Farm-level records cut the estimated carbon footprint of Bangladeshi milk by 27%

The 37% fall in the footprint over the study period is close to what higher yield produces on its own. The farm's cows averaged 3.53 kilograms of milk a day in 2018 and 5.76 in 2023, a 63% rise the researchers attribute to genetic selection and improved management, including a balanced diet and more efficient feed management ^[7]. Divide unchanged per-animal emissions by 1.63 times as much milk and the per-kilogram number falls about 39% ^[2]. The measured drop was 37%, so emissions per animal rose a little as the cows ate more ^[6].

"We saw that increasing productivity is really a crucial thing, and very important to reduce the carbon footprint," Uddin said ^[18]. On what that implies for policy, he said: "In developing countries, increasing efficiency and productivity is key to reducing carbon footprint rather than hitting only emissions mitigation strategies" ^[19].

The four emission categories add to exactly 100%, so every share in the breakdown is a share of on-farm emissions ^[5]. Emissions after the milk left the farm were excluded, because the researchers did not have data on how far it traveled or how it was processed ^[11]. Adding transport and processing to the total would push enteric fermentation below 48% without changing a thing about the cows ^[5].

Allocation moves the number by more than six years of herd improvement did. Bangladeshi farms raise cattle for milk and meat together, and about 50% of a farm's emissions are charged to milk; US operations are usually separate, and the share there is closer to 90% ^[14]. Between those two conventions the emissions assigned to milk differ by a factor of 1.8 ^[6]. "If we use that traditional allocation method of emissions, it overestimates emissions," Uddin said. "But if we use the specific allocation method that is applicable to the production system in Bangladesh, it really gives you a different answer" ^[16][17].

Against US and European farms at roughly 1 kilogram per kilogram of milk, 5.18 is about five times higher ^[12][4]. Yield covers much of that gap: the paper cites 30 to 40 liters a day for American and European cows against four to eight liters in Bangladesh, and the study farm's 2023 average of 5.76 kilograms sits near the bottom of the lower band ^[13]. Uddin also measured emissions per unit of nutrient production, the protein or calories for human consumption, which counts what the herd yields as meat ^[15]. On that basis, he reports, the Bangladeshi farm sits on much more similar ground to US producers ^[15].

Standard life cycle assessment guidelines put the nonlactating herd inside the boundary, and the study followed them ^[8]. "You cannot just avoid them because they don't produce milk," Uddin said ^[10]. The phys.org account of the study does not report how much lower the footprint would come out if those animals were dropped, so the size of that boundary effect is unquantified.

The sample is one farm, and a university research farm at that ^[2]. Uddin's own caution is that footprint varies significantly between farms even within the same region ^[20]. The paper describes 2018 through 2023 as a five-year period; counted inclusively, it covers six calendar years ^[8]. Working back from the 27% reduction, the Tier 1 based estimate this work revises was about 7.1 kilograms per kilogram of milk ^[3].