The common adage “If you cannot measure it, you cannot manage it” is especially true in feeding livestock species.
This article might seem fairly commonplace, however, a large number of people either do not test their feed ingredients, or capture insufficient or incorrect results.
There are several different reasons to test feeds and the timing of testing these feed ingredients becomes very important.
The first and primary reason to test feeds is to quantify nutrient levels of feedstuffs.
These results are then used to determine recommended amounts of energy, protein, vitamins, minerals, and fiber to be able to meet specific operational goals.
There are some ingredients we feed to animals that have fairly consistent nutrient compositions on a dry matter basis, such as grains, but can still be highly variable in the actual dry matter mix of the feed.
Forages on the other hand are essential to test for nutrient composition.
When looking at a bale of hay, you cannot “guess” how much nutrients are included and it is instrumental when feeding cow-calf pairs, dairy cows, growing steers and heifers; in general, any class of animal whose diet consists of greater than 50% as forage.
So, how do we sample forages? This is actually a hard question to answer because it will be different for each operation. Figure 1 highlights some guidelines for sampling different hay depending on source.
When to sample forages: The answer will depend on what you are needing information about and how you plan to use it.
In general, testing forages within a few weeks of feeding is ideal, especially for nutrient composition, but you may have instances in which you would like to test more than once.
And for high-moisture feeds there is a need to sample for dry matter regularly.
In instances when you are worried about toxic compounds such as nitrates, there are several sampling time periods.
For the operation that is harvesting and feeding the potentially high nitrate hay, testing prior to harvest may be beneficial.
Generally, cow-calf operations are more likely to test prior to harvest as they do not have as much equipment to easily dilute the nitrates to a safe feeding level.
When testing for nitrates prior to harvest, I recommend collecting at least 10 plants from around the field. After collecting the plants, cut them into top 1/3, middle 1/3, and bottom 1/3 samples.
Chop each of those segments into smaller ones to be able to put in as much as possible of the plants into a gallon sealable plastic bag that you can then send to the laboratory.
When results are returned, the producer can then estimate cutting height to make forage the safest.
To minimize “sampling error” of exacerbated nitrates, do not collect samples early in the morning, when they will have highest nitrates; do not collect samples on cool, cloudy days; do not collect samples within three days of drought breaking rain; and do not collect samples within two weeks of a nitrogen fertilization event.
All of these will give higher nitrate numbers than you might expect when actually baling. It takes about a week from collection until you get your results back, so plan accordingly.
On the other hand, if you have the capability to dilute concerning nitrate hays and feed, then wait to sample hay until after it is placed into a bale. Then sample 10% of the hay lot.
For round bales, use a hay probe and sample in the middle of the bale going in from the side.
For square bales, sample from the ends. Remember, practice SAFE sampling techniques.
Hay bales that are stacked can shift and fall on the person collecting samples. It is the safest to sample single bales before stacking, but if measuring a stacked hay group, make sure it is secured and you can protect yourself.
If your nitrate forage is going to be made into silage, wait to sample that silage for nitrates after it has fermented; at least Three weeks, but longer is better.
Literature shows that nitrates in properly ensiled silage can be decreased 30-50%, so waiting until after the process is completed provides a better understanding of the forage’s nitrate concentration.
Additionally, waiting until after the silage has fermented to test for nutrient composition is also a more accurate representation of nutrients.
The first week of feeding silage is a good time to collect nutrient composition results.
To sample silage, the recommendation is to use a loader to scoop the feed, then use another container (hand shovel, hand-feed scoop, etc.) to grab at least three scoops from the loader bucket.
Then place that into a sealable plastic bag and freeze. Do this at least three times during the week and composite that week’s samples to send to lab for analysis.
For nutrient purposes, this can be done the first week of feeding with minimal issues for the animals. If very worried about nitrates, then complete this a few weeks prior to feeding.
When to Sample High Moisture FeedsThe recommendation is to sample weekly for dry matter. Dry matter determinations do not have to be completed by a registered laboratory; they can be done at home.
Using a three-week rolling average of dry matter is important to help meet dry matter intake goals for your diet. Moisture can play a large role in underfeeding or even overfeeding cattle.
In a backgrounding example, if you are feeding 650-pound steers a diet that consists of 50% corn silage, if you assumed it was 35% dry matter but it actually tests at 30% dry matter, you have overfed those calves by 4.5 pounds as-fed silage a day.
If you are feeding 100 head of steers, that is 450 pounds extra silage a day, and for a month, 13,500 pounds extra. This has impacts on your pocketbook, inventory management, and marketing.
These cattle will probably have a greater gain than predicted, but if they were pre-contracted, they could take some discounts at the end of the feeding period for being too heavy.
Overall, not knowing what the dry matter of the feed is leads to inefficiencies in your production system.
Every delivery of by-product feeds should be tested for nutrient composition, if they did not come delivered with one.
By-product feed ingredients are highly variable within manufacturing plants, substrates for manufacturing, etc.
One last point – do not fall into the trap of only being concerned about one thing. For example, if you are only worried about nitrates, do not just send a sample in to measure only nitrates.
It takes time and effort to collect a good sample, so take advantage of the fact that a sample can be used to measure a multitude of nutrients.
Nutritionists balance diets for ALL animals based on dry matter, energy, protein, minerals, and vitamins.
Other important measurements that help in dialing down the accuracy of feeding include measures of fiber components, starch, fermentation effectiveness (practically in silages), and digestibility estimates, to name a few.
Many commercial laboratories have “packages” that provide a wide array of nutrient results.
So, is it worth the time and expense to sample you feed? YES! You not only can improve efficiency of production, but in instances of toxic compounds, can save pregnancies and lives.
Jaymelynn Farney grew up in Fort Sumner, New Mexico, where her family had a cowcalf operation. Jaymelynn was very active in 4-H and FFA and because of this after graduating high school she went to El Dorado, KS, to be a member of the livestock judging team at Butler Community College. She completed her A.S. in agriculture degree and then continued her education at Kansas State University in Animal Science. Jaymelynn then went to Oklahoma State University to complete her M.S. in Ruminant Nutrition with an emphasis on receiving calf management. She then returned to Kansas State University to complete her PhD in Ruminant Nutrition, using the dairy cow as the model for how inflammation impacts production. Jaymelynn is focusing her applied research programs on dealing with issues pertaining to cattle producers. She works in the areas of forage management (perennial and annual forages), heifer development programs, stocker management systems, and nutrition. Jaymelynn is using her extension appointment to provide producers with knowledge of new technologies, feeds, and management strategies to improve efficiency of production in beef production systems. Jaymelynn lives in southeast Kansas with her husband, Garet, and works at the Southeast Agricultural Research Center in Parsons.
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