In Italy a random regression (RR) test day (TD) model, analogous to the one adopted in Canada for breeding value estimation (Schaeffer et al., 2000), is under study for genetic evaluation of Holstein dairy cows. Italian and Canadian Holstein populations have similar size, and comparable selection objectives and recording systems. Nevertheless, in Italy, specific covariance parameters need to be estimated to be used in a RR TD model that will substitute the lactation model actually in use. The objectives of this study were: 1) the estimation of (co)variance parameters for production traits and somatic cell scores in Italian Holstein to be used in a national RR TD model; and 2) the comparison of TD RR (co)variance estimates from Italian and Canadian Holstein populations. 

A. B Samore, Paul J Boettcher, J. Jamrozik, A. Bagnato, A. F Groen

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 2002. Session 1, , 1.07, 2002
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