RETRACTED: Variability in Enteric Methane Emissions among Dairy Cows during Lactation.

Area of Science:

• Agricultural Science
• Environmental Science
• Animal Science

Background:

• Enteric methane (CH4) emissions from dairy cows contribute to greenhouse gas output.
• Understanding variability in CH4 emissions is crucial for developing mitigation strategies.
• Previous studies have focused less on within- and across-lactation variability in commercial settings.

Purpose of the Study:

• To investigate variability in enteric CH4 emission rate and emissions per unit of milk across lactations in UK dairy cows.
• To assess the impact of factors such as diet, lactation stage, and cow age on CH4 emissions.

Main Methods:

• Collected 105,701 CH4 spot measurements from 2206 cows on 18 UK dairy farms using robotic milking stations.
• Measured CH4 concentrations in breath samples during milking using an infrared CH4 analyzer.
• Utilized a multiple-experiment meta-analysis model to assess influencing factors on CH4 emissions.

Main Results:

• Mean enteric CH4 emissions were 0.38 g/min and 25.6 g/kg milk.
• CH4 emission rate increased in early lactation and was higher in grazing cows.
• Older cows exhibited lower CH4 emissions per minute and per kg of milk.

Conclusions:

• Enteric CH4 emissions in dairy cows change across and within lactations.
• Herd rankings for CH4 emissions remain consistent, supporting the utility of spot measurements for management.
• Findings provide valuable data for targeted CH4 mitigation strategies in dairy farming.