analysis Means - The best hay or silage evaluation

The best hay or silage evaluation combines visual inspection with chemical analysis. A breakdown of the lab test report that analyzed by a Near Infrared Reflectance (NIR) instrument follows.

Moisture and Dry Matter

  • To compare feeds used the 100% dry matter figures. This means the sample has been oven dried to eliminate all moisture.
  • The dry matter at time of cutting for most forages is 20-25% or 75-80% moisture.
  • Hay baling can be done when dry matter reaches 85% or moisture declines to about 15%. Baled hay will continue to dry in the stack to about 90% dry matter which is considered air dry.

Crude Protein (CP)

Protein is a major nutrition requirement of all animals. Protein is found in leaves much more than stems and is highest in immature forages before they bloom, declining rapidly after blossom or seed head development.

Crude protein ranges and averages for high quality forages are:

Alfalfa

12 - 28%

High Average 20%
Grass

5 - 12%

High Average 10%
Corn Silage

5 - 10%

High Average 8%
Oat Hay

8 - 12%

High Average 10%

Weather Damage or heat damage in storage or stack will reduce protein available for animal digestion.

Fiber

Fiber content is considered by many to be the best single determinant of hay quality. The greater the fiber content, the lower the quality. Higher fiber feeds result in reduced feed intake or animal refusal to eat a full daily dry matter ration. However fiber is required in the animal diet for normal digestion and butter fat production in dairy cows.

Crude fiber which in forages range from 20 to 40 percent has been replaced in some test reports by a more accurate assay as follows:

Acid Detergent Fiber (ADF)

is the assay of choice to estimate digestible dry matter and digestible energy. ADF is expressed as a percentage with the best legume feeds testing less than 31% ADF and top grass hays 33% ADF or less. Early bloom harvested alfalfa will be 31 - 35%, mid bloom 36-41% and full bloom greater than 41% ADF.

As ADF increases digestibility decreases with less milk or gain resulting.

Neutral Detergent Fiber (NDF)

is the best measure of voluntary animal feed intake. NDF is a percent with top quality alfalfa less than 45% ADF and top quality grass less than 55% NDF.

Digestible Dry Matter (DDM)

is the simplest measure of feed quality and is estimated from ADF. The DDM of alfalfa ranges from 50 to 70 percent with better quality alfalfa hay containing more than 62 percent DDM.

Energy or Net Energy

is that part of the feed that creates heat, warmth, milk or fat. Oil seeds and grains are high energy feeds while forages are low energy roughages. Energy levels in feeds are measured in calories or megacalories per pound of feed.

The Net Energy system rates feeds differently depending on how that feed will be used in the animal body either for maintenance or gain such as feedlot feeding or lactation for milk production. The net Energy system is more commonly used for intensive feeding programs such as feedlot finishing of cattle or high production dairy cattle.

Total Digestible Nutrients (TDN)

percentage is an older measure of a feeds ability to provide energy for milk and gain or to keep the animals body warm and maintained. High TDN or high energy feeds include corn 90%, barley 84%, soybean meal 85%, with lower TDN roughages such as alfalfa 55%, grass 55% oat hay 55%, or corn silage 65%. TDN is still a valid measure of a feed nutritional value for average wintering situations such as calf wintering, feeding ewes and beef cows.

Relative Feed Value (RFV)

Is a single number which estimates overall feed quality based on the intake of digestible energy. Minnesota and Wisconsin RFV are slightly different. Feeds with RFV percentage greater than 143 (WI) and 132(MN) are considered prime. Table 1 below indicates RFV values and other data comprising the new market hay grading system of the American Forage and Grassland Council.

Calcium

is a principal mineral utilized by livestock with alfalfa the richest source of forage calcium. Grass hay can be adequate to somewhat deficient depending on the situation and grains are low in calcium. Legume hay ranges from 1.10 to 1.4 percent calcium with gras hay .4 to .7 percent. Corn silage is usually deficient at .18 to .25 percent often requiring supplemental limestone to provide calcium in livestock rations

Phosphorus

is also a principle mineral deficient in nearly all Montana forages. Phosphorus ranges from .20 to .30 in grasses and alfalfa. Grains are high in phosphorus and animals grazing entirely forages will need to have phosphorus supplemented along with salt.