Forage testing is important, by: Barry Potter


Forage Testing Is Important

Do you test your forages each year? Knowing the nutritional value of your hay or haylage helps farm management in a number of ways. First, it helps you determine if you are meeting your animal’s dietary requirements or whether you need to supplement or avoid overfeeding.

Secondly, baseline forage tests build a profile of your farm field fertility. They augment soil tests to show, for example, if you have enough potassium or phosphorus in your fields.

But are farmers testing their forages routinely? A recent survey of farmers in northern Ontario and northern Quebec indicated that only 16 % of Ontario and 43 % of Quebec respondents routinely test their forages1. While almost 100 % of the Ontario respondents who test their forages go on to balance their feeding programs based on forage test results, only about half the Quebec respondents do so. Interestingly enough, of the farmers surveyed, 20 % of the Ontario farmers indicated they fed no mineral at all to their mature cows and bulls. In these situations where there is a lack of information on the nutritional attributes of available feed and no supplementation, there is risk of mineral deficiency issues.

Does that matter? Why bother testing forages? What can you do with the forage results if you have to feed what you have anyway?

There are many reasons to test forages:

  • To feed the best quality forage to the animals that need it the most, including yearlings, bred heifers, and thin cows
  • To balance delivery of minerals according to animal requirements
  • To provide adequate protein and energy to the various groups of cattle

When should you test your forages?

Dry hay can be tested immediately after harvest. It takes about a month after harvest to complete the “pickling” process (conversion of plant sugars to organic acids) of haylage or silage. At that point it can be sampled. A key difference between haylage or silage that has been freshly harvested versus haylage or silage that has been completely ensiled is the available protein in the forage. Protein can be degraded if the forage is not stored correctly.

From a ration balancing perspective, the amount of moisture in feed is the first parameter to consider. Results will be presented on an as-fed and on a dry matter (DM) basis. If you are comparing feeds, you need to compare on a dry matter basis. This accounts for the moisture difference in various feeds. To illustrate the difference between expressing results on a dry matter basis versus an as-fed basis, here’s an example. A kg of dry hay contains 15 % moisture. A kg of haylage contains 50 % moisture. Both feeds may test at 15 % protein on a dry matter basis, but on an as-fed basis, the dry hay would test at 12.75 % protein (or 127.5 grams of protein per kg) and the haylage would test at 7.5 % protein (or 75 grams of protein per kg). Therefore, because nutrients are found in the dry matter portion of feeds and moisture levels in feeds can be quite variable, nutritionists balance rations on a dry matter basis to anticipate intake of nutrients more accurately.

How do we sample dry hay versus haylage?

With any forage, we are trying to get a sample (about 200 grams) to represent what is grown in a field or a group of bales. It is impossible to get an accurate sample using baled slices of dry hay, so a sample probe is essential. There are many different types of commercially available sample probes. “Push” types must be kept extremely sharp, while “drill” types that use either a hand brace or electric drill are more common. Many newer probes utilize a canister collection chamber that holds the core samples. Make sure the sample probe tip is sharp. Tips may be serrated or straight, as long as they cut cleanly and do not push aside stems particles. Dull probes will push material out of the core. Many probes can be manually re-sharpened. The cutting edge should be at right angles to the probe. The inside diameter should be between 3/8 and 3/4 inch. A smaller diameter may not cut the leaf/stem properly. A probe with a diameter that is too large may result in a sample that is too large for the lab. Avoid open augers that lose leaf particles when withdrawn from the bale. Sample probes should allow penetration 12 to 22 inches into the bales. Research has shown that an extra-long probe is probably not required for large round and large square bales. Take about 20 cores and mix together. From there, take a smaller composite sample (between 200-500 g) to send away to the lab.

For chopped haylage, take about 20 handfuls from different locations from an unloaded pile from the silo, feed bunk (feed must be freshly delivered), or the face of a bunker silo (take good care when taking samples from the face of a bunker). Mix the samples together well and take a smaller sample of the composite (between 200-500 g) to send away to the lab. Remember to keep samples cool and dry and ship to lab as soon as possible. Freeze samples with high moisture content if they cannot be sent immediately.

The other components we are most concerned about with a forage analysis are energy, protein and macrominerals. While energy may be the most limiting ingredient, nutrients work together. If one is not available at the required amount, the rest will not work together to provide the animal with its nutritional needs.

For more information on what you can find in a forage sample, check out the following: Feed Analysis Reports Explained.

Testing forages provides a clear road map to providing the nutrients required for your beef cattle.

1Lafrenier, Carole and Lamothe, Stephanie. 2018. Comparison of cow-calf production in northern Ontario and Quebec. Unpublished.


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