Mary had a little lamb, but only once a year. However, Cornell Sheep Program researchers have discovered an unusual form of a gene that prompts ewes to breed out of season as well as conceive at younger ages and more frequently.
They conducted a simple genetic test to identify the presence of the unusual form of the gene, the so-called M allele that other researchers had suspected might be correlated with out-of-season fertility, in their test flock and then validated the gene's relationship with aseasonal breeding by observing that trait in the flock.
The finding, published in the August issue of the Journal of Animal Science (Vol. 87, No. 8), may be a boon for the sheep industry worldwide, especially when combined with the Sheep Program's STAR system a method to manage ewes to lamb five times in three years rather than once a year.
"The primary biological limit for sheep production worldwide is the seasonality of breeding, but the market for high-quality lamb is a 52-week thing," said Doug Hogue, professor emeritus of animal science in the College of Agriculture and Life Sciences. His Cornell colleague Mike Thonney and former Cornell postdoctoral researcher Raluca Mateescu, now at Oklahoma State University co-authored the paper with Andrea Lunsford, a graduate student at OSU.
Although the presence of the M allele has been definitively correlated with the ability to breed out of season, the researchers caution that it may only be a marker for the gene actually responsible for the trait.
"Breeding out of season is a complex trait," Mateescu said, "so there are a lot of genes controlling it." Mateescu observed the phenotype the physical expression of the gene in the researchers' flock during a postdoctoral fellowship at Cornell.
"In this case, we're talking about a receptor gene for melatonin," Thonney explained. Melatonin is a naturally produced hormone commonly found in many animals. The change in
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