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Types of Breeds
by Don BixbyThe following article was first published in the American Livestock Breeds Conservancy (ALBC) News, January-February 2003, and reprinted in Rare Breeds NewZ for May 2003. It is presented here with the permission of ALBC and the author, Don Bixby. Our thanks to Don, who is is the ALBC's Technical Program Director. [The illustrations on this page were not part of the original article; those below are included as New Zealand examples of three of the breed types discussed.]
Breeds are groups of animals with a consistent array of genetic variants. Within that large designation are some important major types of breeds. These major types include landraces, standardized breeds, industrial strains, and feral populations. Each of these types reflects differences about the attitude of human caretakers towards the genetic package, and each has something to teach about breeds, genetic packages, and human endeavour.
• Landrace – Landrace, as used here, is a general term that refers to populations of animals that are isolated to a local area where local production goals and situations drive selection, and represent a early stage of breed development.
This landrace designation should not be confused with the specific swine breed, Landrace, or with the Finnish Landrace sheep breed. The landrace concept is important as a general pattern for many important breeds. Most landraces have had long-term selection and production in compromised environments outside of the agricultural mainstream. Isolation, founders, and selection environment all combine to determine the overall type and function of landraces. Isolation for most landraces has been due to geographic factors. As history progresses and development proceeds, the isolation that protected these genetic packages is disappearing. With decreasing isolation, the uniqueness of many landraces is diminishing, and with their disappearance go many highly adapted genetic resources.
• Standardized breeds – Standardized breeds are populations of animals that are enrolled into a herdbook or studbook. They are selected to conform to a standard that describes the ideal physical (or in some cases behavioral) type of the breed. The existence of the standard gives this group of breeds its name. Most standardized breeds descend from landrace populations. Breeders decide what is included and what is excluded in a standardized breed. Eventually, the population is “closed”, that is only offspring of approved parents (generally registered ones) can be registered and recognized as this standardized breed. As the boundary is drawn around a standardized breed, characteristics and traits are intentionally or unintentionally lost. As a result, standardized breeds include less variation than do landraces.
• Industrial strains – Industrial strains are usually not characterized as breeds. In most cases, these are narrowly selected for specific production characteristics in a specific environment that benefits from controlled nutrition, environment, and breeding. The strains are usually given corporate code or brand designations rather than names. Population data has not been available on these strains for the current surveys since they are closely held by the corporations that have developed the strains. Private breeders are typically not involved, and so the documentation of registrations and the like has become superfluous for industrial strains.
• Feral animals – Feral animals are domesticated animals that have returned to a free-living state. It is a peculiar fact of biology that the truly wild type and wild genetic strain are never again truly regained, but some feral animals do indeed approach the wild type. Feral animals are interesting because they have returned to a selection environment where nature rather than humans decide which ones reproduce and which ones do not. Some feral populations are genetically distinct and usually come from a few founders. Others have much broader genetic variation due to constant infusion of new recruits from a wide variety of genetic sources. These few are indeed fascinating for their survival traits.
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