Faecal egg count (FEC) is used to identify and quantify gastrointestinal parasite infestations. However, FEC values are not distributed normally, and a small percentage of the herd is responsible for a majority of parasite transmission. Non-normality is a possible source of error when (co)variance components. A total of 6,378 FEC measures were determined for 409 animals between 1992 and 2003 from BARC Wye Angus herd. In this study, original data were transformed using an extension of the Box-Cox transformation to approach normality and to estimate (co)variance components. Transformation of bovine FEC data utilizing the Box-Cox was effective in reducing the coefficients of asymmetry and kurtosis for all the variables studied, which improved estimates of variance components. These results indicate that after transforming data by the Box-Cox procedure the genetic parameters may be more exact.

T. S Sonstegard, M. VGB Silva, L. C Gasbarre, C. P van Tassell

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume , , 15.35, 2006
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