Genetic diversity within a breed is the presence of a large number of genetic variants for each of its characteristics. All breeds within a species share at least 50% of the total diversity for the species as a whole. The other 50% is unique within the species. This variability is significant because it allows the species to adapt to changes in environments or other pressures by selection for the most successful variants. The opposite of genetic diversity is genetic uniformity. A population that is genetically uniform may be exquisitely suited to a particular environment. Unfortunately, specialization frequently results in an inability to meet the challenges imposed by and change in the environment or in selection goals. A truly uniform population has no reserve of options for change. In today’s large scale agricultural systems, only a relatively few highly specialized breeds are used to supply a majority of the world’s food resources. This places the world’s food supply at risk if anything should happen to these breeds such as disease or irreversible adverse genetic mutation. Excerpt from “Taking Stock”, published by The Livestock Conservancy.
In Europe, half of the breeds in existence at the turn of the last century are now extinct and a high percentage of the remaining breeds are in danger of disappearing over the next 20 years. In North America, over one third of livestock and poultry breeds are rare or in decline. A survey undertaken by FAO, has determined that many breeds of livestock have already become extinct, and that 35 percent of all remaining mammalian breeds and 63 percent of avian breeds, reported on an on-going basis by countries to the FAO are currently at risk of extinction. FAO report 2001 on the State of the World’s Animal Genetic Resources for Food and Agriculture.
In Ireland, exclusive use of one variety of potato, the “Lumper”, lead to the great famine. It was cheap food to feed the masses. Potatoes were propagated vegetatively so for all intensive purposes, the potatoes were clones with little to no genetic variation. When the potato fungus called “the Blight” arrived from the Americas in 1845 to Ireland, the Lumper had no resistance to the disease leading to the nearly complete failure of the potato crop across Ireland. Had the farmers used multiple varieties of potato, the famine may not have occurred. Keep in mind that Andean natives were cultivating three thousand varieties before the Spaniards arrived. Today in the US we cultivate 250 varieties.
According to WWF there are fewer than 2500 Giant Pandas left in the wild. There are currently 80 livestock and poultry breeds with similar or fewer animals in their population (9 cattle breeds, 2 goat breeds, 8 horse breeds, 2 donkey breeds, 7 pig breeds, 11 rabbit breeds, 5 sheep breeds, 19 chicken breeds, 6 duck breeds, 6 goose breeds, 5 turkey varieties). World Wildlife Fund and Livestock Conservancy Conservation Priority List 2009
About 20 percent of farm-animal species are endangered, says FAO. The U.N. Food and Agriculture Organization estimates that one in five species of farm animal are in danger of extinction. Of more than 7,600 species that the FAO has in its farm-animal database, 190 have kicked the bucket in the last 15 years -- about one breed a month. The globalization of livestock production is the "biggest single factor" impacting farm-animal biodiversity, says the FAO, as global agriculture focuses heavily on specialized, super-productive livestock. Indeed, a mere 14 species provide 90 percent of the human food supply from animals. FAO's José Esquinas-Alcázar is stressing the importance of maintaining animal genetic diversity, which he says will "allow future generations to select stocks or develop new breeds to cope with emerging issues, such as climate change, diseases, and changing socioeconomic factors."
The Holstein cow now represents an estimated 91 percent of the nation’s dairy stock. With the advent of reproductive technologies such as artificial insemination, this breed has experienced unprecedented selective breeding for increased milk production for decades. In their effort to “improve” the breed, the dairy industry widely used a small number of animals perceived by to be superior breeding stock. As a result, a vast majority of the Holsteins in America have lost much of their biodiversity and are effectively related to only 20 or less animals. Although milk production is excellent in these animals, they have lost much of their fertility, disease resistance, and vigor in order to compensate for high milk yield. Excerpt from “Farm Animal Genetic Resources” published by the FAO
In the early 1990’s a few Holstein calves were observed to grow poorly and died in the first 6 months of life. They were all found to be homosygous for a mutation in the gene that caused Bovine Leukocyte Adhesion Deficiency. This mutation was found at a high frequency in Holstein populations world-wide. (15% among bulls in the US, 10% in Germany, and 16% in Japan.) By studying the pedigrees of affected and carrier animals the source of the mutation was tracked to a single bull that was widely used in the industry. Note that in 1990 there were approximately 4 million Holteins in the US making the affected population around 600,000 animals. From “The Value of Genome Mapping for the Genetic Conservation of Cattle” by J.L.Williams, published by FAO
In the summer of 2006 thousands of dairy cattle in California died from the heat because they could not withstand the extreme temperatures. From news of the Associated Press.
Sheep and Goats
Today, a majority of Australian sheep farms have anthelmintic resistant parasites. There are entire regions in Australia that do not support the sheep industry because it is no longer profitable due to the lack of productivity caused from parasite loads in the sheep.
Of the 15 breeds of swine raised in this country just 50 years ago, 8 are now extinct and most of the remaining purebred types are in danger of extinction. Today, the pork industry rests on a three-way cross between a few highly selected strains of the Duroc, Hampshire, and Yorkshire breeds which have been chosen for performance under intensive husbandry. The other commercial breeds that remain, including the Berkshire and Poland China, have declined in economic importance, and a handful of critically rare breeds barely cling to survival. Excerpt from “Taking Stock” published by The Livestock Conservancy
On Manhattan Island, New York, the hogs rampaged through grain fields until farmers were forced to build a wall to keep them out. The street running along this wall became Wall Street. Oklahoma State University swine fact sheet
During the War of 1812, a New York pork packer named Uncle Sam Wilson shipped a boatload of several hundred barrels of pork to U.S. troops. Each barrel was stamped "U.S." on the docks, and it was quickly said that the "U.S." stood for "Uncle Sam," whose large shipment seemed to be enough to feed the entire army. This is how "Uncle Sam" came to represent the U.S. Government. Oklahoma State University swine fact sheet
The turkey is the most genetically eroded of all livestock species. Only several strains of large white turkey are used for over 90% of all turkey production. These birds have such large breasts that they are no longer capable of breeding naturally. Fertility has been decreasing for the variety. Often, the birds get so big that their legs will collapse under the tremendous body weight. Their fast growth and large bodies also make them prone to heart attacks causing mortalities from shipping stress. Farmers become reliant on hatcheries to provide stock. Without artificial insemination performed by humans, this breed would become extinct in just one generation.
60 breeds of chicken that had been raised in the United States prior to World War II were abandoned in favor of just a handful of high performers. Today, five industrial “improved” breeds of chicken supply almost all of the chicken meat and brown eggs sold as food. White eggs now come almost exclusively from a single breed of industrial white leghorns.
Ten large companies produce more than 90 percent of the nation’s poultry using hybridized, fast growing birds. (National Resources Defense Council). NC State University study shows that the fast growth of the hybrids is supported by the development of thin intestinal linings that allow nutrients to be absorbed very quickly by the body. These extra thin intestinal linings make the birds vulnerable to infection and reduce disease resistance. In effect, it becomes necessary to incorporate antibiotics and anthelmintics. The poor immune system leaves them open to bacterial infection and disease like avian influenza. That’s why biosecurity becomes a huge issue in the poultry industry.
A report from the University of Arkansas Division of Agriculture puts the rapid growth rate of today’s chickens into perspective: “If a [human] grew as fast as a chicken, you would weigh 349 pounds at age two.” Sustainable Agriculture · Thirty-nine percent of the U.S. population uses organic products according to The Natural Marketing Institute (NMI) and SPINS.
Farmers markets have enjoyed rapid growth in the United States. Between 1994 and 2000, the number of U.S. farmers markets increased by 63%, from 1,755 to 2,863 according to USDA.