Forage Sampling Instructions
Forage testing provides information about the nutritive value of forage. The information can be used to adjust the amount and composition of nutritional supplements offered to livestock consuming forage.
Proper sampling of forage is essential to obtain an accurate nutrient or mineral composition, dry matter content, or value of any feedstuff. Correct sampling and analysis is even more important under conditions that might increase feedstuff variability, such as challenging growing conditions.
Forage may be sampled in the pasture, after harvest and baling, or pre- and post-ensilage. All forage and feed samples should be stored in a freezer until shipping for analysis. To minimize the chances for mold formation or spoilage during shipping, ensure your samples arrive at the laboratory as quickly as possible.
Tools
1. Core sampling probe: hand or power operated. A forage probe connected to a drill makes quick work of bale sampling, minimizes leaf loss, and reaches the bale’s interior for a more composite and representative sample. Forage probes can be purchased online or from farm supply stores or borrowed from most CSU Extension offices. The best samples are obtained using a core sampling probe.
2. Core sampling probe: hand or power operated. A forage probe connected to a drill makes quick work of bale sampling, minimizes leaf loss, and reaches the bale’s interior for a more composite and representative sample. Forage probes can be purchased online or from farm supply stores or borrowed from most CSU Extension offices. The best samples are obtained using a core sampling probe.
3. Clean bucket. The bucket is used to collect the individual samples collected from the hay bales.
4. Cloth or plastic bag (gallon Ziplock).
5. Permanent marker
Forage should be sample as near to the time of feeding or sales as possible. Sample processing takes from 5 to 7 business days depending on the tests requested, the methods used, and the overall number of samples received.
Hay quality depends on forage species, stage of maturity, cutting schedule, soil type, soil fertility, presence of weeds, harvest conditions, storage conditions, etc. When sampling, make sure all samples are taken from the same “Lot”. A “Lot” refers to a field of the same or mixed forage species, cutting time, stage of maturity, etc.
Quartering a Sample
Quartering is used to reduce a sample to a smaller, more manageable size in an unbiased manner. Prior to quartering, forage samples collected by hand must be cut into 2- to 3-inch pieces with shears or scissors and thoroughly mixed. Care must be taken to prevent leaf loss. Cored samples can be mixed as is. Pour the entire sample evenly into a pile on a clean surface, preferably paper, plastic, etc. Level the pile and divide into equal quarters (see diagram). Select and save two opposite quarters including the fines. If the sample is still too large, repeat the entire quartering procedure until the proper sample size is obtained and fit in the bag. Always use the quartering method when reducing sample size to obtain a representative sample for analysis.
Sample Collection
Small Square Bales
- Select a minimum of 20 random bales for coring. Collect a core (12 to 18 inches long) using a hay probe from each bale by probing into one end of the bale at a right angle to the surface.
- To hand sample, reach inside each bale and remove a handful of forage. Cut the sample into 2 to 3 inches pieces. Combine all 20 sample in a clean backet and mix thoroughly.
Large Round Bales
- Select a minimum of 20 random bales and collect two cores (12 to 18 inches long) from the circumference of each bale. Combine the cores in a bucket and mix well.
- To hand sample, reach inside each bale and remove two or three handfuls from different locations. Take care not to lose leaves. Combine the samples in a bucket after cutting them into 2- to 3-inch pieces and mix well.
Large Square Bales
- Select a minimum of 20 random bales. Collect two cores (12 to 18 inches long) from each bale, one from each end, by probing at right angles to the surface.
- To hand sample, reach inside each bale and remove two or three handfuls from different locations. Take care not to lose leaves. Combine the grab samples in a bucket after cutting them into 2- to 3-inch pieces and mix well.
Sampling Standing Forage
Standing forage is sometimes tested to determine if it is worth cutting for hay or to determine if grazing animals require supplemental feed. Select at least eight random locations within a field and clip the forage at grazing or harvest height from a one square foot area at each location. In grazing situations try and select the species being selectively grazed. Cut the samples into 2- to 3-inch pieces, combine in a bucket, and mix well. Spread the sample on paper and allow it to air-dry for two to three days. Molding may occur if wet samples are mailed.
Sampling Forage for nitrate
Select bales from hay that is suspected of containing excessive nitrate. Sample the bales using coring procedures outlined previously.
When sampling fields, clip at least 20 random plants at grazing height from the suspected area. Cut into 2- to 3-inch pieces, combine, and mix well in a bucket.
Silage Sampling
Silage samples can be collected from the face of a bunker silo as it is being fed and from the unloader of an upright silo. Bagged silage can be sampled by cutting small slits along the side of the bag and penetrating the hay sampler to collect the material.
Fresh Cut
Sample when moisture content of forage going into the silo is in the range of 64% to 72%. The test results of fresh samples will be similar to those samples after fermentation. Collect two to three gallons of silage from different sections of a load, combine, and mix thoroughly. Save about a quart. Refrigerate or freeze the samples until all loads are sampled. Combine samples, mix thoroughly all load samples, and collect a quart. The final sample should be placed in a cloth forage sample bag and then into a plastic bag to prevent moisture loss during shipping. Freeze the sample prior to mailing and mail samples early in the week to avoid weekend delays and reduce chances of molding.
Upright Silos
If a silo unloader is used, catch at least 12 handfuls of silage as it is discharged from the silo. Do not sample the top or bottom 2 to 3 feet in order to avoid unrepresentative, moldy, or otherwise damaged silage. Place the silage in a clean plastic, mix thoroughly, and reduce the sample size to approximately one quart using the quartering method described above. Place the sample in a forage bag and mail as described for fresh cut samples. If an unloader is not used, the same type of hand grab technique can be used from the silage thrown down for feeding. Silage in the silo can only be sampled to the depths one can reach. The sample only represents that portion of silage. Other parts of the silo may have silage of different quality.
Horizontal Silos
Collect samples using the hand method. Take samples from different areas across the entire surface of the open face of the silo. Combine samples, mix thoroughly, and quarter to reduce the size to about one quart.
Prepare Sample for shipping
Completely fill out the Feed and Forage submission form
Submit approximately ½ gallon of sample
Use a permanent marker to write sample ID or name and contact information on the sample bag. Please ensure that the information on the Forage Submission Form and sample bag are the same
When shipping samples, collect samples later in the afternoon and ship them the same day via overnight delivery
Seal the box with packing tape and mail or drop sample at:
Dropping or Mailing Address:
Soil Water and Plant Testing Lab
Terra Building T-316
4780 National Western Drive
Denver, CO 80216
Payment
Payment is expected at the time of sample(s) submission. With the exception of existing accounts, all other sample submissions must be accompanied with a check or money order made payable to Colorado State University for the total amount due.
For information about purchase orders or payment, contact the SWPTL at soiltestinglab@colostate.edu or 970 491-5061.