Genetic evaluation of Iranian first lactation Holstein cows based upon crude and energy-corrected test day milk records

Correlation between breeding value of crude milk (CM) and energy-corrected milk (ECM) was studied based on a total of 774,013 test day records belongs to 88,456 first-parity Holsteins dairy cattle calving during 1997-2009 in 165 herds (from six provinces). Genetic analysis of the traits was carried out by a fixed regression test day model. In the model, effects of herd, calving year, production month, production age, type of cow genotype (grade or pure Holstein), sperm type, polynomial function, as well as additive genetic and permanent environmental random effects of the cows were included. Mean breeding values as the genetic evaluation is undertaken based on two traits were statistically significant (P