Methane production in cattle selected for residual feed intake

Methane produced by microbes within the digestive tract of ruminants constitutes a significant greenhouse gas emission and a substantial loss of fermented dietary energy from the host animal. Selection of cattle for improved residual feed intake (RFI) reduces feed intake and can be expected to result in reduced production of enteric methane. This study was conducted to test the relationship between RFI and methane production in bulls consuming a feedlot finishing diet. Lower estimated breeding values for RFI were associated with lower feed intake by bulls and there was a weak positive association between feed intake and enteric methane production rate (MPR; P = 0.05). However no relationship between MPR and RFI was apparent when data were analysed using regression analysis, or when the MPR of bulls with the highest (n = 15) and lowest (n = 15) RFIs were compared. It is concluded that although cattle with superior RFI can be expected to have a lower MPR because of a reduction in feed intake, more accurate ways of measuring MPR, and preferably simultaneous measurement of RFI and MPR, are required to accurately define the correlation between RFI and MPR.