Authors : Hamit Mirtaghioglu and Serhat Arslan
Abstract: This study examines the efficiency of test day (TD) evaluations using random regression model (RRM) utilizing part lactation TDs for the genetic evaluation of bulls and cows. The data consisted of 1.250.000 TD records for first lactation milk yield of 150.000 based Holsteins cattle data base by simulation. A single-trait RRM fitting Legendre Polynomials to model the lactation curve was implemented to analyze milk yield. Correlations indicate that Predicted Transmitting Abilities (PTA) based on 2 TD compared with those from 10 TD for heifers could result in substantial re-ranking in heifer evaluations. The correlations between persistency from evaluations based on 6 TDs and 10 TDs was unexpected given the high correlations. Correlations between persistency PTA estimated from 6 TDs and 10 TDs were lower than expected, indicating caution when interpreting persistency PTA from limited TD information.
Hamit Mirtaghioglu and Serhat Arslan , 2004. Genetic Evaluation with Test Day Models Using Part Lactation Yields . Journal of Animal and Veterinary Advances, 3: 684-686.