Molecular Technologies in Animal Improvement

Molecular marker technologies have reshaped the way genetic variation is measured and exploited in livestock breeding. This review summarizes the main classes of DNA markers used in farm animals—RFLP, AFLP, RAPD, VNTRs, microsatellites (SSRs) and single nucleotide polymorphisms (SNPs)—and compares their strengths, limitations and practical applications in animal improvement programmes. Particular emphasis is given to co‑dominant markers such as microsatellites and SNPs, which enable accurate estimation of genetic diversity, population structure and inbreeding, and facilitate the construction of dense linkage maps and the mapping of quantitative trait loci. We then discuss how information from these markers is integrated into marker‑assisted selection (MAS) and, more recently, genomic selection approaches to accelerate genetic gain for complex traits including growth, milk yield and composition, fertility, disease resistance and carcass quality across cattle, sheep, pigs and poultry. The role of high‑throughput platforms, such as SNP chips and gene expression microarrays, in enabling genome‑wide association studies and more precise prediction of breeding values is also highlighted. Overall, the review illustrates how combining molecular tools with traditional phenotypic selection can improve the efficiency and accuracy of breeding schemes, while at the same time supporting the conservation of valuable genetic resources and the long‑term sustainability of livestock populations.