Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/7/1999
Publication Date: 1/13/2000
Citation: Gasbarre, L.C., Leighton, E.A. 2000. Genetic resistance to gastrointestinal nematodes of cattle [abstract]. Plant and Animal Genome Abstracts.
Technical Abstract: Gastrointestinal nematodes remain a serious constraint on the efficient raising of cattle throughout the world. Although there are several safe and efficacious anthelmintics in widespread use, changing environmental and consumer concerns coupled with the potential for anthelmintic resistance requires that adjuncts to current control procedures be developed. One means to supplement current control programs is to use host genetics to reduce parasite transmission, thus requiring less intensive anthelmintic use. Calves raised under standard husbandry conditions were monitored for parasites burdens. Using 2 different measures of parasite burdens heritibility for parasite resistance was found to be approximately 0.3 - 0.4. In addition, parasite burdens were not normally distributed in the herd, with a small number of calves being unable to successfully mount immunity against the parasites. Bulls with increased risk of producing susceptible (non-responder) calves were identified, and odds ratios for producing these calves were calculated. Based on these findings cattle identical across their major histocompatibility complex were secondarily bred for enhanced or diminished resistance to GI nematodes. Offspring were challenged by natural exposure over a 4 month period to pastures containing important cattle nematode parasites. To collect phenotypic data, calves were extensively monitored both immunologically and parasitologically throughout the test period, and selected calves were killed to accurately assess parasite burdens. Genotyping of the characterized animals is underway, with the goal of identifying genomic regions associated with resistance to infection.