Quiz 13: Genetic Change Through Selection
Breeding industry has developed specialized breeding farms to distribute improved genetics. The special breeding farms are called elite seed stock producers. These farms focus on producing breeding animals as their main objective of business. By using the genetic information of a species and special breeding programs and technologies like artificial insemination and embryo transfer, the selectively desired sires and dams are produced. The elite seed stock producers allow the rapid propagation of selective breeds and host the other genetic information and technological innovations. The breeding enterprises are capable of marketing as the suppliers of improved and predictable breed stock. The elite seed stock producers sell the selective breeds to multiplier seed stock producers who produce high volumes of improved sires and dams for use by a common breeder. Both the elite and multiplier seed stock enterprisers generate the revenue by the sale breeding animals, semen and embryos. A commercial breeder can produce breeding females on their own but depend on the seed stock sector for production breeding males. Therefore, the commercial breeders sell the offspring produced by the seed stock sector. The finished animals are used to harvest for processed or egg laying operations, wool or fiber or milk.
Genetic selection of breeds is driven by various forces as follows: The cost of the breed created by the marketing enterpriser allows the breed to be selected for buying. Such breeds have demand for qualities like improved growth rate and high yield etc. The environmental condition associated with breed production and growth favors a specific genotype over the other. Some breeds are selected for the physical characteristics like specific color or aesthetic characteristics. The natural selection promoting the genotypes with higher reproductive and survival rates under specific conditions are always favored.
Breed is a population of animals having selective characteristics that are established through the process of selection and the traits are fixed to be passed from one generation to the other. The breeds are produced to match specific functions in relation with market requirements and environmental constraints of specific climates and regions. The breeds are categorized into groups depending on the region of origin or function. Beef cattle breeds are categorized as British and include breeds like Angus, Hereford and Shorthorn. The European breeds include Charolais, Gelbvieh, Limousin, and Simmental. Zebu breeds include Brahman and its derivatives like Brangus and Braford. Zebu breed is originated in Eastern Asia. Goats categorized for meats include Boer and Spanish breeds, for dairy include breeds like Alpine and Nubian. Goats used for fiber include Angora breeds. The sheep breeds for fine wool include Merino and Rambouillet, meat breeds include Hampshire, Dorset and Suffolk. The dual purpose sheep include Columbia and Targhee. The horse breeds include light horse, draft and ponys. The light horse breeds subdivided into categories like Hunter include breeds like Thoroughbred and Warmbloods. The saddle breed includes Arabian, Morgan and Saddlebred. The stock breeds are Quarter horse, Appaloosa and Paint. The draft breeds include Belgian, Clydesdale and Percheron. The Ponys include Shetland and Welsh breeds. Individuals within the breed have some common characteristics but exhibit potential genetic variation to allow wide range of performance in the host of traits.