Thursday, August 30, 2012

Hay Forage Analysis

What is Hay Forage Analysis?

Forage analysis of hay provides the nutrient content of the hay that you are feeding to your animals.  Forage nutrient content varies between seasons, locations, cuttings, and storage conditions.  By knowing the nutrient content of the hay, you can better manage the nutrition of your animals for better health and productivity.

Why Should I Perform a Hay Forage Analysis? Nutrient requirements of livestock vary with age, use, season and production status.  Forages generally make up the primary feed of most livestock. Knowing the energy and protein content of forages is important to provide optimum nutrition for your animals.  Forage analysis can also determine mineral levels in the forages.  Different areas of the country have different availability of minerals in the soil and thus result in forages that may or may not meet the requirements of the animal for specific minerals.  Knowing the nutrient content of your forages allows you to better tailor additional supplements to meet the needs of your animals.

How Do I Collect Hay Samples for Forage Analysis?  The most important aspect of collecting a hay sample for forage analysis is obtaining a representative sample of the entire lot of hay.  This means randomly sampling several bales and obtaining a representative sample from several bales.  This often results in a composite sample that is not representative of the hay because of the over representing stems versus leaves.  This is particularly true with alfalfa or alfalfa-mix hays.

Core Samples are the preferred method of sampling hay for forage nutrient analysis.  Quality hay core probes are made of a sturdy metal tube with a sharpened or serrated end to cut through the hay when obtaining the core.  The length of the probe should be at least 14 inches and 18 to 24 inches is preferred.  The probe diameter should be between 3/8 and 3/4 inches.  This will provide about 1/2 pound of hay from 20 samples.  The purpose is to collect a representative sample of stems and leaves.

Obtaining a Quality Sample of Hay for Forage Analysis
  • Sample each "lot" or cutting of hay separately.
  • Obtain core samples from at least 20 bales selected at random throughout the entire lot.  If there are less than 20 bales, take multiple cores from all of the bales until you have 20 core samples
  • Collect core samples from the side of the bale that is most resistant to puncture.  For square bales, sample from the small ends.  For round bales, sample from the side.
  • Drive the entire probe into each bale.
  • Empty the core chamber into the collection canister (multi-bore probes) or into your collection bag (single-bore probes) between each bale.
  • Collect the sample into a 1 quart Ziploc bag.  Squeeze out the air and seal the bag.  Label accordingly.
  • Send the sample to the lab the same day or as soon as possible.
Finding a Sample Probe -

Where Do I Send a Forage Nutrient Analysis?  There are many laboratories across the country that perform forage nutrient analysis.  We use the Montana State University lab.  The best way to ensure a quality analysis is to utilize a laboratory that is certified by the National Forage Testing Association  www.foragetesting.org .  Certification means that this laboratory meets specific quality testing standards for specific areas.

What is the difference between Wet Chemistry and NIR? There are two general methods typically used for forage nutrient analysis, Near Infrared Reflectance Spectoscopy (NIR or NIRS) and Wet Chemistry.  While NIR analysis is less expensive, this method is not considered as accurate as wet chemistry.  NIR may be suitable for determining basic nutrient analysis including DM, CP, ADF and NDF, it is often not suitable for accurate determination of minerals.

What do the forage results mean? The most basic forage nutrient analysis evaluation factors help estimate intake, digestibility, available energy and available protein in the forage.  This is critical for proper feeding to support maintenance needs, growth, and production in the animal.  The results are generally reported on a dry matter basis so that forages can be appropriately compared independent of their moisture content.  Additional tests can also be performed to determine mineral content and sometimes vitamin content of the forage.
  • Moisture:  The percent of the forage that is water.  For hay, this generally runs between 5-15%.  Moisture dilutes out the nutrient value of the forage on an as fed basis.
  • Dry Matter (DM): The percent of the forage that is not water.  For hay, this is typically around 87-95%.  Feeds with lower DM require higher as fed intake to deliver the same amount of nutrients.
  • Crude Protein (CP): An estimate of the protein content based on the total nitrogen of the feed and reported as a percentage.  A normal range in hay is 6-20% on a DM.  For alpacas, the goal would be to have around 12% CP.
  • Neutral Detergent Fiber (NDF):  Measure of the fiber in the feed consisting of hemicelluloses, cellulose and lignin.  These are the carbohydrates that make up the cell wall and structure of the plant material.  NDF predicts voluntary intake.  As NDF increases, there is more fiber to the forage which takes longer to digest and thus decreases voluntary intake.  A normal range in hay is 30 to 60% on a DM basis.  This number for alpaca feed should be less than 50%.
  • Acid Detergent Fiber (ADF): A measure of the cellulose and lignin and leaves out the more digestible hemicelluloses.  ADF is a predictor of digestibility of the hay. As ADF increases, digestibility decreases.  A normal range in hay is 25 to 45% on a DM basis.  Ideally for alpacas, this number has a value less than 30%.
  • Total Digestible Nutrients (TDN): TDN provides an overall estimate of the available energy density of the feed.  It is the sum of the digestible protein, digestible NSC, digestible NDF, and 2.25 times the digestible fat.
  • Relative Feed Value (RFV): A calculated ranking of the feed based on the digestibility (ADF) and the intake (NDF).  The higher the RFV, the better the forage.  RFV is primarily used for evaluating alfalfa hay for dairy cattle.  It will routinely give a low value for grass hays and does not accurately reflect their feed value.  This is because grass hays tend to have a higher NDF (limits total feed intake) than alfalfa but at the same time, they have a lower lignin concentration and thus their fiber is more digestible.  What this does in the RFV calculation is under estimate feed intake and energy value of grass hay, thus under estimating the RFV relative to alfalfa.
  • Minerals: Minerals are critical for the structure and function of tissues in the body. Too little (deficiency) or too much (toxicity) of these mineral can result in poor growth, production and/ or clinical disease.  Mineral content of feed can vary greatly with geographic area.  It is good to evaluate some of the important minerals in the feed sample to help select an appropriate supplementation to match with the hay that you are feeding.  We feed Stillwater Minerals, a supplement specific for alpacas and llamas.  Expensive, but worth the cost to keep our herd healthy. Minerals are typically reported as parts per million (ppm, mg/kg).  Typical mineral analysis might include any combination of the following:
    • Macrominerals
      • Calcium (Ca)
      • Phosphorus (P)
      • Sodium (Na)
      • Chloride (Cl)
      • Magnesium (Mg)
      • Potassium (K)
      • Sulfur (S)
    • Microminerals
      • Colbalt (Co)
      • Copper (Cu)
      • Fluoride (F)
      • Iodine (I)
      • Iron (Fe)
      • Manganese (Mn)
      • Molybdenum (Mo)
      • Selenium (Se)
      • Zinc (Zn)
Using this information.  The most important part of forage nutrient analysis in the energy and protein content of the hay.  This can be used to help determine what production groups of animals will benefit most from this hay and what production groups will need additional energy or protein supplementation.  A general summary of energy (TDN) and protein needs for different production groups of camelids is listed in the table below.

If your hay has a protein or TDN value below the recommendation for the production group, then you will want to either use different hay for that group of animals or consider supplementing those animals with another high TDN or protein supplement, or both.  Feeding the proper hay to specific production groups to meet their dietary needs will help prevent both low and high body condition.  It can also save you in feed costs so that you know what animals specifically need additional supplementation rather than always feeding these supplements to all animals.

Also remember that energy needs increase during times of higher physical activity or cold temperatures (winter).  So, hay that may be doing just fine during the summer months may not provide sufficient nutrition for an animal in the winter.

Camelid TDN and Protein requirements for different sates of production based on 1.5-2.0% BW dry matter intake per day.