Climate-Resilient Dairy Farming: Genomic Tools and Low-Emission Strategies in a Warming World

Climate change poses an unprecedented dual challenge to the global dairy industry: it exposes cattle to increasingly severe heat stress whilst simultaneously demanding that the sector substantially reduce its own greenhouse gas (GHG) emissions. Dairy cattle, particularly high-yielding Holstein populations selectively bred for temperate environments, are highly susceptible to rising ambient temperatures and humidity, which impair milk production, reproductive efficiency, and animal welfare. Concurrently, livestock supply chains account for approximately 12% of total anthropogenic GHG emissions globally, according to the most recent FAO assessment, with enteric methane from ruminant fermentation representing the single largest source within the sector. This review synthesises emerging evidence on two converging frontiers of innovation: genomic strategies for breeding climate-resilient cattle, and nutritional and microbial approaches for reducing enteric methane emissions. On the genomic front, whole-genome selection approaches using millions of single nucleotide polymorphism (SNP) markers are now enabling the simultaneous improvement of heat-tolerance traits alongside production performance, with Australia at the vanguard of deploying estimated breeding values (GEBVs) for heat tolerance. Genome-wide association studies (GWAS) have identified key candidate genes—including heat shock protein (HSP) family members and the prolactin receptor gene (PRLR)—underlying thermotolerance, whilst CRISPR/Cas9 gene-editing technology has opened the possibility of introducing naturally occurring thermotolerant mutations into susceptible breeds. On the emissions front, the methane inhibitor 3-nitrooxypropanol (3-NOP) consistently reduces enteric methane output by 28–32% in lactating dairy cows without compromising milk yield. Complementary approaches include macroalgae supplementation, dietary fat and nitrate inclusion, and early-life rumen microbiome programming. Integrating these biological, nutritional, and genomic strategies within supportive policy frameworks represents the most viable pathway towards a dairy industry that is simultaneously productive, climate-resilient, and low-emission.