Location: Animal Disease ResearchTitle: Ovar-DRB1 haplotypes *2001 and *0301 are associated with sheep growth and ewe lifetime prolificacy Author
|Cinar, Mehmet Ulas - Washington State University|
|Herrmann-hoesing, Lynn - Washington State University|
|Taylor, Joshua - Bret|
Submitted to: Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2016
Publication Date: 12/31/2016
Publication URL: http://handle.nal.usda.gov/10113/63285
Citation: Cinar, M., Mousel, M.R., Herrmann-Hoesing, L.M., Taylor, J.B., White, S.N. 2016. Ovar-DRB1 haplotypes *2001 and *0301 are associated with sheep growth and ewe lifetime prolificacy. Gene. 595(2):187-192.
Interpretive Summary: The major histocompatibility complex (MHC) is a cluster of genes known for immunological functions but it also includes some non-immunological genes. An important gene in the MHC region is DRB1 and while DRB1 has been investigated for many infectious disease traits, its relationship to sheep production traits has not been well-studied. For example, to our knowledge no studies have examined DRB1 in connection with ewe lifetime prolificacy traits. Therefore, this study analyzed association between DRB1 and production traits including growth and ewe lifetime prolificacy in U.S. sheep. A specific combination of markers in the DRB1 gene (*0404 and *0141 haplotypes) were associated with growth traits like weaning weight, mature weight, and average daily gain, as well as lifetime total number of lambs born to a ewe. These results suggest there is at least one functional mutation in or near the DRB1 gene that influences growth and prolificacy traits across several U.S. sheep breeds. While there have been other reports of genetic association with growth traits near DRB1, to our knowledge this is the first report of an association with ewe lifetime prolificacy for any gene on ovine chromosome 20. This will spur additional work on mutation discovery, and may lead to improvements in sheep breeding for growth and reproductive performance.
Technical Abstract: Background: The major histocompatibility complex (MHC) is an organized cluster of tightly linked vertebrate genes with immunological and non-immunological functions. While the important MHC gene DRB1 has been examined in regard to many sheep infectious disease traits, only one study, based on microsatellite markers, has previously examined DRB1 and sheep production traits. Furthermore, to our knowledge no studies have examined DRB1 relationship with lifetime ewe prolificacy traits. Therefore, we analyzed association between expressed DRB1 SNP haplotypes and production traits including growth and lifetime prolificacy in 372 Rambouillet, Columbia, and Polypay sheep. Results: The DRB1 *0404 haplotype was associated with increased weaning and mature weights, as well as average daily gain (Šidák P < 0.05). Interestingly, the *0404 haplotype also showed a trend toward association with increased total number of lifetime lambs born (nominal P = 0.0097; Šidák P = 0.084) and number of lambs born alive (nominal P=0.01; Šidák P = 0.084). In contrast, the DRB1 *0141 haplotype was associated with decreased mature weight (Šidák P = 0.01) and showed nominal (P < 0.05) association with decreased growth. Conclusions: Since the *0404 haplotype was present in all three breeds, these results suggest there is at least one functional mutation in the region that influences growth and prolificacy traits that may be broadly present across several breeds. Furthermore, combined use of the similar *0404 and *0141 multi-marker haplotypes that nonetheless have opposing directions of production trait associations will enhance mutation discovery in this region. If undesirable alleles for underlying mutations can be identified, selective pressure against one or a small number of undesirable alleles may improve production with limited impact on MHC genetic diversity and infectious disease susceptibility.