Analyzing the sheep genome for parasite resistance

Oct 18, 2011

Genetic resistance to a parasitic nematode that infects sheep has been discovered by a team of scientists with the U.S. Department of Agriculture (USDA) and the International Livestock Research Institute (ILRI).

The researchers are the first to detect quantitative trait loci (QTL), genetic locations on chromosomes, for resistance to gastrointestinal nematode in a double-backcross population derived from African native . The parasites, common in tropical regions, cause significant economic and production losses in Africa each year. Sheep infected with parasites suffer from diarrhea, anemia, weight loss and sometimes death.

Geneticist Tad Sonstegard at the Agricultural Research Service (ARS) Henry A. Wallace Beltsville Agricultural Research Center in Beltsville, Md., and researchers at ILRI in Kenya hope to identify genes that increase tolerance to parasites and improve production of grazing animals. ARS is USDA's chief intramural scientific research agency, and this research supports USDA's priority of promoting international food security.

In one study, researchers mapped the regions of the genome that control resistance to gastrointestinal nematode parasites in a sheep population bred by ILRI. Hybrid rams were produced by mating a Red Maasai, which is tolerant to gastrointestinal parasites, to a Dorper, a breed that is more susceptible to the parasite. Several of the hybrid ram offspring were then bred to either Red Maasai or Dorper ewes to complete the backcross.

Scientists genotyped 20 percent of the backcross progeny to map QTL that affect parasite-resistance traits. Blood packed-cell volume and fecal egg count-indicators of parasites-were collected for three months from more than 1,060 lambs that grazed on parasite-infected pastures. Scientists selected lambs for genotyping based on parasite indicators. They detected significant QTL for average fecal egg count and packed-cell volume on chromosomes 3, 6, 14, and 22.

Future studies will focus on genotyping the same animals using the OvineSNP50, according to Sonstegard. The OvineSNP50 is a powerful tool that can examine more than 50,000 locations in the genome.

Findings from this research were published online in Animal Genetics in May 2011.

Explore further: Dutch barnacle geese have more active immune system than same species in the North

More information: Read more about this research in the October 2011 issue of Agricultural Research magazine. www.ars.usda.gov/is/AR/archive/oct11/food1011.htm

Provided by United States Department of Agriculture

not rated yet
add to favorites email to friend print save as pdf

Related Stories

DNA test to revolutionise sheep worm control

Jun 23, 2008

CSIRO scientists have moved a step closer to developing a novel DNA test which has the potential to revolutionise management of one of the biggest threats to sheep health in Australia, the barber’s pole ...

From arc to park

Jan 05, 2010

(PhysOrg.com) -- Parasite infections are an important threat in conservation biology, particularly to individuals that have been bred in captivity for release into the wild.

Recommended for you

Study shows starving mantis females attract more males

13 hours ago

A study done by Katherine Barry an evolutionary biologist with Macquarie University in Australia has led to the discovery that a certain species of female mantis attracts more males when starving, then do ...

African swine fever threatens Europe

14 hours ago

African swine fever, or ASF, is a viral disease that kills almost every pig it infects and is likened to Ebola. It gained a foothold in Georgia in 2007, when contaminated pig meat landed from a ship from ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.