Assessing variation in enteric methane emissions in dairy cows

A study, which provides an assessment of phenotypic variation in enteric methane emissions among dairy cows on commercial farms, was published in Animal. This work was done by the School of Biosciences of the University of Nottingham, partner in the METHAGENE network.

Methane (CH₄) emissions by dairy cows vary with feed intake and diet composition. Even when fed on the same diet at the same intake, variation between cows in CH₄ emissions can be substantial. The extent of variation in CH₄ emissions among dairy cows on commercial farms is unknown, but developments in methodology now permit quantification of CH₄ emissions by individual cows under commercial conditions. The aim of this research was to assess variation among cows in emissions of eructed CH₄ during milking on commercial dairy farms. Enteric CH₄ emissions from 1,964 individual cows across 21 farms were measured for at least 7 days/cow using CH₄ analyzers at robotic milking stations. Cows were predominantly of Holstein Friesian breed and remained on the same feeding systems during sampling. Significant effects were found for week of lactation, daily milk yield and farm. The effect of milk yield on CH₄ emissions varied among farms. Considerable variation in CH₄ emissions was observed among cows within farms, even after adjusting for fixed and random effects. This study confirms that enteric CH₄ emissions vary among cows on commercial farms, suggesting that there is considerable scope for selecting individual cows and management systems with reduced emissions.

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