by Tamara Scully
With “millions of metric tons” of canola meal going into the dairy industry, there must be some value to the product. Farmers, by observation, have for years claimed that canola meal is a good source of protein, and readily replaces soy in the dairy cow diet, according to Dr. Essi Evans, of Technical Advisory Services, Inc, in a presentation at the recent 2015 Cornell Nutrition Conference.
Data from the 1980s led to the belief that “canola meal is rapidly degraded in the rumen. The fiber is not digestible. The energy level is very low because the fiber is not digestible,” and the canola meal “takes up a lot of room in the rumen.” Yet despite this conclusion, nutritionists are utilizing canola meal in increasing amounts, she said.
In response to this realization, the Canola Council of Canada took a closer look at the nutritional values of canola meal in dairy cow diets. Their initial findings indicated that dairy nutritionists overwhelmingly found canola meal as being a good or excellent source of protein, with little concern regarding rumen solubility. With imports of Canadian canola meal into the United States doubling in the last decade, the actual feed value of canola meal warranted examination.
“It’s not lagging behind as much as the information would have suggested,” Evans said, and the Canola Council of Canada began to take a closer look at “the true value of canola meal.”
As the Canola Council was reviewing existing research, a 2011 study comparing soybean meal and canola meal found that “the protein value of soybean meal, related to canola meal, was overstated,” Evans said. Instead, milk production increased by 3.4 kg per 1 kg increase in canola meal, yet only increased 2.1 kg per 1 kg increase in soybean meal fed.
The Canola Council established university-based research programs, both in the United States and in Canada, and studies in which canola meal was used to replace other protein sources in dairy cow diets were undertaken in 2013. Across 49 trials where canola meal was substituted, milk yield increased by 1.4 kg when compared to all protein sources, and 0.7 kg when compared to soybean meal.
Canola Council researchers also collected both canola and soybean meal samples from a dozen crushing facilities in Canada. These samples were analyzed during a four year period, 2011-2014, with analysis being performed at the University of Manitoba and the U.S. Dairy Forage Research Center. Rates of protein digested and rumen undegraded protein (RUP) were examined. The results were in line with older data suggesting canola meal had limited nutritional value.
However, some of the samples were also provided to Cornell University, for analysis utilizing newer methods — the Cornell Net Carbohydrate and Protein System (CNCPS 6.5) — to compute the RUP. Using the new method, the RUP value of the canola meal was found to be higher than that of soybean meal. The computations using the CNCPS 6.5 were also in line with other new research findings, showing that at equal amounts of protein, canola meal elevates essential amino acid levels more so than does soybean meal.
It became apparent that the “information in the most commonly used matrixes was not correct,” Evans said, and not that “something was happening in the rumen” to account for the differences in actual trial data versus computed data.
The old method of calculating indigestible neutral detergent fiber (NDF) utilizes a derivative of lignin, of which canola meal contains a high amount. These results indicate that the NDF digestibility of canola meal was low. Results using CNCPS 6.5 methodology was consistent with recent studies putting the digestible NDF of canola meal at approximately 63 percent, much higher than expected when calculating digestible NDF from lignin values.
“Lignin 2.4 is not the same thing as digestible NDF,” Evans said.
Additional research studies have shown that milk urea nitrogen (MUN) concentrations are lower when canola meal is fed. Others show that blending canola meal with distillers grains with solubles (DDGS) “improves the value of the DDGS. The dry matter intake (DMI) is similar, but milk yields increase with the blend,” Evans said.
“What we are seeing is consistently lower MUN values,” Evans said. Additionally, “not a lot of difference in DMI” is seen when canola meal is utilized in the diet. The amino acid profile is the “basic difference between ingredients.”
There potentially could be concern regarding rumen nitrogen requirements not being met due to the substitution of canola meal for other vegetable proteins. While additional research is needed, recent studies suggest that this is not a major issue, according to Evans.
The conclusion from the Canola Council of Canada’s research is that canola meal can be used liberally in lactating dairy cow rations. Old methodology suggesting that canola meal is a poor fed ingredient is no longer valid, and new methodology used to calculate indigestible NDF closely corresponds to observational data from farmers and nutritionists, as well as with the results from recent research trials feeding canola meal.