Genetic heritage

Those of you who have followed this blog since its inception may remember a post which described the sale of our herd of American Milking Devon cattle last September. If we had kept our Devons we would have celebrated the decennial anniversary of having them here on the farm in just two months. The decision to raise Milking Devons, the status of which has been classified as critical by the American Livestock Breeds Conservancy, was motivated by our desire to do our part to preserve rare and heritage breeds of livestock. One unfortunate aspect of commercial livestock farming in the twenty-first century is that the preservation of species diversity is not the focus of many breeding programs. The practice of artificial selection may improve any number of physical and physiological characteristics of both plants and animals. Indeed, selective breeding alone is responsible for the improvement of today’s commercial plant and animal stocks over their not-so-ancient predecessors. Consider Teosinte and its domestication as Maize, for example. Artificial selection requires variation, without it populations cannot be modified. Without variation, natural populations cannot adapt to changing local environments. When this phenomenon occurs in nature we call it natural selection. Because most farmers have become myopically preoccupied by the efficiency of production, most are unaware of or ignore the importance of preserving genetic diversity. The Union of Concerned Scientists has written about this problem. The following points were taken from a piece, found at the website of that group, entitled Industrial Agriculture: Features and Policy.

  • U.S. agriculture rests on a narrow genetic base. At the beginning of the 1990s, only six varieties of corn accounted for 46 percent of the crop, nine varieties of wheat made up half of the wheat crop, and two types of peas made up 96 percent of the pea crop. More than half the world’s potato acreage is now planted to a single variety, the Russet Burbank.
  • Farmers have recognized for decades that the decline in genetic diversity in agriculture is a problem, but it has gotten worse rather than better over that period of time.
  • The pressures on farmers to grow uniform varieties come from many sources, seed companies, food processors, consumers, transporters, and the designers of farm machinery.
  • A decline in the genetic diversity in agriculture is important for a number of reasons. Crops that are very similar to each other in yield and appearance are also similar in their susceptibility to disease. In 1970, the Southern Corn Leaf Blight destroyed 60 percent of the U.S. corn crop in one summer, clearly demonstrating that a genetically uniform crop base is a disaster waiting to happen.
  • In addition, modern crop breeders rely on the broad varieties of crops developed over the centuries as sources of resistance traits. Plants that farmers or gardeners no longer grow are sometimes lost forever, taking with them genes for pest resistance and stress resistance that future farmers may desperately need.

Although these statements focus on plant crops, the very same may apply to animals stocks as well. Although there are more than 100 breeds of cattle in the United States only six typically populate our commercial dairies (Ayrshire, Brown Swiss, Guernsey, Jersey, Holstein, and Milking shorthorn). It is the genes in the bodies of individuals which make up the other 94 breeds which distinguish them from these six. The genes which comprise all 100 breeds form what is called the gene pool. It is this genetic reservoir which banks the species as a whole against disaster in the face of changing environmental circumstance. It is the mission the ALBC, and groups like it, to …  ensure the future of agriculture through the genetic conservation and promotion of endangered breeds of livestock and poultry. You can do your part in supporting plant and animal gene pools by purchasing meat, poultry, and vegetables from those you know to be raising heritage breeds. Small-holding farmers often raise rare breeds because they (the farmers) are less likely to be subject to the commercial pressures mentioned above. It may require more effort on your part to attend a Farmer’s Market (on Saturday morning, perhaps, when you’d prefer to be sleeping in) or to sign on as a member of CSA (Community Supported Agriculture) but if you do, you will know you are doing your part for the long-term survival of all of our important species of food plants and animals.

American Milking Devon heifer calf
Pairodox Grace DOB 10.18.09
(Ox Hill Garnet X Highland Hollow Duke of Devonshire)

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