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Measuring alfalfa forage quality

Quick facts

  • Forage sampling is important to maximize forage utilization and animal performance.
  • Ideally forages should be sampled soon after harvest as well as prior to feeding.
  • Visual assessments should be used along with forage testing to evaluate forage quality.

Importance of testing alfalfa quality

Testing alfalfa quality is important whether you plan to keep the forage or sell it. Alfalfa testing will help match the forage to animal requirements, improve ration efficiency and provide a better estimate of quality than visual assessment alone. Testing will also help sell unnecessary forages because potential buyers will have a better idea of quality.

Matching animal requirements

Forage quality should match an animal’s nutritional intake needs. Different classes of livestock have different nutritional requirements. Testing forage quality allows you to better match forage sources to animal requirements. Forage quality can also be used to determine which forages to produce or purchase. More expensive, high-quality forages may not be necessary depending on the class of livestock being fed.

Forage sales

Forage quality sampling is also helpful for forage sales. Testing forages allows you to compare your forage against other sources. Most hay auctions and sales require forage quality testing. Referencing local forage sales and their associated quality can help determine approximately what your forage is worth. Different producers value quality factors differently, and will most likely look at what their forage quality needs are when determining value. A fair price is easier to achieve when both parties involved know the forage quality.

Visual assessment

Visual assessments of hay quality are recommended in addition to a lab analysis. However, visual estimations are no replacement for a forage analysis. Visual assessments should consider factors such as stage of maturity, color, leafiness, foreign material, odor and overall condition.

Visual assessments are also very important to detect potential quality issues that may not show up on a forage quality test. However, visual assessments cannot place an actual value on forage quality factors that are important when feeding hay. The following list includes factors that influence the quality of alfalfa forages:

  • Time of day harvested
  • Stage of maturity at harvest
  • Temperature, rainfall, and climate
  • Variety grown
  • Cutting schedule
  • Harvest techniques
  • Harvest equipment
  • Proper or improper storage
  • Nutrient management
  • Foreign materials
  • Weeds, insects, fungal pathogens, etc.

Improve ration efficiency

While a few of these factors will come up in a visual assessment, the degree of influence on important quality factors such as crude protein (CP) and neutral detergent fiber (NDF) will vary. Under or overestimation of these quality factors will lead to reduced animal production and efficiency. Testing forage quality allows adjustments to be made in feed rations, which increases feeding efficiency of the forage.

When should you test forages?

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Quality designations

The following quality designations have been adopted by the USDA Agricultural Marketing Service. These values are used in hay auction reports as a way to create unique categories for alfalfa hay that can be used consistently across the country.

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Alfalfa terminology definitions

In order to interpret your forage quality report properly, you must understand the different terms used and their meanings. There are many different quality factors that can be reported-all with unique importance. The factors reported can vary depending on which lab you submit your samples and the services they provide. There are also certain quality factors that do not change from lab to lab and the most common ones are listed below.

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Relative Feed Value (RFV) versus Relative Feed Quality (RFQ)

Both Relative Feed Value and Relative Feed Quality are based around the same concept.

(Intake x Energy content)/Standard

The RFV and RFQ standard is set at 100 for full bloom alfalfa, and designed to have similar responses so they could be used interchangeably. However, there are differences in how they are calculated and how they may be used.

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Nathan Drewitz, University of Minnesota Extension agriculture production systems educator and Jared Goplen, University of Minnesota Extension crops educator

Reviewed in 2020

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