Obtaining an Accurate Feedstuff Sample



The nutrient levels of feedstuffs often vary by 10-15%. Book values found in various feedstuff composition tables are useful as averages, but to fine tune rations and address unusual growing conditions or other variables affecting nutrient composition of feedstuffs, feed analysis provides a valuable tool. One of the keys to obtaining an accurate picture of feed quality using feed analysis is to begin with a representative sample. Different types of feedstuffs require different techniques to assure a representative sample.


When taking baled hay samples, it is best to use a sharp edged core sampler. At least 15 individual samples from various places within the lot are needed. At least 50 samples per every 1,000 bales to be fed should be collected. With standard square bales, core samples should be taken from the ends of randomly selected bales. Bales should be selected from different locations throughout the stack to ensure the sample will represent the entire batch of forage. Mix the individual core samples together and use part of this composite as the sample to be analyzed.


Large, round bales require two to three core samples from each side of the bale. Cores from different bales are then mixed together to form the representative sample for analysis. Again, a minimum of 15 samples from 5% of the bales is recommended. If loose or chopped hay is being checked, samples should be taken from various sites.


Silage and High Moisture Grains
Obtaining a representative sample of silage can be difficult for three reasons:

  • Silage varies greatly in moisture content.

  • It is harvested at different times.

  • Storage units do not allow easy access for sampling throughout the unit.

The best way to overcome these difficulties is to take adequate spot samples and to sample often. For tower silos, the unloader should be run until fresh, clean silage is available. Then, catch and mix at least 15 handfuls of silage. Take a one lb sample from this blend.


When sampling a pit or bunk silo, collect at least 20 handfuls of silage at various locations from a freshly cut face of the pile. If it has been more than 12 hours since the last face cut, collect samples from at least six inches below the surface of the cut. Blend these together and take the representative sample from this mixture.


Pasture or Range
When sampling range or pasture, first determine the purpose of the sample. If the purpose of the sample is to determine the composite feeding value of the current forage, samples should be gathered by moving through the area in an "X" or "Z" pattern. Approximately every 50 paces, clip a 12 inch by12 inch area at mowing height. Mix these clippings together to come up with a representative sample. Do not move off the path to cut in a more dense or lush area. Cut only what is available at the predetermined location.


If the sample is being analyzed to determine the value of the forage being consumed by grazing livestock, it is best to first observe the foraging animals closely. This close observation will help in identification of the proper forages to clip. Clip grass samples at the approximate height the foraging animal is grazing. For short-grass range, the clip sample is normally taken at a height of one inch and above. Two inches and above is the typical height for mid and tall grasses. Clip at least six representative areas and mix for each pasture to be analyzed. Discard any foreign material which would not normally be consumed. Grass may be clipped with forage clippers, scissors, knife, or by hand. Clipped samples should be taken on a monthly to bi-monthly basis.


Samples of grain stored in a bin or on a truck are best taken with a grain probe. At least five cores should be taken from various locations in the bin or truck. These samples should be mixed together and a one lb sample bagged, labeled, and sent for analysis. If using a probe is not practical, a common method is to catch at least 12 handfuls of grain at the unloading auger discharge and mix them together to obtain a one lb representative sample.



ADM Alliance Nutrition, Inc. , a wholly owned subsidiary of the Archer Daniels Midland Company