|Van Tassell, Curtis|
|Padilha, Terezinha - EMBRAPA, BELTSVILLE MD|
Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 23, 2002
Publication Date: May 30, 2002
Citation: GASBARRE, L.C., SONSTEGARD, T.S., VAN TASSELL, C.P., PADILHA, T. IDENTIFICATION OF GENOMIC REGIONS AFFECTING RESISTANCE TO GASTROINTESTINAL PARASITES OF CATTLE. AMERICAN ASSOCIATION OF VETERINARY PARASITOLOGISTS PROCEEDINGS. pp. 47, 2002. Technical Abstract: A small percentage of the individuals in a cattle herd are responsible for most of the gastrointestinal nematodes transmission and genetic management of 15-25% of the herd could considerably reduce overall parasite transmission. Using a population of linebred Angus cattle that was divergently selected for resistance to GI parasites, a genome-wide scan was performed to identify quantitative trait loci (QTL) related to resistance to infection. Pedigree analysis reveals that >90% of the tested animals were paternally descended from a Wye Angus bull born in 1944. The complete pedigree included information for 931 animals, and 383 calves from over 70 sires had genotypic data recorded for 196 microsatellite markers. Phenotypic traits analyzed were mean, peak, and final numbers of nematode eggs/gram (EPG) of feces and mean and final serum pepsinogen levels. Marker segregations were determined using Genoprob. The analysis model included sex of calf, age of dam at calving, age of calf at parasite challenge, calving season, sire, and within-sire regression on the probability of inheriting one of the two QTL alleles of the sire. The number of progeny with both marker data and phenotypes ranged from 2 to 14 in each of the 43 sire families. A total of 175 of 37,539 tested effects were significant within family (P<0.001), and 17 marker by trait combinations on seven chromosomes out of 905 tested were significant (P<0.01) in across-family F-tests. In both analyses, adjacent markers were found to be significant.