Cradle-to-farm-gate carbon footprint (CFP) of fat-and-protein-corrected milk (FPCM) across specialized dairy and dual-purpose production systems in El Salvador was studied, and mitigation scenarios based on current management were explored. On-farm (methane, nitrous oxide) and off-farm emissions (purchased feeds, fertilizers, fuels, transport) were estimated using data from farm surveys. Milk CFP averaged (±SE) 1.46 ± 0.35 and 2.61 ± 0.67 kg CO₂e kg-1 FPCM in specialized dairies and dual-purpose herds, respectively. In specialized dairies, most CFP came from methane (55 ± 8.7 %) followed by feed production (37 ± 12.9 %), while in dual-purpose systems feed production was largest (49 ± 13.1 %) ahead of methane (42 ± 12.7 %).
In specialized dairies, increasing milk yield by 1.5 kg cow d-1 lowered CFP by 0.10 kg CO₂e kg-1 FPCM (−6.8 %); combining this with manure composting, a higher forage share (0.43→0.55), and a lower replacement rate (33 %→25 %) yielded an additional 0.18 kg CO₂ reduction; a replacement rate drop (25 %→20 %) had marginal effect. In dual-purpose herds, the same yield gain cut CFP by 0.27 kg CO₂e kg-1 FPCM (−10.3%); adding manure composting, increasing forage proportion (0.62→0.70), and increasing average daily gain reduced CFP by a further 0.15 kg CO₂; shortening days open (−30 d) and age at first calving (−4 months) delivered a modest 0.05 kg CO₂ reduction.
At the national scale, weighting system-specific CFPs by their production shares suggests an average milk CFP of ∼2.44 kg CO₂e kg-1 FPCM, close to the global mean. Priority mitigation levers include raising yields, improving forage quality, and manure composting. Future assessments should incorporate meat co-product allocation for dual-purpose and refinement of local emission factors.
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