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Forage Testing1
M. B. Adjei, J. D. Arthington, and A. R. Blount2WHY TEST YOUR FORAGE?
Forage testing provides useful information about the nutritive value of a forage. This information can be used to adjust the amount of protein and energy supplements that are fed with the forage in order to meet the needs of the animals. If the energy and protein content of the forage are relatively high, the amount of supplement can be reduced, resulting in a cost savings. On the other hand, if energy and protein in the forage are not sufficient to meet the needs of the animals, the producer can feed the correct amount of supplement in order for the animals to perform satisfactorily.HOW TO GET STARTED
Contact one of the certified forage testing labs listed on this web site: http://www.foragetesting.org/Ask the following questions:
- What analyses are available?
- Is chemical or near infrared reflectance (NIR) used?
- What is the cost per analysis?
- How long will it take to receive the test results?
- What are the instructions for collecting, processing, and mailing the sample?
HOW TO COLLECT A SAMPLE
General Instructions
Properly collecting and identifying a sample is very important. A sampling device or tool is needed for collecting hay samples. Several commercial types are available. They usually consist of a tube with a cutting edge on one end and a shank on the other that is fastened in the chuck of an electric drill or hand brace. The sampler is driven into the end of a rectangular bale or the rounded side of a round bale to obtain core samples that are a cross section of the bale. Collect a single core sample from each of 12 bales for a particular lot of hay. Combine the 12 cores into one sample. This will ensure that the sample is representative. The outer layer of weathered round bales should be pulled away before sampling.Each hay cutting, type of hay, etc. should be sampled and analyzed separately. Each hay cutting or lot should be identified and stored separately so that when it is fed it can be matched with its forage test results.
Silage also can be analyzed. Collecting a silage sample may be somewhat more difficult but can be managed. A sample 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, collecting a handful of silage and then covering or resealing the slit with waterproof tape. Collect silage from 5 or 6 places along the bag, mix well, and extract a small sample to send to the laboratory. Immediately place the sample in a plastic bag and seal it. If not mailed right away, place the sample in a refrigerator or freezer. Also, a fair estimate of the nutritive value of the silage can be obtained by analyzing the fresh material as it is going into the silo.
Pasture samples can be collected and analyzed by plucking the forage with your fingers at about the height the animals are grazing it. Scissors or some other cutting device also could be used. If possible, these samples should be dried before sending to the laboratory. If drying is not possible, mail the sample immediately after it is harvested.
Your results are only as good as your sample!
WHAT RESULTS ARE PROVIDED
Results provided may include dry matter, crude protein, total digestible nutrients (TDN), neutral detergent fiber (NDF), acid detergent fiber (ADF), minerals, and some type of quality index. A quality index assigns a numerical value to a hay which then can be used to compare one hay to another. The lab you use may price each analysis separately or some as a group. Often you can select which analyses you want and omit others, thus reducing the cost. Ask the lab to send you information on how to interpret each analysis.HOW TO USE THE RESULTS
The results of forage tests may be compared to the requirements for TDN and protein of different classes of animals. An example for growing beef heifers is in Table 1 . The TDN requirements of heifers increase with higher weights and higher gains. Many residual pastures and hays available during the fall and winter have a TDN concentration of 50% or lower. Forages with lower TDN concentrations also have lower levels of voluntary intake. If the forage alone will not meet the requirements for TDN or protein, then supplements will be needed.If you do not know how to use the results, contact your County Agricultural Extension Office or your nutrition consultant for advice.
Tables
Table 1. Daily TDN and protein requirements of heifers at various weights and gains.1
Heifer
Weight
(lb)
Daily Gain (lb)
Dry Matter Intake
(lb/day)
Daily TDN Requirements
Crude Protein Requirements
lb/day
% of Total Dry Matter
lb/day
% of Total Dry Matter
500
0
0.5
1.0
1.5
9.8
11.0
11.8
12.1
4.9
6.2
7.3
8.3
50.0
56.0
62.0
68.5
.75
.94
1.11
1.25
7.6
8.5
9.4
10.3
700
0
0.5
1.0
1.5
12.6
14.1
15.1
15.5
6.3
7.9
9.1
10.6
50.0
56.0
62.0
68.5
.89
1.11
1.27
1.40
7.1
7.9
8.4
9.0
1National Research Council Nutritional Requirements of Beef Cattle, 1984.
Footnotes
1. This document is SS-AGR-63, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Revised June 2006. This publication is also part of the Florida Forage Handbook, an electronic publication of the Agronomy Department. For more information you may contact M. B. Adjei (mba@ufl.edu). Please visit the Edis website at http://edis.ifas.ufl.edu.2. M. B. Adjei, associate professor, Agronomy Department, Range Cattle Research and Education Center--Ona, FL; J. D. Arthington, associate professor, Agronomy Department, Range Cattle Research and Education Center--Ona, FL, and A. R. Blount, associate professor, Agronomy Department, North Florida Research and Education Center--Marianna, FL; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.
The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
Copyright Information
This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.