Sheep Genetics Expanding in the US

Sheep breeders in the U.S. expanding gene pools in their sheep herds.


| September/October 2017



sheep

Darrell Pilkington with the Teeswater ram (nearest camera) that ultimatley failed the final Schmallenberg virus test.

Photo by John Wilkes

Some United States sheep breeders dedicated to breeds from the United Kingdom are concerned about shrinking gene pools. Throughout American history, British settlers introduced breeds such as Lincoln, Leicester Longwool, Shropshire, Suffolk, and Hampshire. More recently, some U.S. sheep breeds have morphed into anatomically larger versions of their British counterparts, arguably leading to a decline in meat and overall carcass quality.

The average weight of a U.S. lamb carcass in 1980 was 55 pounds. In recent years, U.S. breeders have produced lamb carcass weights at 67 pounds on average — an additional 12 pounds over the past 37 years. By contrast, a U.K. lamb carcass weighs just 44 pounds.

And U.S. sheep breeders of U.K. breed-types are in need of fresh genetics. After a six-year embargo, the ban on British ovine semen was lifted in May 2016 by USDA Animal Plant Health Inspection Service (APHIS). The opportunity to import fresh genetics is now possible, though the pathway is challenging for U.K. sheep breeders.

Stringent health protocol, lengthy quarantine requirements, and logistics for compliance are major hurdles for the U.K. sheep industry. Extensive health screening of U.K. donor rams is mandated by APHIS. Donor rams must prove to be scrapie-free at the onset. Scrapie-free donor rams then undergo on-farm quarantine, before semen collection. Tests for brucellosis, bovine tuberculosis (TB), border disease, and Schmallenberg virus are taken two to three times. Rams that pass all tests can be moved to U.K. government licensed semen collection centers for U.S. export. A final Schmallenberg blood test, post semen collection, must also be conducted.

Bovine TB is a problem for U.K. cattle herds, although failure of the bovine TB test carries significant ramifications for sheep breeders. Failure of any ram’s TB test means all sheep on a breeder’s farm must be TB tested, and a 5-mile movement-restriction zone established. Despite almost no recorded instances of bovine TB in the national sheep flock, many breeders are not willing to take this risk.

The U.K. freely exports ovine genetics globally to countries like New Zealand that have TB but require no such test. The New Zealand government follows biosecurity measures closely and adheres to many of the most stringent livestock world health standards.





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