The carbon footprint of pasture-based buffalo milk production in Colombia

Colombia’s water buffalo dairy market has experienced significant growth in recent years, emerging as the industry’s leading sector in milk quality and favorable prices. Buffaloes are renowned for their early maturity and ability to produce high-quality meat. Two key characteristics stand out when considering animals for dual- purpose systems: excellent milk quality suitable for sale, calf rearing and strong maternal abilities. A yield gap analysis was conducted to assess the potential for greenhouse gas emissions mitigation in Colombian buffalo systems to identify achievable buffalo milk productivity. This study is adapted to the standards for life cycle assessment, focusing specifically on greenhouse gas emissions from the International Organization for  Standardization. Two functional units were used for measurement: tons of CO 2 -equivalents (CO 2e ) per hectare (ha) and kilograms of CO 2e per kilogram of fat-and-protein-corrected milk (FPCM). Greenhouse gas emissions were calculated using the 2019 Refinement to the 2006 IPCC guidelines, with emission factors sourced from databases. Emissions were categorized into those associated with animals, feces, and soils, with the corresponding sequestration or assimilation accounted in soils, forage biomass, trees, shrubs, and milk production. The simulations were conducted for 550 kg live-weight buffaloes, with a dry matter intake of 11 kg per day alongside 2 kg of balanced feed, under two milk production scenarios: 1500 liters and 3000 liters per lactation. Herd gross energy (GE) intake was calculated using IPCC Tier 2 equations, considering daily gross energy intake per animal category, diet digestibility, and daily net energy requirements for pregnancy, lactation, growth, activity and maintenance. Dry matter intake (DMI) was determined by dividing gross energy intake values by 18.45 MJ of metabolizable energy per kg dry matter, representing the feed’s energy density. These greenhouse gas emissions encompassed methane (CH4) from enteric fermentation and excretions left in paddocks, nitrous oxide (N 2 O) from excretions deposited on pastures and fertilizer application, and carbon dioxide (CO2 ) from lime and urea application, as well as the burning of fossil fuels. The global warming potential indices GWP100 and GWP* were employed to calculate the impact of emissions. Milk carbon footprints (CFs) ranged from 0.7 to 1.41 kgCO2 -eq kg FPCM-1, but when calculated with the GWP* index, they decreased by nearly 35% for both scenarios.