Canola meal: The protein source for today’s dairy cattle

When it comes to feeding dairy cows, vegetable proteins are the major source of supplemental amino acids. Depending on the area, usually more than one is available. Each has advantages and disadvantages when it comes to formulating diets. One source that continues to perform particularly well is canola?meal.??

Table 1 shows the results of head-to head studies comparing canola meal to other vegetable protein sources. As the table shows, canola meal was used as well or better than the alternative meals evaluated in most published studies.??

Table 1.Comparison of milk production (kg) by cows given diets where the major supplemental protein source was supplied by canola meal or another vegetable protein.

Why does canola meal perform so well?

The Canola Council of Canada along with Agriculture and Agri-Foods Canada has been investing in research to try and obtain the answers, and the process is ongoing.?

Older tabular values for canola meal do not coincide with the true feeding value of the meal. There are three reasons for this:

1. Canola is an oilseed that was developed in the 1970’s from rapeseed. While rapeseed still exists in other parts of the world, rapeseed has almost entirely been replaced by canola in North America. The original research occurred with varieties of the meal that are now no longer in use, and some values from that meal persist in tables. Also, nutrient values from rapeseed and canola are often used interchangeably.
2. Canola meal protein is highly soluble. In older formulation systems, soluble protein was equated to degraded protein. In fact, the soluble protein in canola meal is not readily degraded and provides a supply of rumen escape protein.?
3. Canola meal contains more lignin than most oilseed meals. Older formulation systems using lignin to compute indigestible fiber underestimated the digestibility of the fiber component of the meal, which also then resulted in lower calculated energy values.?

Click here to view the nutrient profile and feeding value of canola meal.

A feeding trial involving cows in early lactation, rather than mid or late, lactation was completed by Moore and Kalscheur (2016) in which protein from soybean meal was replaced by protein from canola meal.??These researchers found that milk production was greater (55.7 vs. 51.9 kg) with differences in percentages of milk components. Milk urea nitrogen was lower with the canola meal diet and feed efficiency was improved. Combined, these parameters indicate that protein from canola meal is used efficiently by cows in early lactation.?

There has been much speculation that the amino acid profile of canola meal is responsible for the improvements in nitrogen efficiency noted in many studies. However, the quest to determine the most limiting amino acid is ongoing. Broderick et al. (2015) provided high and low protein diets using either soybean meal, canola meal, or canola meal supplemented with rumen protected lysine and methionine. Although milk production was enhanced with canola meal relative to soybean meal, there was no further improvement found when the two amino acids were added. In contrast, Liu et al. (2016) found greater milk yield with added rumen protected lysine. Swanepoel et al. (2016) investigated milk response to rumen protected phenylalanine. Although the addition of phenylalanine to canola meal was of no benefit to the production of milk or components, more energy was available for body weight gain at the same intakes.?

Rezamand et al. (2016) showed that the fatty acids in as little as 3% oilseed meal can impact gene expression related to inflammatory response. Canola meal contains high levels of oleic acid, which may be more inert than linoleic or linolenic acids.??Fatty acids may become important to future ration formulations.?

In a recent calf study (Hadam et al., 2016) calves were offered starter rations from 15 to 35 days of life. The three rations compared contained either 24% soybean meal, 35% canola meal or 12.5% soybean meal plus 16.5% canola meal.??Average daily gains were lower with all canola meal starter than with the soybean meal or the mixture of soybean meal and canola meal.??It is therefore that using 35% canola meal in starter feeds for calves is not recommended, while a blend of canola meal and soybean meal appears to be acceptable.?

In contrast, canola meal is a suitable ingredient in diets for growing replacement heifers. Suarez-Mena et al. (2015) provided diets to growing heifers that contained 21, 14, 7 or 0% canola meal, with the canola replaced by corn distillers’ grains. Nitrogen retention (protein deposition) decreased as canola was replaced by distillers’ grains. Similarly, Nair et al. (2016) found that feedlot heifers consumed more feed with 10% canola meal than no canola meal in the diet and nitrogen retention was improved with canola meal.??

In conclusion, ample evidence supports the use of canola meal in diets for lactating dairy cattle. Recent findings further indicate that canola meal is well used in early lactation and can be used to support heifer growth. Amounts above 16.5% in calf starter feed may reduce rates of gain. While outdated file values are no longer a concern for formulation, research continues in an effort to learn more about the uses and limitations of this ingredient for dairy animals.?

References available by request.

? Canola Council of Canada Originally Published in Feedstuffs.