Glenn Selk: Forage Testing — A Key Decision Aide

Kansas State University ( Sampling forage with hay probe.
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Hay fields in most areas of Oklahoma are producing an average to above average number of big round bales this summer.  The quality of the hay will be quite variable.  Some will supply a great deal of the nutrients needed to maintain body condition on beef cows this winter.  Other hay will be lacking in protein and energy and will require a substantial amount of supplement to be fed or the cattle will lose weight and body condition during the winter months. 

Forage analysis can be a useful tool to remove some of the mystery concerning the hay that producers will feed this winter.  The out-of-pocket costs of protein and energy supplements are further fuel to this advice.  Testing the grass hays this year for protein and energy content will help the producer design winter supplementation programs most appropriate for the forage supply that is available.  To learn more about matching supplements with available forages, download and read Oklahoma State University Fact Sheet ANSI-3010  “Supplementing Beef Cows.”

There are several good methods of sampling hay for forage analysis.  Most nutritionists would prefer to use a mechanical coring probe made specifically for this purpose.  The coring probe is usually a stainless steel tube with a serrated, cutting edge.  It is 1 inch in diameter and is designed to fit on a 1/2 inch drill or brace.  Cordless drills make these tools quite mobile so that the hay bales to be tested do not have to be hauled to be near an electrical outlet.  The hay samples are place in paper or plastic bags for transfer to a forage testing laboratory.  Cores are taken from several bales at random to obtain a representative sample to be analyzed.   More selections for forage sampling tools can be found on the National Forage Testing Association Website.

Grab samples can also be obtained and tested.  To receive the best information, grab several samples by hand from about 6 inches into the open side of the bale or the middle third of a round bale.  Place all of the sample in the bag.  Do not discard weeds or stems, just because they look undesirable.  They are still part of the hay that you are offering to the livestock.  Be certain to label the forage samples accurately and immediately, in order for the laboratory analysis to be correctly assigned to the proper hay piles or bales.  Obviously the more samples that are sent to the laboratory for analysis, the more information can be gained.  Just as obvious is the fact that as the number of samples increase, the cost of forage testing increases.  Any of the potential nitrate accumulating hays should be tested for nitrate concentration.  Detailed information about collecting hay samples can be found in OSU Fact Sheet PSS-2589 “Collecting Forage Samples for Analysis.”

Samples can be taken to the OSU County Extension office near you and then sent to the OSU Soil, Water, and Forage Testing laboratory in Agricultural Hall on the campus at Stillwater.  The price list below gives some of the options from which producers may choose to best fit their situation.  There are other commercial laboratories available that also do an excellent job of forage analysis.  

Forage Analysis Price list from OSU Soil, Water, and Forage Testing Laboratory


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