Ohio State University Extension Bulletin

Horse Nutrition

Bulletin 762-00

Hay Quality

Hay quality is as important as hay quantity. With proper appraisal, hay can be selected that is both safe and worth the money paid for it.

The simplest method of evaluating hay is called the organoleptic (sensory) analysis, which includes:

  1. Maturity – In general, the more mature the forage the less digestible it is and hence of lower nutritional value. This can be evaluated by looking at the coarseness and brittleness of the stems, and the development of the seed head. If legumes are in full bloom or if grass seed heads are large, they are of lower feed value than plants cut at earlier stages of maturity.
  2. Leafiness – The leaves contain most of the protein and nutrients that are highly digestible. Therefore, legume hays that are mostly stems or have a lot of shattered leaves are less valuable than leafy hays.
  3. Condition – This can best be determined by smell and sight to detect mold and dust, and by feel to determine brittleness and heat. All hay develops some heat after it is freshly baled, but if baled too green it will get very hot (more than 100 degrees) and decrease the protein availability. Also if hay is baled too green it is likely to mold or at best become dusty from damage done during the curing process.
  4. Color – Green is ideal but overrated. Green is an indication of Vitamin A content and means that the hay has not been rained on prior to baling. Actually rained-on hay (unless it received a lot of rain over several days) is only slightly lower in nutritive value than hay that was not rained on. That loss in value is usually due to more leaf loss due to more handling to dry the hay for baling.
  5. Foreign Material – Weeds and other trash in a hay sample would lower the value of the hay.

A simple score card for evaluating hay would assign the following values to these five characteristics of hay:

Maturity – 30%
Leafiness – 30%
Condition – 20%
Color – 10%
Foreign Material – 10%

In 1860 Henneberg and Stohman developed a laboratory method to analyze feeds chemically. The method, called Proximate Analysis, divided all feed into six fractions – water, ether extract, crude protein (CP), ash, crude fiber, and nitrogen-free extract. The weakness of this analysis was that although it did analyze a feed for these six fractions, it did not determine how digestible the substances were in these fractions.

In recent years, the Van Soest Detergent Analysis was developed. This method uses the idea that the dry matter of all forage is either cell walls or cell contents.

Cell contents consist of sugars, starches, soluble carbohydrates, pectin, protein, nonprotein nitrogen, lipids, and water-soluble minerals and vitamins. These contents are almost completely digestible (98%).

Cell walls consist of cellulose, hemicellulose, lignin, silica, keratin, waxes, cutin, insoluble minerals, lignified nitrogen compounds, and lignocellulose. In the horse, the cellulose and hemicellulose are partially digestible, thanks to the microbial digestion that takes place in the cecum and colon. The other cell contents are indigestible.

A hay sample is first dried and then mixed with a neutral detergent. This will produce two fractions; one is the cell contents, the second the cell walls (Neutral Detergent Fiber, NDF). The NDF is then mixed with an acid detergent and two additional fractions are produced; one includes the parts that are digestible (acid detergent solubles) and the second is the indigestible portion (Acid Detergent Fiber, ADF).

The lower the ADF and NDF values, the better the quality of the hay. High values indicate that hay has either been cut too mature or baled too green and damaged from excessive heat of fermentation during curing. Table 10 gives expected values for hays of different maturity.

Table 10. ADF, NDF, and CP Values of Hays of Different Maturity
Type of hay CP* NDF ADF
  Late bud
  Early bloom
  Mid bloom
  Late bloom
  Late vegetative
  Late vegetative
* Crude protein will vary about 2% based on soil fertility and hay-making procedures.

Today a chemical hay analysis will include ADF and NDF analysis, dry matter, and crude protein analysis. Thanks to the development of the Near Infrared Reflectance (NIR) method, hay samples can be quickly analyzed for quality. Your local county Extension agent has the information needed to submit a forage sample to local forage testing labs, and also dates and locations for hay auctions in Ohio where this type of analysis is available to the buyer.

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