By Steve Barnhart, Department of Agronomy
Oats have been an important crop in Iowa. In addition to being a favored spring-planted companion or cover crop for forage seedings, they have historically been harvested as a cash grain crop. In recent years, as market demands and cropping systems have changed, oats are more often being harvested as hay or silage for livestock.
One of the important decisions producers must make when using oats for forage is when to harvest the crop. This decision has several implications. Early removal of the cover crop from a new forage seeding reduces shade and moisture competition; a benefit to the new forage seedlings. And, harvest timing affects the forage yield and forage feeding value of the harvested corp.
Producers often use visual traits of the developing oat crop when making harvest decisions. Figures 1, 2 and 3 illustrate some of the most commonly used visual guides.
a. 'Boot' stage. The developing seedhead is still in the leaf sheath of the uppermost leaf.
b. 'Milk' stage. The seedhead is green, the developing grain has a liquid, milky color starch.
c. 'Dough' stage. The seedhead color is changing from green to yellow; the grain starch is changing from soft to hard consistency.
The forage yield and forage feeding value of the harvested crop change as the oat plant matures through its growth stages. (See Figure 2 and Tables 1 and 2). Note that these changes occur relatively quickly. Producers are encouraged to consider the nutrient requirements of the livestock being fed as a guide to timing of their oat forage harvest.
The harvested yield of oats forage increases rapidly with increasing maturity until early dough stage.
For lactating dairy cattle, oat forages should be harvested as the first grain heads appear in a field (late boot stage). Oat forage at this stage will provide a feed with more energy and similar protein levels to late-bud alfalfa and similar energy but higher protein content than corn silage. Many producers harvesting oats for feeding to gestating beef cows will delay harvest until the dough stage, to gain slightly more forage yield.
Stephen K. Barnhart is the ISU Extension forage agronomist. He can be contacts by phone at 515-24-7835 or by e-mail at firstname.lastname@example.org.