Genetic correlations between milk production traits and somatic cell scores on test day within and across first and second lactations in Holstein cows

摘要: Abstract The genetic correlations between milk production traits (daily yield, 305-day and lactation persistency as the difference yields at days 240 60) daily somatic cell score (SCS) within across first second lactations in Holstein cows were estimated by using a multiple trait test day (TD) animal model. data set consisted of 200,095 TD SCS records from 21,238 their 143,051 15,281 second. Data analyzed two-trait, two-lactation random regression Genetic additive variance component estimates coefficients. yield both positive peaked early stage. In contrast, negative, except very These suggested that focusing selection on increasing would likely increase SCS, whereas selecting for increased decrease during lactations. results could help to overall without SCS.