Is early life programming a methane mitigation solution for Australia’s dairy industry? A literature review

Early life programming has been recognised as a potential enteric methane mitigation strategy. The premise is that the rumen microbiome of the young ruminant is malleable, thereby allowing for intervention to tailor the rumen environment to produce animals with life-long low methane emissions. This review explores the potential to affect the developing ruminal microbiome at different life stages. Exposure to external factors during the pre- and post-weaning stages have been shown to influence ruminal microbial populations with varying duration post-birth, with careful management required to sustain microbial changes for low enteric methane emissions. There is growing evidence that indicates the presence of gastrointestinal tract microbes in the neonatal calf. Interventions aimed at manipulating the ruminal microbiome should be considered as early as, or even prior to, conception. However, the sensitivity of the rumen microbiome to changes in the environment and life stage means that it is currently not a viable methane mitigation solution for the Australian dairy industry, where most enterprises are pasture-based systems. We recommend that future research places an emphasis on understanding the longevity of microbiome changes in young ruminants. Such research would provide valuable insights into the efficacy of early life programming as a methane mitigation strategy on Australian dairy farms and potentially provide a platform to stack shorter-term mitigation strategies to maximise abatement over the life of the cow.