Holtshausen Lucia, Benchaar Chaouki, Kröbel Roland, Beauchemin Karen A
Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB T1J 4B1, Canada.
Sherbrooke Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, QC J1M 0C8, Canada.
Animals (Basel). 2021 May 31;11(6):1636. doi: 10.3390/ani11061636.
Soybean meal (SBM) and canola meal (CM) are protein supplements used in lactating dairy cow diets and, recently, an enteric methane-mitigating effect (i.e., lower Y value) was reported for CM. Before recommending CM as a greenhouse gas (GHG) mitigation strategy, it is necessary to examine the net impact on total GHG emissions from milk production. The objective was to determine whether using CM rather than SBM in lactating dairy cow diets decreases GHG per kilogram of fat and protein corrected milk (FPCM), and whether the decrease depends upon where the meals are produced. Cradle to farm-gate life cycle assessments were conducted for a simulated dairy farm in eastern (Quebec) and western (Alberta) Canada. Scenarios examined the source of protein meal, location where meals were produced, and the methane-mitigating effect of CM. The Holos model was used to estimate GHG emissions from animals, manure, crop production, imported feeds, and energy use. GHG intensities (COe/kg FPCM) were 0.85-1.02 in the east and 1.07-1.11 in the west for the various scenarios, with enteric methane comprising 34 to 40% of total emissions. CM produced in western Canada with a low up-stream emission factor and low Y value reduced COe/kg FPCM by 3% (western farm) to 6.6% (eastern farm) compared with SBM. We conclude that using CM rather than SBM in the diet of lactating dairy cows can be a GHG mitigation strategy depending upon where it is produced and whether it decreases enteric methane emissions.
豆粕（SBM）和油菜籽粕（CM）是用于泌乳奶牛日粮的蛋白质补充剂，最近有报道称CM具有降低肠道甲烷排放的作用（即较低的Y值）。在推荐将CM作为温室气体（GHG）减排策略之前，有必要研究其对牛奶生产总温室气体排放的净影响。目的是确定在泌乳奶牛日粮中使用CM而非SBM是否能降低每千克脂肪和蛋白质校正乳（FPCM）的温室气体排放量，以及这种降低是否取决于饲料的产地。对加拿大东部（魁北克）和西部（艾伯塔）的一个模拟奶牛场进行了从摇篮到农场大门的生命周期评估。研究方案考察了蛋白质饲料的来源、饲料生产地点以及CM的甲烷减排效果。使用Holos模型估算动物、粪便、作物生产、进口饲料和能源使用产生的温室气体排放。在不同方案下，东部的温室气体强度（COe/kg FPCM）为0.85 - 1.02，西部为1.07 - 1.11，肠道甲烷占总排放量的34%至40%。与SBM相比，在加拿大西部生产的具有低上游排放因子和低Y值的CM使每千克FPCM的COe降低了3%（西部农场）至6.6%（东部农场）。我们得出结论，在泌乳奶牛日粮中使用CM而非SBM可以成为一种温室气体减排策略，这取决于其产地以及是否能降低肠道甲烷排放。
