Forage is the base of all ruminant diets. Without forage, the ruminant digestive system fails to function properly. It is crucial to producers to understand the quality of forage animals are consuming. This can be done through forage analysis. Forage analyses serve as an invaluable tool for your operation. Learn more about the role they plan on your farm and how to use them to maximize production below.
Importance of Forage Analysis
High-quality forages are the basis of achieving maximum performance in cattle diets. Utilizing high-quality forages allows you to maximize daily gains and milk production. Additionally, it allows the ruminant digestive system to remain healthy and productive.
Anyone who is familiar with animal nutrition knows there are some obvious differences in forage quality.
Often, just the sight, smell and texture of hay, haylage or corn silage will guide us the majority of the way toward the decision of picking a feed for a cow or heifer diet.
Even with obvious differences, there are still subtle differences which perplex even the most knowledgeable producer. For example, what is the difference in hay that looks the same but doesn’t milk the same? Why does one silage perform better than another? Numerous subtle differences cannot be determined by only observation. Therefore, we must turn to a more advanced approach. This approach is a modern, computerized forage-testing laboratory. It can tell us everything we need to know about forage while also redefining forage quality.
The major components of forage can be separated into three groups: protein, carbohydrates and minerals. What we consider fiber is actually part of the carbohydrate group.
All carbohydrate parts are important, but are utilized at different rates. Some are used quickly, others are degraded more slowly and some are barely touched at all and then excreted. Proteins are also handled different ways depending on amino acid profiles.
How Does it Work?
In the past, farmers only needed to know the moisture, crude protein and total digestible nutrients of a forage to make a decision about quality. Today, with the help of laboratory analyses of different nutrient fractions, diet formulations have become more sophisticated. This has allowed nutritionists to meet a ruminant’s nutritional needs on a variety of production levels. It has also reduced the release of unused nutrients into the environment.
Ruminant scientists have determined, within the carbohydrate portion of forages, there are fractions with varying degrees of digestibility. This ranges from fully digestible simple sugars to nearly indigestible lignin. Laboratory procedures are now available to determine rates of acid detergent fiber and neutral detergent fiber.
Forage labs are able to determine how much protein is bound up in both the ADF and NDF, which provides additional information about the quality of the protein.
The new knowledge nutritionists have gained has given them the ability to gain a better understanding of what rumen microbes might do with a given forage. This enables us to determine how much metabolizable energy to expect from a feedstuff’s fermentation. A TDN calculation is no longer sufficient to provide necessary information for ruminant diets.
Knowledge of the different nutrient fractions in forages enables us to predict what the dynamics of the rumen will be and how much milk a cow will produce or what the daily gain of a beef cow will be.
Forage testing has proven to be a useful tool for growers and farmers. It enables them to determine the best way to utilize forages, establish market value of their forages and balance a cost-effective diet in a feeding program.
Understanding Forage Analysis
Understanding analyses is just as important as testing forages. Furthermore, producers often get frustrated because of varying results between labs. Though there can be variability between labs, understanding the results is crucial when comparing.
Before blaming labs for errors, remember acceptable variation is 3 percent of the value. However, this is not to be confused with three percentage points.
Additionally, there are several key terms which are crucial in understanding your results.
- Dry matter: percentage of the sample that is not water. Normal range: 82 to 90 percent
This is the most important determination. If this number is incorrect, everything else will also be wrong.
- Crude protein: nitrogen content times 6.25. Normal range: 18 to 24 percent
This is the most common and dependable test of total protein. High protein is desirable. It can be obtained by harvesting at an early growth stage.
However, protein can be too high as well. Any number above the range means the nutritionist will discount it because it is likely non-protein nitrogen.
- Available protein: This value should be as close as possible to CP and is calculated by adjusting total CP for heat damaged protein, which is unavailable protein and may pass through the animal without absorption or benefit to the animal.
- Soluble protein: percent of CP that is soluble and quickly degraded. Normal range: 35 to 47 percent
- Degradable protein: protein degraded in rumen. Normal range: 65 to 73 percent
- Neutral detergent fiber: Indigestible and slowly digestible components of the cell wall (cellulose, hemicellulose, lignin). Normal range: 33 to 44 percent
NDF increases with plant maturity and will reduce animal intake.
- Acid detergent fiber: least digestible portion of roughage. Normal range: 26 to 34 percent
- Lignin: Indigestible plant component and increases with plant maturity and higher temperatures. Normal range: 6.5 to 8.4 percent.
- Non-fibrous carbohydrates: Lower non-structural carbohydrates and NFC content indicates stress or immaturity; higher levels indicate higher dry matter intake. Normal range: 27 to 34 percent.
NFC is what we should be focusing on instead of fiber. Fiber is a negative except for use in rumen motility. Energy comes from non-fibrous carbohydrates.
- Crude Fat: true fat containing triglycerides. Normal range: 2 to 2.8 percent
- Total digestible nutrients – the amount of digestible nutrients; the energy value of forage. Normal range: 57 to 63 percent.
According to Ray Hicks, University of Georgia Extension, the most important step in obtaining a meaningful analysis is to collect a representative forage sample.
Extreme variation may occur in hay quality even when harvested from the same field. As a result, a separate forage sample should be tested for each hay “lot.” A “lot” refers to a quantity of similar forage. Each cutting should be sampled and marked in storage area where you know which is which.
In terms of equipment, you will need a forage probe, a mixing bucket and sample bags. Furthermore, you should sample forage as near to the time of feeding or sale as possible.
For round bales and baleage, select at least 10 to 20 representative bales. After, select two cores from the round of each side. Next, combine the cores in a bucket and mix them well.
Large round bales should be sampled to the center using a long probe or one with an extension adapter. Angle the probe in an upward direction to reduce the potential for water entering the core holes. In baleage, reseal core hole with tape made for sealing agricultural plastic to prevent spoilage.
Typically, duct tape is known as the fix all. However, it is not sufficient in this case as it will deteriorate quickly in environmental conditions.
When collecting from square bales, select 20 bales and sample from the end at a straight inward line. Then, place the sample to be tested in a plastic bag and label it. Bags should be labeled with your name, lot name, date harvested, and species of grass. After this is done, you can take the samples to your local extension office.
Forage quality is a crucial component of your operation. Though visual signs can be useful, testing forages will always provide the best results. Be sure you understand results and contact your extension agent for further consultation.
Image courtesy of Beef Magazine