The real difference between canola and rapeseed meal

Feed Ingredient Insights

Efstratia Papanikou is a Kansas State (MSc) and University of Illinois (PhD) graduate working as a consultant in the interface between plant and animal science: the feed ingredients. Papanikou can be contacted at [email protected].

The real difference between canola and rapeseed meal

Lea Csontos |

Although both terms refer to the same plant species, they are not necessarily perceived as such by the animal feed industry because of smart marketing.

Rapeseed is an oil- and protein-rich crop that belongs to the Brassicaceae family, being a close relative to mustard and horseradish (of that more anon). Its origins are lost in the depths of time, but it is certain it was cultivated in Europe and Asia before being imported to the American continent.

Today, there are two commercial species of rapeseed: Brassica napus and Brassica rapa, with such minor botanical differences that are practically indifferent for animal feeding purposes. Presumably, the English name of rapeseed was derived from the latter variety perhaps because it was the most common one cultivated in Europe. Incidentally, rapa in Latin means turnips, whereas napus is more closely related to leafy Chinese cabbage, although botanists as always are still debating.

For our purposes, rapeseed is the yellow-flowered crop that dots the fields of regions that are short in daylight and rather cold, such as Canada, northern Europe, and Russia in the northern hemisphere, and parts of Australia and Argentina in the southern counterpart. The oil seeds are dark in color (brown or black), rather hard, and smaller (1-2 mm) than soybeans (up to 10 mm). The main reason for rapeseed cultivation is its oil, with the protein-rich byproduct being used in animal feeds.

Position relative to soybean meal

Rapeseed is the third largest oil crop after soybeans and palm. It has an average yield of 2,000 kg per hectare, which contrasts to around 3,000 kg for soybeans. Taking into account rapeseeds and soybeans contain about 46% and 21% oil in dry matter, respectively, it is apparent that rapeseed is a very interesting plant. Nevertheless, these two appear to thrive in conditions hostile to each other, so there is very little interest in supplanting one with the other. Plus, regions friendly to rapeseed are also inviting to other more lucrative crops, so things are not as simple as they may appear from the above arithmetic.

Main uses as an oil for biodiesel and feed protein source

Originally, apart from some limited use in human cuisine, rapeseed oil was used as lamp oil before being replaced by petroleum. It is used today as a lubricant component, and has other industrial uses similar to those of soybean oil. In Europe, its cultivation has increased significantly in the past two decades because it is used as a biodiesel component and is often heavily subsidized by governments. The remaining animal feed byproduct (rapeseed meal with up to 40% crude protein) is again used for the same purposes as soybean meal, but it requires further qualification because rapeseed contains different, and potentially more harmful, anti-nutritional factors.

The major anti-nutritional factor in rapeseed is erucic acid, not an essential fatty acid, that in original varieties could make up to 50% of lipids in oil. As chronic consumption of large quantities of erucic acid may cause problems in internal organs, it is considered a toxic substance. Thus, in the 1970s, the first efforts began in Canada to develop rapeseed varieties with oil fit for human consumption. Canadian scientists focused on dramatically reducing erucic acid, which resulted in new varieties termed rapeseed zero. Although, erucic acid was not totally eliminated, it is virtually so minimal that is considered relatively safe, hence the term zero. This development enabled the use of rapeseed oil with relative freedom in human and animal nutrition.

The second important anti-nutritional factor for animals is the glucosinolate group of compounds, common in the mustard-cabbage family of Brassicaceae. These are sulfur- and nitrogen-containing compounds that, once seeds are crushed, release pungent (mustard, horseradish) substances that reduce palatability. Thus, when fed at large enough concentrations, feed intake is reduced to the extent that productivity is reduced to unprofitable levels. Therefore, plant geneticists next developed a double-zero variety that contains only up to 30 micromoles glucosinolates per gram in the meal, enabling thus its greater use in animal feeds. Nevertheless, it should be noted that not all newer varieties have the same low levels of erucic acid and glucosinolates.

How the Canadians branded rapeseed 00 as canola

When Canadians ran short of oil for their airplane and marine engines during World War II, they imported rapeseeds as a source of natural lubricant oil. They soon realized that this crop thrived under their conditions and its cultivation was encouraged at a national level. Still, promoting a crop called rapeseed probably placed an impossible task on Canadian marketeers, who came up with an ingenious solution through the use of an acronym from the words of the main organization promoting rapeseed cultivation: CAnadian OiL Association, thus CANOLA. Therefore, originally canola referred only to the double-zero rapeseed of Canadian breeding stock.

Today, double-zero rapeseed varieties dominate worldwide crops. However, this is not necessarily true for all biodiesel varieties. Canadian canola has very strict (lower) standards for both anti-nutritional factors compared with other products. For example, the maximum concentration of erucic acid in Canadian canola is 2%, whereas European Union double-zero varieties have a maximum allowance of 5%. Nevertheless, like other successful products, canola has lost its geographical identity as all double-zero varieties are (erroneously) called canola by feed professionals. This is safe enough for the American continent, but for Europe, any rapeseed/canola product must be qualified before being used. This is important because, while Canadian-type canola can replace 100% of soybean meal – in most cases at least – other double-zero rapeseed varieties require quantification of anti-nutritional factors before being used as freely.