Animal genetic resources for food and agriculture (AnGR), also known as farm animal genetic resources or livestock biodiversity, are genetic resources (i.e., genetic material of actual or potential value) of avian and mammalian species, which are used for food and agriculture purposes. AnGR is a subset of and a specific element of agricultural biodiversity.
AnGR could be embodied in live populations or in conserved genetic materials such as cryoconserved semen or embryos. The diversity 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.FAO. 2015. The Second Report on the State of the World's Animal Genetic Resources for Food and Agriculture. Section A, p 5. Rome 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.
History of animal genetic resources The history of animal genetic resources begins about 12,000 to 14,000 years ago. The domestication of major crop and livestock species in the early Neolithic time period changed human evolution and lifestyles. This ability to control food production led to major demographic, technological, political and military changes. Consecutively, thousands of years of natural and human selection, genetic drift, inbreeding, and crossbreeding have contributed to the diversification of animal genetic resources and increased the variety of environments and production systems that livestock keeping takes place. Relatively few species have been domesticated; out of the world's 148 non-carnivorous species weighing more than 45 kg, only 15 have been successfully domesticated. The proportion of domesticated birds used for food and agriculture is even lower- 10 out of 10,000. The reason these numbers are so low is because it is rare to find species with all of the behavioral and physiological traits necessary for domestication. These traits include lack of aggression towards humans, a strong gregarious instinct, a "follow the leader" dominance hierarchy, a tendency not to panic when disturbed, a diet that can be easily supplied by humans (herbivores), a rapid growth rate, relatively short intervals between births, and large litter size.
Besides their initial domestication, dispersion and migration of these domesticated species has had an equally important impact on shaping the composition of livestock diversity. The process of migration likely varied between regions, but certainly involved the movement of human populations and cultural exchanges between populations. In order to look back and determine where livestock domestication occurred, osteometric information from archaeological sites, and ancient livestock DNA studies are useful tools.
Other factors such as mutations, genetic drift and natural and artificial selection have also played a role in shaping the diversity of livestock populations. As animal populations migrated away from their original sites of domestication, sub-populations were formed through geographic and genetic isolation. Interbreeding within these sub-populations between individuals that thrived in the local prevailing environmental conditions (and were thus better able to reproduce) contributed to the formation of distinct groups of animals, known as breeds. This isolation of sub-populations allowed the simultaneous increase in diversification between these sub-populations and increase in uniformity within them. Human intervention through artificial selection of animals with desirable characteristics further increased the differentiation among and uniformity within breeds. Examples of traits that have been deliberately selected by humans include growth rate, milk or egg production, coat color, meat quality, and age of maturity, among many others. The process of artificial selection has been the main reason for gains in output from commercial breeds, whereas the adaptation of indigenous livestock to diverse and challenging environments (natural selection) has been the main factor for their continued survival and production value. Overall, selection, whether it be natural or artificial, generally results in reduced genetic variation.FAO. 2007. The State of the World's Animal Genetic Resources for Food and Agriculture, edited by B. Rischkowsky & D. Pilling. Rome.
Over the past 250 years the greatest changes in livestock diversity and creation of formal breeds have occurred mainly due to changes that began in England in the late 18th century. These changes have included development of systematic pedigree and performance recording and applying specific breeding objectives. This led to the fixation of breed-specific traits and an increase in productivity. Some breeds were interbred as distinct, isolated populations, while many breeds continued to interact with each other as a result of intentional cross-breeding or unintended introgression. Before the end of the 19th century, several breeds had been absorbed by other populations. In the 19th century, railways and steamships increased the long-distance transportation of livestock. After the Second World War, artificial insemination became common in cattle and pig breeding. As a result of these developments, a limited number of transboundary commercial breeds, such as the Holstein cow and Large White pig, have become very widespread and nowadays increasingly dominate livestock production globally. Thus, understanding the origins and the history of distribution of livestock is central to maintaining their current utilization and long-term conservation as resources.
Benefits and uses of livestock diversity The wide number of livestock breeds and the genetic diversity within them mean that animal genetic resources have a substantial value to society. The different breeds provide a wide range of animal products and services for the benefit of humankind. The diversity of animal genetic resources allows livestock to be raised successfully in a diverse range of different environments and underpins the supply of a range of different products and services: from meat, milk and eggs to fuel, manure and draught power.
Diversity also allows the flexibility to change breeding goals if needed and emphasize alternative traits in response to changes in markets or other conditions. For example, the Holstein Friesian Cow, which is widely used for its whole milk production. Changes in cereal feed availability or demand for low-solid-content milk may decrease the advantage of breeding Holstein cows.
Different breeds produce specific wool, hairs and leather for clothing, carpets and furniture and are often the basis for traditional garments.
Local breeds that were developed by a given community often have a huge cultural significance for that community. Livestock are often a source of wealth and are critical for its maintenance. They appear frequently in art and often play key roles in traditional customs, such as religious ceremonies, sporting events and weddings. Cultural ecosystem services also create significant economic opportunities in fields such as tourism (including, in the context of food and agriculture, farm holidays and visits to areas with historical or scenic farming or forest landscapes) and recreational hunting.
Breeds that have been developed primarily through natural selection have effectively evolved with their environments and usually provide ecosystem services, such as landscape management, vegetation control, and promotion of biodiversity, that are critical for maintaining those landscapes. For example, the Engadine sheep, which were near extinction in the 1980s, today help to preserve centuries-old grassland in the Alps by eating invasive shrubs. Grazing livestock also help sequester carbon by removing plant material and encouraging regrowth and thus the movement of carbon from the air into soil organic matter.
Greater livestock diversity allows humans to be better prepared to meet future challenges, such as climate change. Having access to a range of diverse livestock traits may allow for greater ability to cope with harsh climates and emerging diseases. Animals with unique adaptive abilities, such as resistance or tolerance to diseases and pests, or ability to thrive on poor feed and cope with dry or hot climates can help humans be more resilient to changes in climate. Within breeds, greater genetic diversity allows for continued selection for improving a given trait, such as disease resistance.
Values of animal genetic resources "From a formal economic perspective, AnGR can have various different types of value for conservation. These values can be categorized as follows Direct use value – results from benefits obtained from the utilization of animal genetic resources, such as the production of milk or meat. Indirect use value – results from the provision of support or protection to other activities that produce benefits, such as through the provision of regulating and supporting ecosystem services (e.g. cycling of soil nutrients, seed dispersal, fire control). Option value – results from the potential benefits of having a given resource available for the future; for example, having genetic variability available that can be used to respond to market and environmental changes. Bequest value – results from benefits that might be obtained from the knowledge that others may derive benefits from the animal genetic resource in the future. Existence value – results only from the satisfaction of knowing that a given animal genetic resource exists, even if no other type of value can be derived from it.
Increasing the direct use value will contribute to the economic sustainability of a breed and therefore to the potential for successful conservation activities."
Threats to livestock diversity 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: (Indiscriminante) cross-breeding Introduction/increased use of exotic breeds Lack of/weak AnGR management policies, programmes or institutions Breeds not profitable/competitive or have poor performance Intensification of production or decline of traditional production systems or small farms Disease/disease management Loss/lack of grazing land or other elements of the production environment Inbreeding or other problems in the management of breeding Migration from countryside/uptake of alternative employment Changes to consumer/retailer demand/ habits Mechanization Value of locally adopted breeds not appreciated Unspecified economic/market factors Climate change Globalization, trade liberalization or imports Lack of infrastructure or support for production, processing or marketing Aging farmers or lack of interest among the young generation"
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.