Estimating Enteric Methane Quantities through Bulk Tank Milk Analysis
Les Producteurs de lait du Québec launched this project in July 2023 with Lactanet’s assistance. This project is being carried out with financial support from the Quebec government as part of its 2030 Plan for a Green Economy.
Background
Enteric methane emissions account for around half of the greenhouse gas (GHG) emissions in Canadian milk’s carbon footprint. This source of emissions has been deemed a priority in the national commitment to reduce our GHGs and in the entire dairy industry’s desire to provide consumers with “low-carbon” milk.
A variety of practices and strategies exist when it comes to reducing the methane produced in the digestion process. These primarily involve making changes to herd and feed management and monitoring their effectiveness in the field to validate the anticipated reduction targets.
Enteric methane quantities cannot be measured on a daily basis for each animal on a farm. They are always estimated based on models (separate equations for each animal category that specifically link feed and productivity parameters) developed by scientists. While dozens of fairly advanced models exist that are representative of reality, they all have the disadvantage of requiring hard-to-obtain data. For this reason, they can only be used to estimate average annual emissions of enteric methane.
Process
This process is transparent, inclusive and based on a globally recognized reference framework: the UN Sustainable Development Goals (SDGs). To carry out this process, the Chair in Eco-Consulting at the Université du Québec à Chicoutimi analyzed the extent to which sustainable development was incorporated into the organization’s activities and assisted Les Producteurs de lait du Québec in defining its priorities and identifying associated actions.
This analysis not only identified the actions that have already been taken and should be reinforced, but also new actions, in the interest of continuing the organization’s and producers’ efforts. The UN SDG targets were put in order of priority by cross-referencing progress in achieving the relevant targets for the organization with their importance. In doing so, 6 priority targets, 30 medium-term targets and 28 reinforcement targets were identified.
Its main objective is to estimate the quantity of enteric methane produced by all dairy cows in a herd by analyzing their bulk tank milk. Since the milk produced will be collected and sampled every other day, a well-established routine will provide a large quantity of essential data for the project.
The methane emitted will be estimated by analyzing the infrared (IR) reflectance spectrum of milk in its composition, including its fatty acid profile, and by collecting other relevant production variables (see the diagram below).
In the second phase, the model developed will be validated using the bulk tank milk from around fifty other farms (without sensors). Exhaustive herd (inventory, parity, genotype), feed and management data will be collected to verify the model’s sensitivity to various parameters that are believed to influence methane emissions, i.e. reduction strategies.
Farms will be selected from all Quebec farms on the basis of their model-estimated emission intensity (CH4 estimated per kg of milk or per cow) to cover the scale of the model’s response spectrum and select low-, medium- and high-intensity herds. In addition to validating the model’s sensitivity, these farms will be able to implement enteric methane reduction strategies in the final years of the project and their benefits will be tracked almost continuously thanks to this model.
The project will include other activities in pursuit of the following objectives:
- Estimate the enteric methane produced by other animals in the herd (heifers, calves and dry cows) using conventional prediction models to complete the inventory of this GHG source;
- Estimate all other sources of GHG emissions at the sixty or so dairy farms in the study from a life-cycle perspective, using a farm calculator that will be selected after a review of current tools in order to calculate milk’s carbon footprint on these farms;
- Index, better understand and assess the cost-benefit ratio of the enteric methane reduction strategies being used;
- Help improve Lactanet’s genetic index for methane efficiency and encourage interested producers to use this genetic index;
- Develop the IT infrastructure so that the estimated quantities of enteric methane produced by lactating cows that have been obtained from the model, based on the bulk tank milk samples, can be made available.