What's In Your Forage?


By Cheryl Anderson
DTN Staff Reporter

OMAHA (DTN) -- The more you know about the nutrient content of your forages, the better you can meet the nutritional requirements of your animals. And the key to knowing the correct nutrient content of forages is using proper sampling methods, according to Dennis Holthaus, senior beef nutritionist for Hubbard Feeds Inc., in Beloit, Kansas.

Knowing forage nutrient content can be vital to ensure performance, Holthaus said. Without lab analysis, producers could find themselves incorrectly supplementing/filling in deficiencies. The result could be a loss of performance, poor calving rates or even calf mortality. On the other hand, over-feeding supplements can result in money down the drain.

"You need to know what you're feeding to your livestock so you can match the nutrients to the requirements of the animals," Holthaus said.

Testing forages can also help prevent health issues from nitrates. Holthaus said not testing for nitrates can cause abortions or other physical problems in livestock.

Holthaus said an accurate lab analyses of forage is well worth the cost in terms of ensuring correct nutrition and good performance for better profits.

A typical Near Infrared Reflectance Spectroscopy (NIR) analysis costs between $20 and $25 per sample, he said.

"It's not burdensome at all," he said. "It's relatively cheap in comparison to what everything else is."

It is important to use good sampling techniques in order to get an overall average and good reference point of all your forages, without having to test every bale, every load or every silage pile, Holthaus said.

Holthaus said he usually recommends sampling for hay about six weeks after it is put up.

"Hay will go through a sweat, then it will settle out, and you can get a sample," he said. "For silages, I take a pre-ensiled sample so I have a baseline, then I wait until I get the bunker, pit or silo opened back up, so I can get a good sample then as well."


-- For baled hay, Holthaus recommends using a probe capable of taking a core sample at least 14 to 20 inches in depth.

-- Density of the bale and forage type will have an impact on the amount of hay within each six-inch section, but percentage of hay within each section should remain relatively the same. For example, taking a core sample from the outside 12 inches of a bale gives a sample of close to 60% of the hay in that bale. Using a hay probe that is 18 inches in length provides a sample of nearly 80% of the hay in a bale.

-- When sampling from large round bales, producers should take the sample from the rounded side of the bale at a 90 degree angle to the flat side.

-- Samples from large square bales should be taken at a 90 degree angle to the cut end of the bale.

-- Producers should wait at least four weeks to sample hay baled with more than 15% moisture to allow the bales to acclimate to the environment.

-- To ensure high Relative Feed Values (RFV), Holthaus recommends sampling often. Producers should take a probe from 10 to 15 bales for each cutting or lot, with between 10 and 15 bales for each sample. "I just combine them into one sample bag and send it to the lab. The lab will mix that, quarter it and break it down according to protocol," he said.

-- Forages harvested once per season (grass, cereal grains, etc.), as well as straw or forage sorghum hays, both typically produce high yields, so producers should sample every 100 to 150 bales, with 10 to 15 bales per sample.

-- Loosely stacked hay/ground hay piles are difficult to sample. For long stem hay, Holthaus recommends grabbing samples from five to seven stacks, chopping the samples well, then taking a subsample for analysis. This sampling method should be repeated every 25 to 30 bales. For ground hay, samples should be taken from 10 to 12 grab samples from the pile, then mixed and a subsample taken to the lab.


-- For silages in bunkers, pits, driver over piles, or for high moisture baleage, producers should collect samples in a container from several loads through a given time period, then use the quarter method for sampling. The samples should be dumped onto a tarp and mixed with a shovel, the divided into four equal quadrants. Holthaus said two quadrants from opposite corners should be discarded, and the other two quadrants remixed. Repeat the process, then discard quadrants from the opposite corner before combining the remaining samples into a bag for analysis.

-- For baleage samples, producers should use a serrated core sampler, then use the same sampling method as for dry hay.

-- Wait to sample post-ensiling once the pile has been opened up for use and wait until the pile has a minimum of an eight-foot tall silo face to take samples throughout the feed-out phase of the pile, using a loader to pull down silage in several locations and using the quartering sampling method. Holthaus stressed to not approach the face of the pile to take samples and to use a potato fork for digging into packed forage if climbing to the summit of the mount to get a sample. A hole should be cut in the tarp, then a sample taken from several feet down, making sure to repack the silage back and securing the cut tarp section back into place with duct tape.

Cheryl Anderson can be reached at Cheryl.anderson@dtn.com

Follow Cheryl Anderson on Twitter @CherylADTN