Genetic Diversity: Examples of Mistakes Learned from Cows
Breeding Goats for Sustainable Farming
Reading Time: 7 minutes
We have been able to improve livestock production due to their wide genetic diversity. Examples of this success in the dairy industry include Holstein cattle that have doubled milk production over the last 40 years. However, looking closely, improvements in productivity have come at a heavy price of increased health issues and nutritional demands. Furthermore, conservationists warn that dwindling genetic diversity threatens the future of farming, as animals become ill-equipped to adapt to changing conditions or new diseases. The United Nations are so concerned that over 100 countries are already signed up to monitoring genealogies and changing breeding objectives.
Loss of Genetic Diversity—Examples of Diminishing Returns
Since domestication, farm animals gradually adapted to local conditions and became hardy beasts, resistant to local diseases and well adapted to the regional climate. It is only within the last 250 years that breeders have favored physical qualities that led to established breeds. Within the last 60 years, the growing technology of cattle genetics has enabled us to concentrate on production traits such as yield and content of protein and butterfat. However, such focus on a few traits in dairy cows has inadvertently brought with it an increase in infertility and production diseases. The consequences are partly genetic, partly due to the stress imposed on a cow’s body by her high yield, and partly because of increased indoor housing. Cows and their farmers now struggle with mastitis, lameness, metabolic and reproductive issues, and diminishing lifetime profits. Consequently breeding indexes now increasingly include health and fertility traits.
Norway Looks to the Future as France Improves Yield
Agricultural researcher, Wendy Mercedes Rauw, studied the effects of genetic selection for yield at the Agricultural University of Norway and concluded that “when a population is genetically driven towards high production, … less resources will be left to respond adequately to other demands like coping with stressors”. As the cow puts all her energy into producing milk, she has less available for maintaining her health and coping with changes or problems in the environment. Indeed, Holstein milkers need high levels of feed and care and minimal stress to produce well and stay healthy. They would not be able to live a pastoral life. Nordic countries were the first to include health and reproduction objectives in their breeding plans.
Looking then at the major chèvre producer, France, I was surprised to see that mastitis resistance has only recently been incorporated into goat breeding indexes. Until now yield, protein and butterfat content and udder conformation have been the only traits documented. The high use of artificial insemination (AI) when breeding goats in large scale commercial production has led to high-yielding Saanen goats and French Alpine goats with similar physical traits. Biologists’ examination of the genealogies of dairy breeds has shown a narrowing of genetic diversity due to the focus on high yield and widespread use of few males.
This has caused alarm in the Food and Agriculture Organization of the United Nations (FAO), which has produced two reports on the State of the World’s Animal Genetic Resources for Food and Agriculture with the co-operation of 129 countries. In 2007, the FAO devised a global plan to halt the erosion of agricultural biodiversity which 109 countries adopted. By 2020 each nation should have a strategy; research and training is continuing worldwide. Goats are one of the five main species for which scientists are examining genetic diversity. Examples include disease resistance in Ugandan goats, the robustness of Moroccan goats, that adapt to varying environmental conditions, and the genome of domestic and wild goats in Iran. The domestic goat (Capra hircus) originated in this region through domestication of the Bezoar wild goat (Capra aegagrus) and researchers hope that local animals will provide a reservoir of wide genetic diversity.
Examples of Why Biodiversity is Important for Goat Farming
Genetic diversity in livestock is a reservoir of traits that enables farmers to improve their stock and allows animals to adapt to changing conditions. “Genetic diversity is a prerequisite for adaptation in the face of future challenges”, says FAO Director General José Graziano da Silva. As changes occur in climate, diseases and the availability of land and resources, goat varieties with alternative genes allow are able to adapt.
Various past practices have led to dwindling genetic diversity. Examples are the selection of similar traits for commercial gain, the spread of popular breeds worldwide, the overuse of AI (few males siring each generation), and inadvertent inbreeding through lack of family records, herd isolation or by closing herds to protect against spread of disease.
Local heritage breeds are a source of genetic variation and are well adapted to regional conditions. Within the area where they have settled they have good disease resistance and are suited to the climate. Sadly, the demands of commerce have lead to abandoning small-scale production from moderate-yielding animals in favor of high-yielding commercial breeds. Even where heritage breeds have been kept, dilution of the gene pool has occurred due to crossbreeding with popular production breeds. Short term, these measures have improved profitability. However, production breeds have often been developed in a foreign environment and fare poorly in the area where the landrace would have thrived. In France, the hardy French Alpine lives well in the mountains of Savoie, but she is poorly equipped for the damp weather of the northern pastures where she suffers from parasites and respiratory diseases. This has lead to Alpines being farmed indoors with consequent management and welfare issues, while the hardy landrace, Chèvre des Fossés, has brushed extinction and only recently been recognized and protected.
France Takes Up the Challenge
France has recognized that 8 of 10 local breeds are at risk, but at least the genetic resource is still there to save. France’s response to the FAO plan is to lead the EU initiative, investigating complex adaptations in wide-ranging environments. They hope to find a rich resource of biodiversity. “We are dealing with a pressing conservation need”, says Pierre Taberlet, project coordinator, “When a few animals are providing sperm to many, then vital genes are lost generation by generation. In a few decades, we might lose most of the highly valuable genetic resources that humanity has gradually selected over the past 10,000 years.”
In addition, France’s agricultural department INRA and breeding authority CAPGENES are implementing a scheme to document the genealogies of all goats used for commercial production and calculate their effective population, common ancestors, and percentage of inbreeding. The aim is to control these figures and freeze the genetic erosion. They also register and provide financial assistance to local heritage breeders.
Taberlet recommends furthermore to protect the wild ancestor and restore the diversity within industrial breeds. He urges schemes to market products from lower yielding breeds with prices to reflect the costs of production. He warns, “If we lose the genetic resources now, they may be gone forever.” Ecologist Stéphane Joost recommends, “Farmers should keep their local, well-adapted breeds”. They may be less productive short term, but they are the wiser choice in the long run.
Genetic Resources in the United States
What can this mean for the United States, whose dairy breeds were imported in the early 1900s? Those dams probably contained more biodiversity than goats in France and Switzerland today but, as modern American goats have been greatly improved for yield, they will have suffered a similar loss in genetic diversity. Examples of original genetic resources lie in Spanish goats and English (Arapawa) goats imported in the 16th and 17th centuries. The origin of San Clemente goats is unknown, but they represent a unique gene pool quite different from that found in dairy. These rare breeds, as well as feral goats, are adapted to their local area and, if the diversity is still maintained in their gene pool, their descendants will be capable of adapting to changing conditions. These breeds are currently at risk, even critically endangered.
The FAO report is encouraging: more heritage breeds are being protected worldwide, but inbreeding and use of non-native breeds is still commonplace and a major cause of genetic erosion. Europe and North America have the highest proportion of at risk breeds.
EU Horizon 2020: Saving animal DNA for future generations
FAO: Genetic diversity of livestock can help feed a hotter, harsher world, Global plan of action for animal genetic resources adopted
Institut de l’Elevage IDELE: Diversité Génétique, des repères pour agir
The Livestock Conservancy
Oltenacu, P.A., Broom, D.M., 2010. The impact of genetic selection for increased milk yield on the welfare of dairy cows. Animal Welfare UFAW 2010, 39–49.
Overney, J. Dwindling genetic diversity of farm animals is a threat to livestock production. Phys.org.
Taberlet, P., Valentini, A., Rezaei, H.R., Naderi, S., Pompanon, F., Negrini, R., Ajmone-Marsan, P., 2008. Are cattle, sheep, and goats endangered species? Molecular Ecology 17, 275–284.
Originally published in the September/October 2017 issue of Dairy Goat Journal and regularly vetted for accuracy.