Feed rations in dairy production and their climate footprint
Markos Managos has studied how feed rations based on raw materials with low climate impact can reduce greenhouse gas emissions from milk production without compromising milk yield.
Dissertation November 28 at 09.15 am
Climate change requires the reduction of greenhouse gas emissions from all sectors of society, including food production. Dairy farming provides nutrient-dense foods but constitutes a major source of emissions within the agricultural sector. The sector has already made progress by improving animal productivity and testing additives that decrease methane, but more solutions are needed.
This thesis investigated how ration formulation using ingredients with a low carbon footprint can reduce total emissions whilst still maintaining production. We investigated the effect of ration formulation on greenhouse gas emissions from high-producing dairy cows by formulating and testing two pelleted concentrate mixes with low-carbon footprint ingredients, compared to a commercial concentrate. One mix was based on domestically sourced ingredients, whereas the other was on available by-products. Both concentrates, when fed in a grass-clover silage diet, reduced the feed-related greenhouse gas emissions without lowering milk yield or increasing the amount of enteric methane produced. We also tested partially replacing the grass-clover-silage in the diet for pregnant dairy heifers with whole-crop wheat silage at 50/50 proportions. Growth rate, feed intake, and enteric methane emissions were comparable between pure grass-clover silage and the whole crop wheat silage mix.
Combining the results of these two feed trials showed that low-carbon footprint concentrate mixes can reduce greenhouse gas emissions at the farm gate. The choice of ingredients, however, can affect the land use in various ways; a by-product-based mix reduced land use, whilst a domestically sourced mix increased it. Similarly, partially replacing silage with wholecrop cereal silage increased emissions but reduced land use. A modelling study of dairy production in Norrland, Sweden, further illustrates these tradeoffs. Depending on future consumer values, the scenarios resulted in different outcomes. Intensive systems achieved lower emissions but increased the reliance on feed inputs, whilst net-zero systems required drastic reductions in animal numbers, thereby affecting milk output. More extensive systems reduced the reliance on external feed, but increased milk’s carbon footprint. In contrast, local food systems balanced regional milk production with lower emissions and relied less on feed inputs.
The findings highlight that there is no single solution for sustainable dairy farming. Feed rations can make a difference, but the outcomes depend on the prioritized goals, such as emissions, land use, self-sufficiency, or total milk output. Sustainability, therefore, needs to be assessed at several system levels, investigated from the individual animal to the whole region, to capture the complexity and guide informed decisions for the future of dairy production.
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