Submitted to: Tropical Agriculture (Trinidad)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2001
Publication Date: October 1, 2001
Interpretive Summary: Microsatellite markers form the scaffolding for the construction of the bovine genetic maps and the mapping of genes influencing economically important traits. They have been used to study the divergence, evolution, and domestication of the bovids and genetic differences across and within breeds. Two bloodlines of Romosinuano cattle exist in the U.S.A. today; one from Costa Rica developed by upgrading (COR) and the other, purebred, from Colombia (COL). Because the bloodlines cannot be distinguished by physical appearance, we attempted to find out if genetic markers could be used to: (1) determine the genetic variation between the two bloodlines and (2) whether an individual's bloodline of origin could be determined based on genetic markers. The discernment of bloodline of origin for individual animals has not yet been accomplished in beef cattle. Using 50 public microsatellite markers, we found that allele frequencies among the shared alleles and alleles unique to either the COR or COL bloodline allowed accurate assignment of each animal to its appropriate bloodline. These results are directly applicable to our breeding program providing the genetic evidence that the two Romosinuano bloodlines should be evaluated for differences in reproductive, growth, nutritional, and carcass merit traits. Additionally, these results could be applied to cattle breeders attempting to identify specific sire lines or dam families to apply marker assisted selection in their breeding programs.
Two primary bloodlines of Romosinuano cattle exist (i.e., a Costa Rican [COR] and a Colombian [COL] bloodline) and have been imported for evaluation at the SubTropical Agricultural Research Station (STARS) near Brooksville, Florida. The two bloodlines are phenotypically indistinguishable except for occasional scurs or rare white spotting observed in the COR bloodline. The objectives of this study were to determine: (1) the level of significance of genetic variation between the two bloodlines; and (2) the level of accuracy with which an individual's bloodline of origin could be determined based on genetic markers. The COR bloodline originated through upgrading from Hereford dams at the University of North Carolina from 1948-50's and was imported in 1990-92 as frozen embryos from the Centro Agronomico Tropical de Investigac#on y Esenanza (CATIE), Turrialba, Costa Rica. The COL bloodline was imported in 1996 from mVenezuela as frozen embryos with no evidence of outcrossing from the pedigrees tracing to Colombian origins. Forty-six individuals from each bloodline were identified and screened across 50 microsatellite loci selected by proximity to published carcass merit quantitative trait loci (QTL), usefulness in previously published genetic distance studies, or chromosomal location maximizing genomic coverage. Unique alleles (n=67, COR and n=50, COL) were detected in 46 of the microsatellite systems comprising up to an allele frequency of 0.511 for a single system. Polymorphism information content values (both maximum and average) and average heterozygosities for the 50 systems were (COR) 0.891, 0.752, 0.571 and (COL) 0.918, 0.705, 0.579, respectively, facilitated correct bloodline