Submitted to: World Association for the Advancement of Veterinary Parasitology
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2003
Publication Date: August 20, 2003
Citation: GASBARRE, L.C., SONSTEGARD, T.S., VAN TASSELL, C.P., PADILHA, T. USING HOST GENOMICS TO CONTROL NEMATODE INFECTIONS. World Association for the Advancement of Veterinary Parasitology. pp. 119, 2003.
Transmission of cattle GI nematodes can be reduced by identification and management of the few individuals responsible for most of the eggs seeding pastures. To identify the genes coding for parasite resistance we developed a closed-pedigree Angus population containing 343 parasite-challenged calves derived from 43 sire families. Parasite challenge consisted of a 4-6 month exposure on pastures harboring Ostertagia and Cooperia. Genotypying involved 248 microsatellite markers and 432 animals: the parasite-challenged animals, their parents, and historic sires from the extended pedigree. Phenotypic traits analyzed were mean and peak EPG, the EPG profile, and final serum pepsinogen. GenoProb, a program based on multilocus iterative allelic peeling to calculate probability of allele inheritance for each meiosis in the pedigree, was used to determine inheritance probabilities which were then used to identify quantitative trait loci (QTL) on the bovine chromosomes. Models for analysis included sex of calf, age of dam at calving, age of calf, calving season, and sire. In a sire family model, within-sire regression was calculated based on the probability of inheriting 1of the 2 marker alleles from the sire. QTL were identified on bovine chromosomes, 2, 3, 5, 6, 14, and 15 for EPG, and on chromosomes 3, 11, and 18 for serum pepsinogen. We have also developed a 409 gene microarray to identify immune system-related genes showing different levels of expression in resistant or susceptible animals. These data are being combined with current studies involving validation and fine mapping of the QTL to identify the genetic basis for GI nematode resistance in cattle.