Domestic sheep are quadrupedal, ruminant mammals typically kept as livestock. They are the most numerous species of sheep, with a population exceeding one billion. Sheep belong to the Artiodactyla order, like all ruminants, which are even-toed ungulates. While "sheep" can refer to other species within the Ovis genus, it generally pertains to domesticated sheep. Common terminology includes "ewe" for an adult female, "ram" or "tup" for an intact male, "wether" for a castrated male, and "lamb" for a young sheep.
1993: FAO Identifies Sheep Breeds
In 1993, the Food and Agriculture Organization of the UN (FAO) identified 863 breeds of sheep.
1995: First Mammals Cloned from Differentiated Cells
Megan and Morag, two ewes, became the first mammals cloned from differentiated cells in 1995 at the Roslin Institute in Edinburgh, Scotland.
1995: FAO Updates Sheep Breed Count
The FAO's count of sheep breeds was updated to 1,314 in 1995.
2001: Study Reveals Sheep Intelligence
A 2001 study published in Nature by Kenneth M. Kendrick and others revealed that sheep are intelligent animals, capable of recognizing individual sheep and human faces for over two years.
2001: FMD Outbreak Threatens Sheep Breeds
During the 2001 Foot and Mouth Disease (FMD) pandemic in the UK, many sheep were culled, putting some rare British breeds at risk of extinction.
2004: US Sheep Losses Statistics
In 2004, the US economy experienced a loss of 600,300 sheep, with predators and diseases being the leading causes.
2004: Predation Impact on Sheep
Predation was a significant threat to sheep in 2004, accounting for over one-third of sheep deaths in the United States. Canids, including domestic dogs, were responsible for most deaths.
2006: FAO's Latest Sheep Breed Count
As of 2006, the FAO had identified 1,229 breeds of sheep.
2008: Sheep Genome Sequencing
While the sheep genome wasn't fully sequenced as of 2008, a detailed genetic map was published, and a draft version was created using information from other mammalian genomes.
2012: Transgenic Sheep "Peng Peng" Cloned
Chinese scientists cloned a transgenic sheep named "Peng Peng" in 2012, splicing his genes with those of a roundworm to enhance the production of healthier fats for human consumption.