The results show that canola meal supports milk production as well or better than other plant protein sources, with typical yield improvements between 2 and 4 pounds of energy-corrected milk per cow per day.
As canola meal is more fibrous and has less net energy than soybean meal, some nutritionists have questioned the ability of canola meal to support the needs of cows in early lactation. Early lactation cows are usually in negative energy balance right after calving. Thus, it was not known for sure if the same benefits of using canola meal would be witnessed in early as in mid lactation, as there was no experimental proof to support the use of canola meal at this production stage. Conclusive results are now available from two major feeding trials.
U. S. Dairy Forage Research Center feeding trial
The first experiment, completed in 2016, was conducted under the guidance of Dr. Kenneth Kalscheur and followed the performance of cows from calving through 16 weeks of lactation. The 79 multiparous cows were given either soybean meal or canola meal as supplemental protein sources. In addition, within each protein source, cows received either a high (18%) or low (16%) protein diet, resulting in four dietary comparisons (Table 1).
Within each protein source (canola meal or soybean meal), the differences due to percentage of protein in the diet were not large enough to declare them different. However, there were big differences between the two meals, with the canola meal resulting in greater milk yields and improved feed efficiency.
With the greater yield in milk, there was a concern that reproduction might suffer. No differences in reproductive performance between the two protein sources was observed. However, Kalsheur pointed out that animal numbers were low for this type of analysis.
Kalscheur suggested the amino acid balance provided by canola meal might be instrumental in promoting the additional production and pointed out the importance of the amino acid methionine in early lactation. Canola meal is a rich source of methionine.
University of California feeding trial
The second study was conducted by Drs. Peter Robinson and Nadia Swanepoel at the University of California (UC) in 2019, with a slightly different approach taken. Rather than comparing canola meal to soybean meal, they chose to compare canola meal to a diet where half of the added protein was from soybean meal, with the other half from canola meal. As an added twist, they also added a treatment with extra rumen-protected methionine (Table 2). The diets were formulated to provide 17% crude protein and were fed from week two to 22 of lactation.
As Table 2 shows, milk yield was greatest when the diets contained canola meal. The researchers found that substituting soybean meal for some of the canola meal in the diet reduced milk yield and that this loss in milk could not be fully restored with the added rumen-protected methionine.
The experimenters pointed out the extra milk was not obtained at the expense of body condition, with the losses actually being slightly numerically less when diets contained only canola meal.
There were 403 cows in the study, and with such large numbers, it was possible to evaluate health and reproductive parameters with confidence. The diets had no effect on the numbers of cows culled due to illness or injury. There were likewise no differences for conception rates due to diet. Table 3 shows that conception rates were similar for all of the experimental groups of cows.
It is interesting to note that in the U.S. Dairy Forage Research Center feeding trial, there was an 8-pounds advantage in milk yield per day for canola meal over soybean meal. In the UC study, removing half of the canola meal resulted in a 4-pound per cow per day difference in milk yield. 
This research is part of the Canola AgriScience Cluster, with funding provided through Agriculture and Agri-Food Canada’s Canadian Agricultural Partnership and the Canola Council of Canada, Alberta Canola, SaskCanola and Manitoba Canola Growers. For more information, click here. Additional research is underway to determine the effects of feeding canola meal during the transition period on lactational performance.
PHOTO: Early lactation diets containing canola meal show increased milk yields. Photo courtesy of Canola Council of Canada.
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Brittany Dyck
- Senior Manager, Canola Utilization
- Canola Council of Canada
- Email Brittany Dyck
Essi Evans is a dairy nutritionist with Technical Advisory Services Inc. Email Essi Evans.
