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The Versatile Goat in the History of Domestication and Disease

A herd of alpine goats eating grass / Photo by 123rf.com

 

The domestication of goats has a long history. They were among the first wild animals that people tamed for food production. A new study has investigated the nature of the very first goat domestications in the cradle of civilization by analyzing ancient goat genomes. Goats and humans are susceptible to a skin disease called Contagious Ecthyma and a new report has investigated the virus that became involved in a series of outbreaks in goats of Argentina.

 

Goats: versatile produce animals

 

 

Goats are closely related to sheep and both are placed within the subfamily Caprinae.  Typically, they live between 15 and 18 years. They are one of the oldest domesticated species and there are over 300 breeds providing milk, meat, cashmere/pashmina, and fertilizer. They may also be employed in weed control, as what has been done in China where goats are sometimes released into the tea terraces. The tea leaves have a bitter taste which is not to the goat’s liking; instead, they consume the weeds. Goats are also kept as pets.

Most goats have two horns of different sizes and shapes, depending on the breed. In rare cases, goats can have more than two horns, with up to eight having been noted. Horned domestic goats are the norm because breeding hornless goats often results in sterile offspring. In 2011, according to the Food and Agriculture Organisation of the United Nations, there were more than 924 million live goats around the world, with 60 percent in Asia, 35 percent in Africa and Latin America, and 5 percent in the rest of the world.

 

 

Approximately 2 percent of the worldwide milk supply is contributed by goats, however, domestic goat ownership means that an estimated 65 percent of people in the world drink goat milk. According to FAO, in 2017, the top goat milk producing countries in order of production were India (5 million tonnes), Bangladesh, Sudan, Pakistan, Mali, France, Spain, Turkey, Somalia, and Greece (340 thousand tonnes).

The meat of goat kid is said to be similar to that of spring lamb. Older goats may have flavors of veal or venison. The meat has a low-fat content. Goat milk can be processed into fromage de chèvre (cheese), butter, ice cream, yogurt, cajeta (caramel sauce), and other products. Award-winning soft goat cheese topped with green ants is anticipated to arrive in New York from Australia shortly, pending final Food and Drug Administration approval.

People have a long history of consuming products from domesticated goats. It is thought that goats were amongst the first animals in the world to be domesticated after pigs. Domestication 8,500 years BCE occurred in the cradle of civilization, the fertile crescent stretching from Egypt, to Palestine, to Israel, to Jordan, to Cyprus, to Lebanon, to Syria, the fringes of Turkey, to Iraq, and the fringes of Iran.

 

The first goat domestications

An international study led by Professor of Population Genetics Daniel G. Bradley of Trinity College, Dublin has pieced together a more detailed view of the first goat domestications from the genomes of over 80 goats that lived 8,500 BCE in the fertile crescent. The DNA was extracted from ancient bones. They published their observations in the journal Science. The researchers described the domestication as a mosaic, meaning that there was no single dominant event but many simultaneous, independent ones. This may be reflected in the great variety of goat breeds today. One interesting finding was that very early on, the goats were under selection pressure for coat pigmentation, suggesting that the domesticators valued goat hides, perhaps for garment production.

 

Contagious Ecthyma in goats, sheep, and people

Goat domestication is not without risk. Goats, sheep, and humans are susceptible to a disease called Contagious Ecthyma which is caused by the Orf virus, a Parapoxvirus. It results in pustular dermatitis that normally resolves after a few weeks in humans. It usually only affects people in direct contact with infected animals such as farmers, vets, and slaughterhouse personnel. The lesions are painful and if they occur on the lips or inside the mouth, these could lead to starvation. It is primarily of concern due to the economic losses it causes to farmers. In South America, there were recently described CE outbreaks in Argentina, Brazil, and Uruguay.

Guido A. König of the Instituto de Biotecnología, Centro Nacional de Investigaciones Agropecuarias, Buenos Aires, Argentina, and colleagues recently carried out an investigation to identify and molecularly characterize the ORFV that caused five CE outbreaks in goats in three geographic regions of Argentina during the years 2014-15. They published their study in the journal Frontiers in Veterinary Science.

The lesions occurred on the lips and udders, and feet. From the results of phylogenetic analysis, the researchers concluded that the viruses could have originated from sheep. They recommended careful monitoring of traded animals to ensure new virus will not be introduced into disease-free areas.

 

A sheep with orf virus on its mouth / Photo by Wikimedia Commons

 

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