What Are You Feeding?

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Nov/Dec 2009 www.horsepower-magazine.com

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What Are You Feeding? Sampling and Analyzing Hay

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By Peggy M. Auwerda, Ph.D. ~ Iowa State University

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a g a z i nsample e Once you receivemthe analyzed back what should you look for?

Look under the dry matter column for crude protein, total digestible nutrients (TDN), ADF, NDF, and calculated RFV. Total digestible nutrients (TDN) estimates the energy content. Forages generally range from 45 to 55% TDN. Hay consists of fiber which is broken down into cellulose, hemicellulose and lignin (see Figure 1 ). Neutral detergent fiber is made up of hemicellulose, cellulose, and lignin. Acid detergent fiber is cellulose

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t Carbohydrate Crude Fiber

t Nitrogen-Free Extracts (NFE) Sugars

t Starch

Amino Acids

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t Non-Nitrogenous Substance

Fatty Acids Fat-soluble Vitamins

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Lipid

Crude Protein

Celluloses (NDF & ADF) Ligin

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Nitrogen

Minerals

Water-Soluble Vitamins

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1) Hay should be sampled from the same lot. A lot indicates the same cutting, field, stage of maturity and harvested within 48 hours. 2) A good, sharp coring m a gdevice a z should i n e be used. The coring device should have an inside diameter of the cutting edge of at least 3/8 inch and no more then 5/8 inch. Dull coring devices causes material to be pushed out of the core. More information can be found in the publication entitled Forage Sampling and Sampling Equipment PM 1098B at the Iowa State University - University Extension website [ https: www.extension.iastate.edu/store/ListItems. aspx?CategoryID=17 ]. m a g a z i n e 3) Walk around the entire stack and sample bales at different heights. For square bales, sample from the end of the bale the full length of the sampler tube. For round bales, sample across the bale at the center. Choose bales at random. 4) Combine the cored samples into a single sample and store in a sealed freezer bag. m a g a z i nair. e Send it Pack samples tightly to exclude to the lab. A list of labs can be found in the publication entitled Forage Testing Laboratories PM 1098A at the Iowa State University - University Extension website [ https: www.extension.iastate.edu/store/ListItems. aspx?CategoryID=17 ].

Ash t Organic Matter

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Listed below are some recommendations when sampling hay:

Moisture t Dry Matter

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HAY (As Is)

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The primary component of a horse’s diet should be forage. Ideally when feeding horses knowing the components of the forage will allow an owner to feed the best grain mix to meet any deficits in the forage. The principle of hay sampling is to obtain a randomly-chosen sample which represents the average composition of the m a g a z i n e hay you are feeding.

Figure 1. and lignin and represents the least digestible portion of the hay. As a hay (plant) matures the amount of fiber will increase. Higher quality hay will have NDF’s between 35-55% and ADF between 22-35% (as fed). Low quality hay will have NDF’s between 5570% and ADF will range between 35-45%. If the hay is 65% or over NDF, it may increase the risk of impaction colic so horses should have plenty of water. Crude protein is determined by measuring the amount of nitrogen in the plant and multiplying it by a conversion factor. Protein level (dry matter basis) in green plants is usually 18-26%. As the hay matures, protein will decrease. Protein requirements for horses ranges between 10-16% with higher amounts required by growing horses. Another factor that may appear on your report is relative feed value (RFV). The RFV is used heavily in the dairy industry. An RFV in the 90’s is sufficient for horses. Grass hays usually score between 75-105 while high-quality alfalfa may score as high as 150.