Submitted to: Brazilian Animal Science Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 27, 2008
Publication Date: July 24, 2008
Citation: Silva, M.V., Van Tassell, C.P., Sonstegard, T.S., Cobuci, J.A., Gasbarre, L.C. 2008. Estimates of (co) variance components using random regression models for gastrointestinal helminthoid data in Angus cattle. Brazilian Animal Science Society. CD-ROM MEL036. p. 105.
A total of 6,375 FEC measures were determined for 409 animals between 1992 and 2003 from Beltsville Agricultural Research Center Wye Angus herd. Original data were transformed using an
extension of the Box-Cox transformation to approach normality and to estimate (co)variance components. The Random Regression Models (RRM) may be used as a new tool for genetic and non-genetic studies of FEC. Phenotypes were analyzed using RRM, by the Restricted Maximum Likelihood method. Within the different orders of Legendre polynomials used, those with more parameters (order 4)
adjusted FEC data best. Results indicated that the Box-Cox transformation has direct influence on the (co)variances and genetic parameters and the lambda value, estimated by ML, is the more accurate.