Heritage breeds are breeds we have inherited from our ancestors and must pass on to future generations.
Many chicken breeds can be traced back for hundreds of years, and countless breeders have put a great deal of careful crossing and skilful selection into creating and maintaining them.
These breeds have valuable characteristics such as resistance to diseases and parasites, resilience to climatic stress, good forage ability, docility or striking appearance. They all are of great potential importance to future livestock production.
However none of the older breeds can match modern hybrids for meat or egg production in modern production systems.
Development in recent years has therefore concentrated on a very small number of commercial breeds and there is currently considerable concern regarding the number of poultry breeds that are either already extinct or at risk of extinction .
The present trends of creating new colours of existing breeds, recreating old breeds, or randomly crossing various breeds in the backyard have the potential to rapidly erode the genetic integrity of old breeds. Another danger is perhaps the growing number of breeders prefering bantams to the original large birds.
Traditionally breed standards have been based on phenotype (the looks of a bird) and tools to analyse the genotype (the genes of a bird) are only slowly becoming available. So genes which do not manifest themselves in appearance (disease resistance, broodiness, egg-laying ability and so on) are easily lost to show traits.
Croad Langshans have been (and are still) used to create some other excellent breeds (Australorp, Orpington, Maran...). So it is very important to keep all of the original genes for future breeding.
Breeders who want to preserve a heritage variety need to select their stock very meticulously and try to keep their lines genetically pure.
This is not an easy task if inbreeding is to be avoided and the line kept vigorous. It is thought that a minimum of 50 females and about 8 males are needed to be able to select and breed from a wide genetic pool and prevent the decline of a line or a breed.
A beautiful variety of old and interesting breeds still survive and need to be looked after carefully. Extinction is forever.
- FAO (Food and Agriculture Organization of the United Nations 
- The state of the world's animal genetic resources 
- Rare breeds trust of Australia