Genetic Diversity: Examples of Mistakes Learned from Cows

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We have been able to improve livestock production due to the original herds’ wide genetic diversity. Examples of this success in the dairy industry comes from Holstein cattle. This breed has doubled milk production over the last 40 years. However, improvements in productivity have come at a heavy price of increased health issues and nutritional demands. This is partly because of increased biological needs, but also due to loss of health traits and genetic variation.

Furthermore, conservationists warn that dwindling livestock biodiversity threatens the future of farming. This is because animals are becoming ill-equipped to adapt to changing conditions or new diseases. The United Nations are so concerned that over 100 countries have already signed up to protect biodiversity. They will do this by monitoring genealogies and changing breeding objectives.

Loss of Genetic Diversity—Examples of Diminishing Returns

Since domestication, farm animals gradually adapted to local conditions. They became hardy, 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, focus on a few traits in dairy cows has resulted in an inadvertent 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 due to the production environment. 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. She 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 a cow puts all her energy into producing milk, she has less available to maintain her health and cope with change. Indeed, Holstein milkers need high levels of feed and care and minimal stress to produce well and stay healthy. Consequently, they would not be able to live a pastoral life. As a result, Nordic countries were the first to include health and reproduction objectives in their breeding plans.

France is a major producer of chèvre goat cheese with extensive commercial breeding programs. I was surprised to see that mastitis resistance has only recently been incorporated into 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) in large scale commercial production has led to high-yielding goats with similar physical traits. Looking at the genealogies of dairy breeds, we find a loss of genetic variation. This is partly due to the focus on high yield and the widespread use of few males.

Worldwide Concern for the Loss of Biodiversity

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.

Meanwhile, 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, robust Moroccan goats that adapt to varying environmental conditions, and the genome of domestic and wild goats in Iran. Researchers hope that local animals will provide a reservoir of wide genetic diversity.

Examples of Why Biodiversity is Important for Goat Farming

Genetic variation in livestock provides a reservoir of traits that enables farmers to improve their stock. Moreover, it 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. Changes inevitably occur in climate, diseases, and the availability of land and resources. In short, adaptable goat varieties, with a range of alternative traits in their gene pool, will be able to cope.

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.

Dangers to Heritage Breeds

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. Nevertheless, the demands of commerce have lead farmers to abandon small-scale production. They swap moderate-yielding animals in favor of high-yielding industrial 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 are often developed in a different environment, and fare poorly in the area where the landrace would have thrived.

In France, the hardy French Alpine lives well in the dry mountains of Savoie. On the other hand, she copes poorly in the damp weather of the northern pastures, where she suffers from parasites and respiratory diseases. This has lead farmers to keep Alpines indoors. However, intensive farming has its own cost and welfare issues. All the while, the hardy landrace Chèvre des Fossés has brushed extinction, and only recently been recognized and protected.

France Takes Up the Genetic Diversity Challenge

France has recognized that 8 of 10 local breeds are at risk. Breeders need to act fast while 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 authorities INRA and CAPGENES are implementing a scheme to document the genealogies of all commercial goats. They aim to calculate the effective population, common ancestors, and percentage of inbreeding. The goal is to control these figures and freeze the genetic erosion. They also register and provide financial assistance to local heritage breeders.

Taberlet suggests we protect the wild ancestor and restore the diversity within industrial breeds. In addition, 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”. Although less productive short term, they make a wiser choice in the long run.

Genetic Resources in the United States

What can this mean for the United States, whose dairy goats originated in imported breeds? Like most modern goats improved for yield, they will have suffered a loss in genetic diversity. They have also descended from a small founder population. Consequently, we must take care to vary bloodlines when making breeding plans.

Examples of original and varied genetic resources in America lie in the landrace Spanish goats. These have adapted to the U.S. landscape and climate over 500 years. Other unique resources lie in Arapawa goats and San Clemente Island goats with their distinct gene pool. These rare breeds, as well as feral goats, are well-adapted to their local area. If we maintain diversity 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. However, 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 breeds at risk.

Sources:

• 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.

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Originally published in the September/October 2017 issue of Dairy Goat Journal and regularly vetted for accuracy.