When you first open hay-test results from a forage laboratory, you’ll be bewildered.
Beef cow nutrition starts with knowing the nutrient value, digestibility and dry matter intake of your hay. Tests can be used to calculate rations or to distinguish good hay from bad.
Look for three things, starting with crude protein, or CP. Next, look at fiber. Those numbers are under neutral detergent fiber, or NDF, and acid detergent fiber, or ADF. High numbers mean more fiber and lower-quality hay. Finally, look at total digestible nutrients, or TDN, a rough indication of energy.
If you hear Justin Sexten speak, he will say sort cows on nutrient needs. Ideally, that’ll be three groups: fat, average and thin. But, he’d settle for two: “fat enough” and “need feed.” Then, sort your hay.
The University of Missouri Extension beef nutritionist says feed the best hay, and any supplements, to those thin cows. The fat cows may live off condition stored on their backs, without supplementation. To cut feed costs, keep cows productive but don’t overfeed.
Back to that confusing hay test. Most reports give 28 sets of numbers in two rows: “as fed” and “dry-matter basis.” To calculate rations and rank hay quality, ignore the first and look at DM. “Always compare dry to dry,” Sexten says. That eliminates half the numbers to study.
CP must be at least 7% to allow rumen microbes to survive and break down fiber into nutrients for the cow. “Anything below 7% means you’ll need protein supplement for fiber digestion in the rumen.”
Sexten doesn’t like giving simple rules of thumb. But, he stands by that 7% CP; it’s basic.
Feeding depends on cows’ condition, lactation and stage of life. Sexten rattles off examples. A fall-calving cow with above-average milk, nursing a calf, going into spring needs 10% to 12% CP, for example. Feeding more will be a waste.
Much depends on cow size and feed intake. Another example: Lactating cows need 2.5% to 2.7% of body weight in DM each day. If we use 2.6% on a 1,300-pound cow, that’s 34 pounds of DM. If the hay is 15% moisture, that is 40 pounds of actual hay. If you have 30 cows needing 40 pounds, that’s a 1,200-pound bale. But, we’re talking intake, Sexten says. If feeding isn’t controlled and cows waste a third of the hay, it’ll take a 1,600-pound bale.
You can see how nutrition guides cost-cutting. Nevertheless, feed management requires math. You must know the hay test results, cow weight, and condition and true weight of bales. It’s not just unrolling bales.
• MU beef nutritionist shares tips on reading hay tests from a laboratory.
• Sort cows on their nutrient needs first, then sort the hay.
• Good feed management requires math and guidelines.
NDF gives an indication of how much a cow can eat. Remember, higher means more fiber, more filling and less nutritious. An NDF of 70 is too high, while 55 is better.
Intake becomes critical for cows in late gestation this winter. Carrying a calf leaves less space for hay in that rumen. If hay is mostly fiber, cows will be short on nutrients.
A pregnant cow needs the best hay. After calving, she can use the high-fiber hay that’s more filling. That’s where sorting cows helps cut feed costs. Move cow-calf pairs away from pregnant cows.
Some tests report “potential feed intake” to help feed the best hay to the right cows. Also, ADF is an indicator of digestibility and is used to derive energy values on the report. That includes TDN, net energy for lactation, net energy for gain, or net energy for maintenance. For simplicity, work with just one of those, Sexten says.
Again, a lower ADF means higher quality hay. An example: That 1,300-pound lactating beef cow with superior milk needs 62% TDN. Same-size cow with average milk needs only 55% TDN.
TDN is relative. A cow can get all her energy from a few pounds of shelled corn. However, she will bawl as if she is hungry, Sexten says. He compares it to eating a plate of fudge, instead of salad. Fudge isn’t filling, so you’ll want more. For the cow, this affects feed costs.
Do the homework
Learning beef nutrition takes a semester course, a thick textbook and computer software. However, there is help available. MU Extension regional livestock specialists can use your hay test to run a program to guide your feeding. So can feed dealers.
This article published in the January, 2010 edition of MISSOURI RURALIST.
All rights reserved. Copyright Farm Progress Cos. 2010.