Think leaves for more milk

BURLEY — The dairy industry has changed profoundly over the last 50 years, but how growers make hay to feed those cows has been slower to adapt.

Back in 1965, the average U.S. dairy cow produced around 8,000 pounds of milk per year. Today that average is closer to 22,000 pounds per cow each year. University of Wisconsin agronomy professor Dan Undersander worked with a producer who had a cow average 40,000 lbs of milk. And he expects to see cows reach even higher levels of production thanks to today’s genetics.

That is, if producers can realign their two major limiting factors: barn configuration and feed.

While Undersander doesn’t devote much time to worrying about barn configuration, he has spent many hours researching forage quality and how producers can change harvesting techniques to capture more value.

And while Idaho growers often think about cutting hay before bloom to maximize quality, Undersander would like them to think about leaves and dirt.

“Leaf percentage is more important than the maturity of the alfalfa (plant),” he said during a forage conference held earlier this year. “Leaves are what you should be harvesting.”

Standing alfalfa consists of 45 percent leaves and 55 percent stems. His studies have shown that ratio falls to one-third leaves and two-thirds stems after harvest. That’s critical because leaf percentage accounts for 70 percent of the relative feed value, an indicator of quality.

One of the biggest mistakes the forage industry made 40 years ago, in Undersander’s opinion, was adopting (mechanical) hay conditioners. Conditioners put hay in a windrow rather than a wide swath.

“(Mechanical) Conditioners are for drying stems. A wide swath is for drying leaves,” he said. “The two are totally different things.”

Cutting and putting hay in a wide swatch allows the stomates on the leaf surface to remain open and for air to continue to respire from the leaf, allowing the hay to dry faster. In a windrow, the stomates close and the leaf retains moisture. Hay that dries holds onto more starch and sugars, which increases the feed quality. Losing 4 percentage points of starch can cost a grower $6 to $7 per ton when the hay is sold.

“You have the best drying conditions in the world and you take the longest to dry hay because you start in a windrow,” Undersander said. “If you take five to seven days to get the hay off after cutting, it hurts you.”

He suggests picking up a windrow and looking under it before baling. If there’s a layer of leaves, consider raking when the hay is wetter to hold onto more leaves. Every time hay is moved, more leaves are lost. “The wetter it is when you move it and the less you move it, the better off you’ll be,” he added.

Holding onto leaves will also help reduce another drag on quality — ash content. Ash is defined as the total mineral content of forage. Internal ash is naturally occurring minerals found in plants such as potassium or calcium. External ash is essentially dirt. Grass averages around 6 percent internal ash; legumes around 8 percent.

Every 1 percent increase in ash above 6 to 8 percent reduces total digestible nutrients around 1 percent. At 12 percent ash, the average for the Midwest, growers have lost 10 points in relative feed value.

Undersander sees some samples with ash as high as 25 to 27 percent every year. At the level, producer is feeding 1 pound of dirt for every 2 pounds of hay to his cattle, he added.

Keeping ash content to 10 percent is a good goal. Undersander recommends setting the mower height at 3 inches. Going lower will increase tonnage but reduce quality. A rule of thumb is that for every inch the cutter is lowered, you gain a half ton per acre of yield but lose 5 points of relative feed value.

Wheel rakes are one of the most common pieces of hay equipment and the one most likely to put dirt in hay. It’s also most likely to cause leaf loss.

But wide swaths can also lose quality if they are driven over during the haying process and can slow regrowth over a larger portion of the field.

There is no one right way to put up quality hay, Undersander said. But it is important for growers to think about ways to capture more value in an period of flat prices.

from the Twin Falls Times News (www.magicvalley.com)