Ruminants present variability in enteric methane (CH₄) emissions over time and due to changes in dietary characteristics; however, limited information exists regarding the re-ranking according to CH₄ emissions of growing steers during the backgrounding and finishing phases, and the effect of using metabolic modulators such as growth-promoting implants, on gas flux. In this experiment, 46 Angus steers were evaluated during the backgrounding and finishing phases. During the finishing phase, 23 steers were implanted, while 23 steers did not receive a growth-promoting implant. Animal growth performance and gas flux were assessed in each phase. Steers were classified according to the CH₄ production, yield, intensity, and residual methane emissions (RME) at the end of each phase. Steers classified as low CH₄ or RME had lower CH₄ production than high emitters during the backgrounding and finishing phases. Also, between 35% and 83% of the steers re-ranked according to the CH₄ and RME classification from backgrounding to the finishing phase. Therefore, CH₄ or RME classification allows the identification of divergent CH₄ production steers. However, CH₄ or RME classification should be conducted in each phase because a large proportion of animals changed the ranking between the backgrounding and finishing phases. Understanding CH₄ emissions classification and re-ranking due to production phases and metabolic modulators will allow the selection of animals that might emit less CH₄, reducing the environmental impact of the beef industry.

Read the full article in the Journal of Animal Science.