Issue 21
Tips on producing hull-less oats

Interest in producing, processing hull-less or "naked" oats increasing

By Dr. Micheal Peel
NDSU Extension Small Grains Specialist





Prairie Grains is the official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain Growers Association,
South Dakota Wheat, Inc., and the Minnesota Barley Growers Association.

Naked, or hull-less, oats have generated substantial interest lately. There is anecdotal evidence of increased milk production when fed to dairy cows, increased feed efficiency in livestock rations, and unique oil properties such as antioxidants and natural emulsifiers. Before producing hull-less oats, there are important characteristics a producer needs to be aware of, and steps that should be taken to ensure successful production. Thus, with the assistance of information from NDSU oat breeder Michael McMullen, let’s look at some of the production points of hull-less oats more in-depth.

Paul, a hull-less oat variety released in 1994 by the NDSU Ag Experiment Station, has been a focal point of the hull-less oat interest. The variety produces about 99% hull-less kernels, a 45-pound bushel weight, 17-19% grain protein, and 7-9% grain oil. The relatively high concentration of high quality protein and oil suggests a more valuable source of protein, and the relatively high oil content, a high metabolizing energy source.

Nutrition studies using Paul oats as a feedstuff with lactating dairy cattle are currently in progress at NDSU, and several other studies have been completed including grower and finishing diets for beef cattle, sheep and swine. In a preliminary dairy study, replacing part or all of the corn and barley with hull-less oats in a mid-lactation diet did not alter milk yield or dry matter intake, but tended to increase milk fat percentage. Further studies are in progress to examine protein requirements when used during early lactation.

Backgrounding beef diets using hull-less oats as a replacement for barley, found feed intake decreased with high levels of hull-less oats, while gains remained constant, resulting in an improved feed efficiency. However, when included in cattle finishing rations, both intake and feed efficiency were somewhat lower. The researchers noted that as a very high energy feed, careful management is required when starting cattle on hull-less oats or when feeding high amounts in the diet, to avoid digestive disturbances.

In swine weaning and finishing feeding trials, Paul oats was substituted for barley using corn at the reference treatment. Replacing half the barley with hull-less oats resulted in average daily gain and feed for pound of gain comparable to the corn-based diet. Swine diets comprised of 50:50 barley and Paul oats produced carcasses equal in quality or better than the standard corn diet.

There is no evidence that Paul oats, or other hull-less varieties, have any advantage over conventional oats when harvested at comparable growth stages for forage.

Producing hull-less oats
On hull-less oat kernels, the hull loosely adheres to and threshes free from the groat during normal harvest operations. Without protection from the hull, the oat germ is vulnerable to injury from rough handling, leading to reduced germination. Seed of hull-less oats seem more vulnerable to fungal infection in the soil. Fungal infection of seed can reduce emergence, particularly in cold wet soils where the duration from planting to emergence is extended. Because hull-less oat seed is more vulnerable to infection by pathogens, a seed treatment is recommended.

Research suggests the optimum seeding rate for hull-less oats is about 1 million live seeds per acre. The variety Paul has approximately 18,000 seeds per pound. A seeding rate of 56 pounds per acre is required to achieve 1 million seeds per acre. Seeding rate should be adjusted for percent germination and expected seedling mortality. The drill calibration table for rye is often useful for the initial setting for hull-less oats. Deep planting should be avoided.

Hull-less oats should be harvested for storage at a moisture content of less than 12%. Cleaner threshing can be achieved when the straw and glumes are dry. The combine should be adjusted to obtain cleanly threshed hull-less kernels while avoiding kernel injury. Kernel injury seems to be minimized by closing the concave and opening the sieves of the combine, so that few kernels are running through the return flow, and most of the kernels are passing through the cylinder only once. Intact seed can then be cleaned after harvest.

Growers have reported that phenoxy herbicides may increase hull retention on hull-less oats. Research suggests Paul is more sensitive to 2,4-D at the three-leaf stage than at later stages, indicating application after the three-leaf stage will result in a higher proportion of cleanly threshed groats.

Without the hull, hull-less oats will invariably yield less than conventional. The hull on conventional oats accounts for 25-30% of the total mass. A relative comparison of conventional and hull-less oat yields can be made by multiplying the yield of the conventional by 0.75. The absence of the hull on hull-less oats is an advantage providing a gain in efficiency of transportation and storage.

Storage problems can occur with hull-less oats if grain is stored at greater than 12% moisture. With higher moisture content, lipase and lipoxygenase enzymes may become active and lead to rancidity. Most moisture testers are not calibrated for hull-less oats.

Although considerable interest in hull-less oats has developed, markets in ND are still limited. The primary market for hull-less oats currently is livestock feed. Market grading standards are not established, but percentage-based hull-less kernels is likely to be an important quality characteristic of the crop.

An effort is under way to establish a hull-less oat processing plant in ND. Organizers of Oat Technologies hope to capitalize on processing and marketing hull-less oats. Informational meetings on forming the venture were held across ND in late March and early April. If there is enough interest, and enough capital is raised, the hull-less oat plant would process oat derivatives including oat protein, oil, and meal. The scope of the project is limited to ND at this point. Interested individuals have until May 10 to submit $250 in seed money toward the development of a business plan. For more information, contact Randy Meidinger, Linton, ND, OT board chairman, ph. 701-254-4225.

Copyright Prairie
Grains Magazine
April/May 1999