Observed or phenotypic trends in animal performance can be readily quantified from information collected from research or field populations. Phenotypic performance is determined by the collective impact of systematic effects that vary by trait, but may include herd, year, sex, and age; additive genetic effects; and a remainder that is referred to as the lack-of-fit or unexplained residual. It i...

in this research genetic and phenotypic parameters were estimated using linear and threshold models, for reproductive traits, data from 6 large industrial dairy herd of east azerbaijan province collected by agriculture jihad organization during 10 years (2001-2010). best linear unbiased predictions of traits breeding values were estimated using restricted maximum likelihood method by wombat sof...

Calving records from the Animal Breeding Center of Iran collected from January 1990 to December 2007 and comprising 207 106 first calving events of Holsteins from 2 506 herds were analysed using linear sire models to estimate genetic trends for age at first calving (AFC) and milk traits. Genetic trends were obtained by regressing yearly mean estimates of breeding values on year of birth. In gen...

Weaning weight records of 27,774 Angus calves in 13 herds and 14,738 Hereford calves in 11 herds born during 1953 through 1983 in Virginia were analyzed using regression techniques and maximum likelihood (ML) procedures to estimate phenotypic and genetic trends for adjusted weaning weight (AWWT), weaning weight ratio (WWR) and deviations of AWWT from the mean AWWT of the contemporary group (DEV...