by Sally Colby
A field of bright yellow canola is a pretty sight, although most people don’t know what it is when they see it. The terms canola and rapeseed are often used interchangeably, but they aren’t the same crop.
Canola is essentially improved rapeseed. Rapeseed contains high levels of certain compounds that make it unpalatable to livestock. In the early 1970s, after improving the palatability, oil quality and protein level, the crop became known as canola. To be called canola, the crop must test below established levels for erucic acid and glucosinolates; the two undesirable compounds in rapeseed. The term ‘canola’ comes from the term ‘Canadian oil’.
Canada still grows the majority of canola, and the United States is one of its biggest customers. However, farmers in New York, Pennsylvania, Maryland, Virginia and throughout New England have become interested in growing this dual-purpose crop.
Canola is a cool-season crop, and tolerates extended periods of cold, wet weather in spring. It requires well-drained soils with a pH of 6.0 or higher. Farmers can choose to plant either winter or spring canola based on the growing season in their region. Winter varieties are most commonly planted in the east, and have superior yields compared to spring varieties. However, they are prone to winter kill, and must be planted early enough to develop prior to cold weather.
Winter canola can be planted following hay or corn silage if those crops are harvested early enough in the season. Canola can be direct-seeded in late summer, preferably at least six weeks prior to the first killing frost so that plants grow sufficiently to survive through the winter. In general, plants should have six leaves and a strong, pencil-size taproot before the first killing frost.
If canola is seeded at a sufficiently high rate, weeds are not usually a problem. However, canola seedlings are sensitive to weed competition and benefit from clean fields with narrow row spacing. In good growing conditions, the early canopy develops quickly enough to inhibit weed growth.
Winter canola matures close to the same time as winter wheat, so farmers who plant both crops should be prepared to schedule harvest accordingly. Canola is ready for harvest when plants turn from green to a dull straw color, and seeds appear dark brown or black. Shattering of ripe pods is a good indicator that canola is ready for harvest. Seed moisture should measure eight to 10 percent.
For harvest, canola should be cut just below the seed pods to prevent excess crop residue from going through the combine. A good stand of canola yields an average of 40 to 60 bushels per acre, although new varieties have produced higher yields.
After harvest, canola seeds are rolled so that the oil is easier to extract. The rolled seeds are cooked and pressed to remove some of the oil, and seeds are compressed into large chunks. These chunks are processed to remove most of the remaining oil, and meal is the remaining byproduct.
Canola meal tests at about 38 percent protein. Mechanically extracted meal contains residual oil of about six percent (on a dry matter basis), and is suitable in a dairy ration along with soybean meal. According to the Canola Council of Canada, canola meal provides an ideal balance of rumen-degradable protein (RDP) and bypass, or rumen-undegradable protein (RUP) to meet nutrient requirements of dairy cows. The RDP and RUP of canola meal help encourage the production of microbial protein in the rumen, which accounts for as much as 60 percent of the metabolizable protein requirements for milk production.
There is increased demand for canola from plants that press the seeds for oil. However, the issue for most dairy farmers who grow canola will be the distance they must travel to deliver harvested seeds, then getting the meal back to use as a feed supplement. Some farmers are growing canola on a small scale, pressing it on the farm and using the oil as a biofuel. Those farmers can easily feed the meal on their own farm or sell it to other farmers.
Growing canola as a component of dairy feed
by Sally Colby