Breeder

A breeder is a person or organization that propagates living organisms by controlled reproduction, typically to preserve a breed, improve traits, or supply animals, seeds, or plants to others. In animal breeding, breeders focus on traits such as temperament, conformation, fertility, and performance, and may work with dogs, horses, cattle, poultry, or other species. In plant breeding, breeders develop new crop varieties and ornamental plants with improved yield, disease resistance, abiotic stress tolerance, or desirable aesthetics.

Methods range from traditional selective breeding and crossbreeding to modern approaches such as artificial insemination, embryo transfer, in vitro fertilization, and genomic selection. Plant breeders may use mutagenesis, hybridization, backcrossing, and marker-assisted selection. Commercial breeders may operate under registries or breed clubs that maintain pedigrees and health standards, while hobbyists may breed hobby animals or seeds.

Ethical and welfare considerations include ensuring animal health and well-being, maintaining genetic diversity to prevent inbreeding, avoiding overbreeding, and complying with animal welfare and transport regulations. In many jurisdictions, commercial breeding is regulated, and reputable breeders emphasize health testing, early socialization, and transparency about lineage and known hereditary conditions.

In nuclear science, the term breeder can also refer to a breeder reactor, a device that creates more fissile material than it consumes by breeding fertile isotopes into fissile ones.