September 5, 2017 at 3:32 p.m.
Spring-sown oats, when harvested for forage, aren't really much good in dairy cattle rations, noted University of Wisconsin-Madison Agronomist Ken Albrecht, at the Arlington Agricultural Research Station's agronomy and soils field day near Arlington, Wis. That's because they're relatively low in nutrition and high in neutral detergent fiber (NDF) after they reach the boot stage.
But for oats sown later in the summer, it can be a different story. Research trials were conducted at Arlington and the Lancaster station, with three goals in mind.
One was to see if there were differences in forage yield and quality between oats sown in the spring and those sown during the summer. The second was to see if the response to the season was similar among varieties. Third, researchers wanted to find the best date for sowing oats that would be chopped in the fall.
They found that oats sown in early August and harvested 77 days later yielded an average of three tons of dry matter per acre. That was 13 percent less than oats sown in mid-April and chopped 77 days later.
But the quality of the feed was better. Autumn-chopped oats contained 33 percent more crude protein. And that forage contained 150 percent more water-soluble carbohydrates.
However, the researchers did not find any fall forage yield differences among varieties. But they did find large forage quality differences.
One variety, in particular, looks promising as a fall forage. That one is ForagePlus. Albrecht described it as leafy and late maturing, and with much greater nutritive value than the other varieties we evaluated.
The whole notion of planting oats later in the summer came about when Albrecht and doctoral student Francisco Contreras-Govea were talking about how oats are grown through the winter in Mexico. The result is some very high-quality forage the agronomist said.
Forage oats sown in the summer could open a window for double-cropping. Albrecht mentioned winter wheat, sweet corn and potatoes as possible crops before oats.
An August planting date brings different growing conditions. Temperatures begin to drop, and the amount of daylight lessens. Researchers know, Albrecht said, that both those factors influence forage quality.
Five varieties were involved in the research: Badger, Kame, Esker, Vista, and ForagePlus. The trial took place during 2010 and 2012, with the summer oats sown on three dates - Aug. 2, Aug. 16, and Aug. 30. They were harvested 77 days after planting, in late October.
The shorter days and cooler weather of late summer and fall brought out a greater spread in the maturity of these oats, the agronomist said. But all five varieties yielded three tons of dry matter per acres.
Albrecht said, "I was surprised to see that the yields were almost as great in the late season as they were in the early season."
One factor that aided these trials was rainfall. Rain fell either the same day the oats were sown or the day after. What's more, Albrecht said the crops got enough moisture during the summer.
The quality of the forage from the summer-sown oats was high, making the feed a good fit for dairy cattle rations.
"One of the issues we have with oats for forage is that it doesn't fit very well into dairy rations because of the high neutral detergent fiber concentration," Albrecht said. "Sometimes dairy farmers want more fiber in a ration, to cool it if it's hot."
But summer-sown oats contained much less NDF, and the fiber digestibility was much greater, Albrecht said.
Another good point about summer-sown oats is that the amount of water-soluble carbohydrates in them was higher. That, said Albrecht, will help the feed ferment as silage.
One potential problem is seed oats of ForagePlus can be hard to find. But Albrecht said Vista and Esker - both later-maturing varieties - are almost as good for autumn feed.
For fall forage, oats need to be sown early in August - certainly not after Aug. 15, or yields will start to suffer, Albrecht said. Even waiting until Aug. 15 can cost a ton of dry matter per acre. Planting after Aug. 15 can cost half a ton of dry matter per week.
There are risks with August oats. They include lack of moisture for germination, uncertain harvesting weather in October, and the possibility of a killing frost before the crop can be harvested.
One question that remains is how August oats affect milk production. Said Albrecht, "We need to take a look at this in a controlled feeding trial."
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