Prediction of Enteric Methane‐Related Traits From Body Weight and Milk Composition Traits, Including Ratios of De Novo, Mixed, and Preformed Fatty Acids in Holstein Cows

The aim of this study was to develop prediction equations for methane‐related traits in Holstein cows using body weight (BW) and milk composition traits, including the proportions of de novo (DEN), mixed (MIX), and preformed (PRF) fatty acids in milk fat. A total of 358 measurements from 92 Holstein cows were used in regression analyses for methane emission (CH 4 , L/day), methane conversion factor (MCF), and the CH 4 :CO 2 ratio. Independent variables included BW, energy‐corrected milk (ECM), milk yield, milk protein percentage (PRO), milk fat percentage, lactose percentage, protein‐to‐fat ratio (PFR), DEN, MIX, and PRF. Four well‐fitted equations were developed for CH 4 and MCF. The best fitted equation was as follows: CH 4 = −78.58 + 0.5632 × BW + 8.273 × ECM + 17.75 × PRO − 181.7 × PFR + 6.151 × DEN − 2.225 × MIX. When BW was excluded from the CH 4 equation, prediction bias was observed across parities and lactation stages. This bias was reduced by developing parity‐specific equations. These equations show moderate accuracy in validation. These findings demonstrate that methane‐related traits can be effectively predicted using routinely collected animal and milk composition data, offering the potential for improved methane monitoring and mitigation strategies in dairy production.