Rare breed (agriculture)

In modern agriculture, a rare breed is a breed of poultry or that has a very small breeding population, usually from a few hundred to a few thousand. Because of their small numbers, rare breeds may have a threatened conservation status, and they may be protected under regional laws. Many countries have organizations devoted to the protection and promotion of rare breeds, for which they each have their own definition. In botany and horticulture, the parallel to rare animal breeds are heirloom plants, which are rare cultivars.

There are several definitions of "breed" and "rare breed". Breeds may be defined as a group of animals that share visible characteristics, such as Pinto horses, which are all spotted. A stricter definition insists that breeds are "consistent and predictable genetic entities", which means that individuals from that breed will produce offspring that is predictably similar to their genitors, and that this similarity is genetically based. This biological definition is useful for conservation, which treats breeds as reliable sources of genetic diversity.

Conservation organisations each have their own definition of what constitutes a rare breed. The Rare Breeds Survival Trust (RBST) and the (ALBC) both divide rare breeds into five categories, "critical" being the rarest. The ALBC places a livestock breed under "critical" status when it has "fewer than 200 annual registrations in the United States and estimated global population less than 2,000". The RBST determines the status of a breed by the number of its breeding females in the United Kingdom. For horses and sheep, fewer than 300 is considered "critical", whereas goats and pigs must have fewer than 100 to join that category.

The Poultry Club of Great Britain considers a poultry breed "Rare" when it does not have its own breed club. These "Rare Breeds" are catered by the Rare Poultry Society (RPS). The RPS does not look after breeds that count few individuals but have their own breed club.

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