Genetic evaluation for mortality in female calves in Holstein dairy cows
Mortality of calves is not only costly for dairy cattle farmers, but it is also a problem related to animal health and welfare. Thus, the aim of this study was to estimate genetic parameters of mortality in female calves in different age groups until an age of 450 d (nearly first service). Records of female calves born in the years 1998 to 2010 from 56 Holstein dairy herds were used. Five age periods of mortality: d 1 to 30, d31 to 60, d 61 to 180, d181 to 365, d 366 to 450, and the full period d 1 to 450 were considered. After data editing, more than 67707 female calves were investigated. The pedigree consisted of 725 sires and 993 animals, and for the estimation of genetic parameters, linear sire model was applied. Effects accounted for were fixed effects of herd-year- season, number of dam’s parity, calving ease, and twin as well as the random effect sire. Mortality rates were 2.23, 0.83, 2.62, 1.98, 0.70, and 8.3% for the six mentioned periods, respectively. Although heritabilities were low, and ranging from 0.003 to 0.017, but genetic and phenotypic variation seemed to be sufficiently high to genetically improve the mortality trait in female calves until first service.