By Essi Evans, Ph.D., E&E Technical Advisory Services

As the dairy industry continues to look for ways to improve their environmental footprint, feed additives are being developed to reduce greenhouse gas (GHG) production. But many of these additives currently require safety certification, so their potential application has been delayed. Additionally, the long-term effects of feeding these compounds are unknown, and the potential increase in feed costs is significant.

Fortunately, there are feed ingredients that can naturally help cows reduce rumen methane emissions. Recent feeding experiments have shown that simply using canola meal as the primary vegetable protein in dairy rations can reduce methane output while also increasing milk yield.

Canola meal increased milk production while reducing methane emissions

Table 1 provides results from six recent feeding trials. The first five studies were conducted with Holstein cows, and the last was conducted with Jersey cows.^1–6 The results for all six trials showed that, on average, energy-corrected milk (ECM) increased by 2.2 lb/cow/day, while methane was reduced by 7.5% and 8.6%, respectively, when expressed as grams/lb of dry matter intake (DMI) or grams/lb of energy-corrected milk.

In a dose/titration experiment (Table 2), there was a linear reduction in methane as the inclusion level of canola meal increased. All diets were formulated to provide 16% crude protein, with canola meal replacing soybean meal on an equal-protein basis.

Table 1. Comparison of methane output for diets in which canola meal replaced soybean meal as the primary source of protein.

¹ SBM = solvent-extracted soybean meal. CM = solvent-extracted canola meal

² 1-Benchaar, et al., 2021; 2-Gidlund, et al., 2015; 3-Holtshausen, et al., 2021; 4-Lage, et al., 2021;

 5-Moore, et al., 2016; 6-Reynolds, et al., 2019

³ ECM = energy-corrected milk

Table 2. Relationship between the level of inclusion of canola meal in the diet and methane output, as determined in one study.¹

¹ Benchaar, et al., 2021

Canola meal also shown to reduce nitrous oxide emissions

Many feeding experiments, as summarized in two recent meta-analyses, have shown that the efficient use of absorbed protein from canola results in lower milk urea nitrogen when compared to other vegetable protein meals.^7,8 Excreted urea nitrogen is rapidly converted to ammonia gas, which can thereby indirectly contribute to atmospheric nitrous oxide. As Table 3 illustrates, urine nitrogen excretion is reduced and milk nitrogen (protein) is elevated as canola meal in the diet is increased.

Table 3. Effect of increasing canola meal in the diet on urinary nitrogen excretion.⁹

⁹ Hassanat, et al., 2020

Images submitted by Canola Council of Canada

These studies show that diet changes, such as the substitution of canola meal for other vegetable proteins such as soybean meal, can have a positive effect on milk production, while at the same time substantially reducing GHG output. There may therefore be economical benefits to reducing GHG production by altering feeding systems and identifying synergies between ingredients and feed additives.

References:

¹ Benchaar C, Hassanat F, Beauchemin KA, et al. Diet supplementation with canola meal improves milk production, reduces enteric methane emissions, and shifts nitrogen excretion from urine to feces in dairy cows. JDairy Sci 2021;104(9): 9645–9663.

² Gidlund H, Hetta M, Krizsan SJ, et al. Effects of soybean meal or canola meal on milk production and methane emissions in lactating dairy cows fed grass silage–based diets. J Dairy Sci 2015;98(11):8093–8106.

³ Holtshausen L, Benchaar C, Kröbel R and Beauchemin KA, Canola meal versus soybean meal as protein supplements in the diets of lactating dairy cows affects the greenhouse gas intensity of milk. Animals 2021;11(6):1636.

⁴ Lage CFA, Räisänen SE, Stefenoni H, et al. Lactational performance, enteric gas emissions and plasma amino acid profile of dairy cows fed diets with soybean or canola meals included on an equal protein basis. J  Dairy Sci 2021;104(3);3052–3066.

⁵ Moore SAE, Kalscheur KF, Aguerre MJ and Powell MJ. Effects of canola meal and soybean meal as protein sources on methane and ammonia emissions of high-producing dairy cows. J Animal Sci 2016;94(Suppl 5):572.

⁶ Reynolds MA, Brown-Brandl TM, Judy JV, et al. Use of indirect calorimetry to evaluate utilization of energy in lactating Jersey dairy cattle consuming common coproducts. J Dairy Sci 2019;102(1):320–333.

⁷ Martineau R, Ouellet DR and Lapierre H. Feeding canola meal to dairy cows: a meta-analysis on lactational responses. J Dairy Sci 2013;96(3):1701–1714.

⁸ Martineau R, Ouellet DR and Lapierre H. Does blending canola meal with other protein sources improve production responses in lactating dairy cows? A multilevel mixed-effects meta-analysis. J Dairy Sci  2019;102(6):5066–5078.

⁹ Hassanat F, Gislon G, Beauchemin KA and Benchaar C. Canola meal in dairy cow diets: effect on nitrogen utilization. J Dairy Sci 2020;103(Suppl 1):288.