Over time, thousands of breeds have evolved or been created within each livestock species.  For example, there are several hundred known breeds of cattle.  Each breed has a unique combination of genes which have been exploited across a wide array of environmental conditions worldwide to ultimately provide human consumers with meat, eggs, milk, fiber and a variety of by-products necessary for our survival.  The opportunity to select individuals from a diverse spectrum of genetic material is the basis for the productive breeds of livestock that are utilized in the commercial sector of agriculture today.  Moreover, hybrid vigor or heterosis, which is the increase in performance of a crossbred animal over that of its purebred parents, is only possible if genetic diversity exists. The application of hybrid vigor is considered by many as one of the most important contributions of genetics to scientific agriculture.
As industrial agriculture has progressed, a few select breeds have been identified that maximize production.  This is especially evident in the commercial turkey business, as broad-breasted white turkeys provide the genetic foundation for virtually the entire industry.  Similar reductions in genetic diversity have occurred in the dairy segment.  According to Don Schrider, the Communications Director of the American Livestock Breeds Conservancy (ALBC), the Holstein, the leader in high volume milk production, provides the genetic standard for the dairy industry.  However, over the last 40 years there has been a sharp reduction in the gene pool of the Holstein breed.
When a breed goes extinct, its unique genetic material is lost forever and can’t be used to give new traits to existing breeds.  Reduced genetic diversity can open up the potential for disease problems and vulnerability to pests.  In other words, a certain breed may no longer be suited to a particular environmental condition without considerable intervention from farmers such as antibiotics or shelter.  Consider how poorly a confinement raised sow would fare if it was placed out on pasture to farrow and raise a litter of pigs.  Furthermore, market conditions can change frequently and in the future may reward a production practice that might favor a different line of genetics.  For example, Mr. Schrider commented that some heritage breed of pigs like the Tamworth, Large Black, and Gloucestershire Old Spots are enjoying renewed interest because of their ability to not only perform well in a pasture situation, but also because of the unique flavor of their meat that is sought after by high-end chefs.  He stated that we don’t know what challenges and opportunities might lay ahead for animal agriculture; genes that might be appropriate today might not be tomorrow.
Preserving livestock genetic diversity is important, not only to maintain current uniqueness among breeds, but to protect the livestock that will be raised to feed future generations of the world. Exploring diverse options in gene pools when looking for sires and dams to expand your herd, and promoting hybrid vigor will help keep your livestock vigorous.


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