Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 2005
Publication Date: October 16, 2005
Citation: Benavides, M.V., Echevarria, F.A., Sonstegard, T.S., Van Tassell, C.P., Gasbarre, L.C. 2005. Genetic variability of a box taurus x bos indicus cross population and validation of genomic regions influencing nematode [absract]. Symposium of Genetic Research in Latin America in the Caribbean. p. 18.
The first Brazilian Brangus (5/8 Aberdeen Angus + 3/8 Nelore) herd has been developed and maintained since 1957 at the Embrapa Southern Brazilian Sheep & Cattle Research Centre in Bage, RS - Brazil (31.3oS 54.1oW). The genetic variability of this herd was studied in 230 12-, 18-, and 24-months old offspring, 4 sires and 102 dams, using a panel of 40 microsatellite markers, mainly from 6 bovine chromosomes. The offspring were exposed to natural challenge of gastrointestinal (GI) parasites when the animals grazed on naturally contaminated pastures during the spring and summer. The predominant parasite genera were Haemonchus, Ostertagia, Trichostrongylus and Cooperia spp in the younger animals. The microsatellite markers were chosen based on previous work at USDA, ARS in Beltsville, MD (USA) where researchers were able to identify quantitative trait loci for nematode resistance in an experimental herd. PCR multiplexes were optimised and analysed by fragment analysis using a ABI 3730 sequencer. The number of alleles varied from 4 to 17 and the polymorphic information content (PIC) from 0.476 to 0.863. Statistical analyses were performed on a set of 91 progeny from four sires and results showed that average logEPG [log(EPG+25)] was significantly associated with markers on BTA6. This result confirmed that this region contains a linkage disequilibrium in different bovine populations, suggesting that this chromosomal region is important for cattle nematode resistance and provides a basis for the mechanisms of genetic resistance to these parasites.