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Dairy study shows canola meal is a key source of methionine, supporting high milk production

In an elaborate study using 530 early lactation mature Holstein cows, researchers in California showed that canola meal stimulated high milk production, likely at least partly due to the methionine that canola meal supplies. The study was published in the June issue of <a href=”″

    target="_blank"><i>Animal Feed Science and Technology</i></a> (Volume 252, Pages 51-63) by researchers Hannah Gauthier, Nadia Swanepoel and Peter Robinson. 

“The two most widely used vegetable protein meals on California dairy farms are canola meal and corn distillers grains (DDGS), with soybean meal being a distant third,” explained Dr. Swanepoel. “Due to recent reductions in the soybean meal price, and given the body of research demonstrating the advantages of feeding canola meal, we wanted to determine the extent of milk yield losses if some soybean meal was added into the ration to replace some of the canola meal.”

The researchers used three diets that all contained 7.5% DDGS, “pretty much the maximum inclusion level used by our dairy farms based on prior studies and on-farm experience,” Dr. Robinson clarified. The researchers evaluated diets that contained 0, 3.5 or 7.0% soybean meal, in exchange for canola meal (Table 1). Total diet protein levels were above NRC requirement levels for all diets. The canola meal control diet represents a combination of canola meal and DDGS that this research group has already determined as an optimal combination to support high milk production.

Table 1. Diets tested in the feeding study (% of dry matter).
 Canola Meal Control3.5% Soybean Meal7.0% Soybean Meal
Canola Meal13.08.23.5
Soybean Meal03.57.0
Crude Protein17.717.817.3

The study showed that performance of the cows for production of milk, milk fat and milk protein (Table 2) was highest on the control canola meal and 3.5% soybean meal diets, and lowest when the soybean meal inclusion level was increased to 7.0%. In addition, the body condition score (BCS) change of the cows showed a net BCS gain on the canola meal diet and a net loss on both soybean meal diets.

Table 2. Milk and component production in the feeding study.
 Canola Meal Control3.5% Soybean Meal7.0% Soybean Meal
Milk yield, lbs/day97.998.693.1
Fat yield, lbs/day3.543.543.32
True protein yield, lbs/day2.902.902.75
Body condition score change, units/30 days+0.05-0.02-0.02

Analysis of blood plasma to determine amino acid profiles among the diets demonstrated an almost 20% decline in methionine levels with the 7.0% soybean meal. This reduction in plasma methionine was in line with levels that have previously been demonstrated to be much lower than desired in lactating dairy cows. “The most likely reason for the decline in performance with the highest dietary addition level of soybean meal was the reduction in methionine as a proportion of metabolized amino acids,” reported Dr. Gauthier.

“It seems clear that canola meal will remain an important protein and amino acid source in dairy rations for some time to come,” said Dr. Robinson.

This research is part of the Canola AgriScience Cluster, with funding provided by Agriculture and Agri-Food Canada, the Canola Council of Canada, Alberta Canola, SaskCanola and the Manitoba Canola Growers.

Media may contact:
Brittany Dyck
Senior Manager, Canola Utilization

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