Modelling QTL effect on BTA06 using random regression test day models
Tomasz Suchocki , Joanna Szyda , Q. Zhang
AbstractIn statistical models, a quantitative trait locus (QTL) effect has been incorporated either as a fixed or as a random term, but, up to now, it has been mainly considered as a time-independent variable. However, for traits recorded repeatedly, it is very interesting to investigate the variation of QTL over time. The major goal of this study was to estimate the position and effect of QTL for milk, fat, protein yields and for somatic cell score based on test day records, while testing whether the effects are constant or variable throughout lactation. The analysed data consisted of 23 paternal half-sib families (716 daughters of 23 sires) of Chinese Holstein-Friesian cattle genotyped at 14 microsatellites located in the area of the casein loci on BTA6. A sequence of three models was used: (i) a lactation model, (ii) a random regression model with a QTL constant in time and (iii) a random regression model with a QTL variable in time. The results showed that, for each production trait, at least one significant QTL exists. For milk and protein yields, the QTL effect was variable in time, while for fat yield, each of the three models resulted in a significant QTL effect. When a QTL is incorporated into a model as a constant over time, its effect is averaged over lactation stages and may, thereby, be difficult or even impossible to be detected. Our results showed that, in such a situation, only a longitudinal model is able to identify loci significantly influencing trait variation. © 2012 Institute of Plant Genetics, Polish Academy of Sciences, Poznan.
|Journal series||Journal of Applied Genetics, ISSN 1234-1983, (A 20 pkt)|
|Publication size in sheets||0.55|
|Keywords in English||Dairy cattle; QTL; Legendre polynomials; Longitudinal data|
|Score|| = 20.0, 22-06-2020, ArticleFromJournal|
= 20.0, 22-06-2020, ArticleFromJournal
|Publication indicators||= 4; = 4; : 2013 = 0.96; : 2013 = 1.902 (2) - 2013=1.74 (5)|
|Citation count*||4 (2020-09-24)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.