You have heard it said many times before, "the results are only as good as the sample that was taken". This is a reality for all feedstuffs especially where forage sampling is concerned.
Let's first start with "why" we want accurate results. As dairymen and livestock caretakers we are trying to optimize the performance of our livestock, whether it is producing milk or meat. Without knowing the quality of the feedstuff or forage we are feeding it becomes difficult to balance a ration to insure the animal is receiving the proper amounts of needed nutrients. Secondly, it can be costly. We may be wasting money if we are including unnecessary ingredients based upon poor sample results. Or we may not get the desired performance we are expecting from a ration once it has been deemed balanced. Lastly, a reliable sample allows us to accurately compare one feedstuff to another feedstuff for price comparisons.
So how do you go about obtaining an accurate sample from your forages? Samples should represent each field and each cutting, otherwise known as a sample lot. You will want to consider additional lot separations if there are differences in species, mixture, stage of maturity, rain damage, harvest loss, insect or disease damage and season.
When should you take a sample? This is determined by your desired outcome for the feedstuff. Are you going to keep it and feed it? Then you may want to wait till shortly before you plan to use the feedstuff to allow for any losses that may occur due to storage or handling. If you plan to sell it, you should sample fairly close to the time of sale to guarantee accurate representation of the product being sold. If you are putting it up as haylage or silage then you will want to wait till the product has gone through fermentation and shortly before the time of inclusion in a diet.
Sampling Baled Forages
Tools that you will need to adequately sample dry hay are the following: hay probe, clean bucket, sample bag, and a permanent marker.
If you are testing dried hay samples. This can be done by coring the bales via a hay probe. Hay probes should be placed on the side and coring towards the center in round bales or on the butt ends when coring square bales. You need to core several random bales (approximately 20 cores from small square bales per lot or samples from 8 to 10 large round bales/lot, while still meeting the minimum of total cores). A minimum of 20 cores should be taken overall. Combine the core samples in a pail, mix them together and place the cores into gallon size plastic bag and seal. Properly label the sample with a permanent marker. Learn more about proper methods in theForage Hay Sampling Methodvideo. Hay probes may be checked out at SDSU Extension regional centers.
Sampling Ensiled Forages
Once the ensiled forages have gone through fermentation and you are ready to use the feedstuffs in a ration it will be necessary to obtain an adequate sample.
Tools needed for sampling ensiled forages include a clean bucket, ziplock bag and permanent marker. Once the pile or silo have been adequately opened up you will proceed to collect a 1 to 2 quart sample in a bucket. If you are testing an upright silo, it is recommended to wait until about 2 to 3 feet of silage has been removed. If you are collecting from a pile, collect your sample from the silage that will be fed. Samples should be taken from the morning and evening feedings and mixed in your bucket thoroughly. In between sampling keep the sample in a cold place such as a refrigerator until it is mixed together. Once the sample is combined and labeled with a permanent marker it should again be stored in a cold place, preferably frozen, until it can be mailed or delivered to a lab to prevent damage due to spoilage. Keep in mind, mailing on a Friday versus a Monday and the impact of the sample sitting in a warehouse over the weekend.
There are several labs which then can perform an analysis on the sample to determine the feed quality. For lab contact information please contact your Regional Extension Center. You can either perform a wet chemistry analysis or what is most commonly done is a NIRS (Near Infrared Reflectance Spectroscopy) analysis which is the quickest and cheapest method. Through this analysis you will obtain results for RFV (relative feed value), RFQ (relative feed quality), % dry matter, crude protein, ADF (acid detergent fiber), NDF (neutral detergent fiber), digestible NDF, lignin, crude fat, ash, Calcium, Phosphorus, Magnesium, Potassium, Total Digestible Nutrients, Net Energy for gain, lactation & maintenance, NDF digestibility, and NFC (non-fiber carbohydrate).
The Bottom Line
So why is this important? As we know alfalfa, grass, and corn silage quality will vary greatly based on maturity at the time of harvest, conditions it was put up under, and storage methods. Thus, it has given you a way to value the product based upon its quality and properly utilize it in your rations or when you market it.
Lastly, please remember when you are labeling the sample bag, that you should include your personal contact information: name, address, and phone number along with the name of the sample lot, variety and what the sample is. It is especially important to identify in mixed samples what the mix contains, for example if it is alfalfa and grass hay or is it oatlage versus a perennial Italian rye grass. Knowing this information is important to increase the accuracy of a NIRS sample evaluation.