Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: 9/26/2006
Publication Date: 10/10/2006
Citation: Gasparin, G., Miyata, M., Coutinho, L.L., Martinez, M.L., Machado, M.A., Silva, M., Campos, A.L., Sonstegard, T.S., Regitano, L. 2006. Detection of a QTL associated with tick resistance on bovine chromosome 7 (BTA7) using a F2 experimental population. Proceedings of 8th World Congress of Genetics Applied in Livestock Production 8(21-15):1-4. Interpretive Summary: The use of microsatellite markers in an interval mapping analysis, using a bovine F2 Holstein x GYR population, has shown to be an appropriate strategy for mapping tick resistance associated QTL. With only 258 animals, it was possible to detect a QTL of statistical significance associated to resistance or susceptibility to the Boophilus microplus tick. This is the first report of QTL for tick indicator traits. In this first case study, one QTL was found at 56cM from the most centromeric marker of the chromosome 7.
Technical Abstract: The Boophilus microplus tick has become one of the most important bovine ectoparasites, responsible for great losses in the economic system of tropical countries. Since the use of accaricides is not efficient to control tick infestations, we decided to explore the great genetic variability for resistance to ticks between Bos taurus and Bos indicus to raise an experimental F2 population and look for QTL associated with this trait. The effects of sex and the year in which the animal was evaluated were assumed as fixed effects, and the age of the animal at evaluation was considered as a co-variable. By the method of multiple interval mapping, a suggestive QTL (P < 0.05) for tick resistance/susceptibility was detected in chromosome 7 (F = 9.88) at 56cM from the most centromeric marker.