Scientists at the U.S. Meat Animal Research Center in Clay Center, NE, have identified a genetic marker that could assist producers in selecting females for increased uterine capacity and litter size.

Research leader Jeffrey Vallet and colleagues discovered a single nucleotide polymorphism, or SNP, in the erythropoietin receptor gene. The hormone erythropoietin binds to this gene and stimulates red blood cell production.

SNPs are genetic variations that provide information about an animal’s genetic value and are useful in breeding programs. In two unrelated studies, scientists showed this newly discovered SNP was associated with increased litter size.

The SNP creates either a T or a C allele, a form of a gene that controls traits such as hair or eye color in humans. In swine, sows with the T allele have an average litter size that is one or two piglets higher than the average litter size of sows with the C allele.

In the study, the T allele occurred at a low frequency but provided a beneficial genetic difference.

Vallet and geneticist Bradley Freking developed an assay to detect the SNP in individual sows, which could one day provide a fast way to identify sows with improved uterine capacity and litter size.