Animal genetic resources for food and agriculture of animal genetic resources includes diversity at species, breed and within-breed level. Known are currently 8,800 different breeds of birds and mammals within 38 species used for food and agriculture. The main animal species used for food and agriculture production are cattle, sheep, goats, chickens and pigs. In the livestock world, these species are often referred to as "the big five". Some less-utilized species include the dromedary, donkey, bactrian camel, buffalo, guinea pig, horse, rabbit, yak, goose, duck, ostrich,partridge, pheasant, pigeon, and turkey. The history of animal genetic resources begins about 12,000 to 14,000 years ago. The domestication of major
Animal genetic resources for food and agriculture sustainability of a breed and therefore to the potential for successful conservation activities." The Pantaneiro cattle of Brazil are only one example of many at risk of extinction. Despite the importance of animal genetic resources, their diversity has been continually decreasing over time. "Factors as causes of genetic erosion: One of the greatest threats to livestock diversity is pressure from large-scale commercial production systems to maintain only high-output breeds. Recent molecular studies have revealed that the diversity of today's indigenous livestock populations greatly exceeds that found in their commercial counterparts. Climate change and its impact on livestock is being studied.