Mitigating enteric methane emissions in lactating cows: Impacts of cooling systems under summer heat stress

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Dikmen S., Özkaraca Y.

ADSA 2026 ANNUAL MEETING, Wisconsin, Amerika Birleşik Devletleri, 21 - 24 Haziran 2026, (Yayınlanmadı)

  • Yayın Türü: Bildiri / Yayınlanmadı
  • Basıldığı Şehir: Wisconsin
  • Basıldığı Ülke: Amerika Birleşik Devletleri
  • Bursa Uludağ Üniversitesi Adresli: Evet

Özet

Enteric methane (CH₄) and carbon dioxide (CO₂) are major greenhouse gases (GHGs) in dairy production, exacerbated by heat stress. This study evaluated the effects of cooling system, parity, stage of lactation, and calving season on CH₄, CO₂, CH₄/CO₂ ratio, and CH₄ per unit of milk (CH₄/milk) in 44 lactating Holstein cows during summer, with an average temperature-humidity index (THI) of 79.8 (moderate-to-severe heat stress). Cows were housed in standard free-stall pens (CONT) or pens equipped with fans and sprinklers (TRT) for heat-stress mitigation. Statistical analyses were performed using SAS 9.4 (TS1M6) to determine the effects of cooling system on methane emissions and associated parameters.  Cooling systems reduced daily CH₄ emissions from 3590 ± 2214 g/day in heat-stressed cows to 2004 ± 2133 g/day and lowered the CH₄/CO₂ ratio by 44% (32.2% vs. 18.0%). Emission intensity (CH₄/milk) decreased from 119.8 ± 75.1 g/L in heat-stressed cows to 79.2 ± 97.9 g/L under cooling. Primiparous cows emitted more CH₄ (3572 ± 2586 g/day) and had higher emission intensity (122.2 ± 89.1 g/L) compared to multiparous cows. Late-lactation cows showed the highest CH₄ intensity (135.2 ± 89.2 g/L), reflecting lower productivity. Season of calving influenced emissions, with winter-calving cows showing higher CH₄ (3323 ± 2401 g/day) than summer-calving cows (1816 ± 1151 g/day). These findings demonstrate that cooling interventions under severe summer heat stress not only enhance cow comfort and productivity but also substantially mitigate enteric CH₄ emissions, supporting both animal welfare and environmental sustainability. Integrating targeted cooling and management strategies can help reduce the carbon footprint of dairy systems under future climate change scenarios.

 

Keywords: Enteric methane emission, cooling system, heat stress, Holstein, dairy sustainability