Tom Bechman, Midwest Crops Editor
(Previously published in Wisconsin Agriculturalist: October 16, 2024)
(Image Source: Hay and Forage Grower)
Pulling forage samples is not an option in Nick Minton’s eyes. It is essential.
“It is where everything begins for feeding livestock,” says Minton, a Purdue animal scientist and director of the Indiana Bull Evaluation Program, based at the Feldun-Purdue Ag Center near Bedford, Ind.
“If you don’t test forages, you don’t have any guidelines for building your ration,” he explains. “You could feed for a month and then judge performance based on if [your livestock] were maintaining body condition or getting thin, but that is backward, in my judgment.
“Forages are a big part of the ration for beef bulls in our testing program, and I want to feed a balanced ration from the beginning. That means I must test feed ingredients for nutrient content, including forages.”
How to sample hay
Achieving a reliable forage test starts with sampling correctly, Minton says. Here are his five basic steps for preparing and evaluating accurate samples:
1. Obtain a hay probe. In some states, county Extension offices have hay probes for loan. Your feed dealer or another input supplier might have a probe for use. They’re available for sale at around $200 per probe.
2. Use the right sample method for the bale type. For round bales, stick the probe into the side of the bales, not the ends. “Your goal is to pass the probe through as many layers of hay as possible, getting a representative sample,” Minton says. “Two probes per bale should be sufficient. If sampling a row of bales from the same cutting, you can skip every other bale down the row.”
For square bales, reverse your method, and sample from each end, not the sides. “This time, you want the probe to pass through as many flakes as possible,” Minton explains.
3. Pull enough samples. Pull at least 20 cores, usually two cores per bale, Minton says. Then mix the material thoroughly. Choose 1 pound of material at random to send to the commercial lab of your choice.
4. Interpret the results. If the lab reports adjusted crude protein, use that figure rather than just crude protein. “Adjusted crude protein is more reflective of the amount of protein available to the animal in the hay, and adjusts for bound or indigestible protein due to excessive heating,” Minton explains.
Also, look at neutral detergent fiber and acid detergent fiber. NDF provides insight into potential feed intake, while ADF tells more about digestibility.
5. Understand terms. TDN stands for total digestible nutrients and is an important comparison between samples, Minton notes. Look at net energy values to get a measure of the same thing, including net energy for maintenance (NEM) and net energy for lactation (NEL). When buying or selling hay, relative forage quality (RFQ) is a common value used. A greater RFQ value indicates higher nutritional value.