The delivery of genomic sequences for most livestock species over the past 10–15 years has generated the potential to revolutionize livestock production globally, by providing farmers with the ability to match individual animals to the requirements of rapidly changing climates, production systems and markets. The technology which has had the greatest impact to date is genomic selection [1]. Genomic selection uses information from a large number of genetic markers or single nucleotide polymorphisms (SNPs) in conjunction with measurements (phenotypes) of important traits in livestock and plants to estimate breeding values, without requiring precise knowledge of where specific genes are located in the genome. Since the principles of genomic selection were initially proposed in 2001, genomic selection has been widely adopted in animal and plant breeding programs globally because of its ability to improve selection accuracy, reduce phenotyping and generation intervals and increase genetic gains. It has transformed the livestock and plant industries, as well as delivered human health diagnostic applications, adding billions of dollars and strong social and environmental benefits, particularly across the world's higher income countries.
However, genomic selection also requires improvements to the discovery of causal variations and genomic selection methodologies, greater efforts to overcome limitations associated with lack of essential phenotypes for expensive or difficult-to-measure traits, and the ongoing challenges with implementing genomic selection by smallholder livestock farmers in low–middle income countries. This Special Issue examines some of these issues to identify successes and ongoing limitations that must be overcome to achieve practical applications and social, economic and environmental benefits for all livestock producers in the future.