Modelling cow longevity policies: Impacts on GHG emissions of the Swiss agricultural sector

Abstract

Context

The agricultural sector has a high potential to reduce greenhouse gas (GHG) emissions. One promising measure is to promote the longevity of dairy cows, as the resulting reduction in replacement heifers reduces the overall GHG emissions of the dairy sector.

Objective

In this study, we analysed the effects of a voluntary policy programme to promote the longevity of dairy cows in Switzerland. We forecasted the effects on agricultural production (milk and meat) and GHG emissions for the Swiss agricultural sector. This voluntary direct programme was implemented by the Swiss government in 2024.

Methods

We used an interdisciplinary method and a data approach that combined several data sources and models. We implemented herdbook data on changes in milk yield and veterinary costs with an increasing number of lactations in a bio-economic farm optimisation approach. The use of an agent-based modelling framework allows the consideration of heterogeneous farm responses to the voluntary direct payment programme, which incentivises an increase in productive life of dairy cows. The results of the agent-based model were then implemented in the GHG model SAGE. Four policy scenarios were simulated. They considered two levels of direct payments (low and high) for the voluntary longevity programme and two fattening strategies for those calves no longer needed for cow replacement (4- and 10-month calf fattening). The results of the longevity scenarios were compared with a reference scenario without these direct payments.

Results and conclusions

Our results show a policy scenario with a high level of direct payments and a 4-month calf fattening strategy has the highest GHG emission reduction potential in Swiss agriculture

(−1.71 % of total agricultural GHG emissions and 998 CHF/t CO₂ equivalent). However, a lower level of direct payments combined with a 4-month calf fattening strategy is more cost-effective with regard to GHG emission reduction (−1.69 % of total agricultural GHG emissions and 471.5 CHF/t CO₂ equivalent). The other scenarios show lower GHG reduction potential and lower cost effectiveness. We find the voluntary direct payment programme has high wind-fall effects because the payments are not linked to changes in longevity but are distributed as long as the average number of lactations of a cow herd is three or more.

Significance

This study is the first to analyse a voluntary policy programme that incentivises farmers to extend the productive life of their dairy cows. Furthermore, both environmental and economic impacts are estimated with a novel mixed modelling approach.