Abstract :
[en] The purposes of this study were to estimate the genetic parameters of the energy status indicator (C18:1 cis-9) of Holstein cows in early lactation and its relationship with nitrogen use efficiency (NUE) (predicted NUE and milk urea concentration). After editing, the data included 143,517 records within 5 to 50 days in milk from 52,198 cows, and 3,546 animals in the pedigree with 28,427 SNPs. Two multiple-trait repeatability models were used in this study. In early lactation, the average C18:1 cis-9 was gradually decreasing and was highest in May. The heritabilities of C18:1 cis-9 for primiparous and multiparous cows were 0.12 and 0.09, respectively. The C18:1 cis-9 had positive genetic correlations with predicted NUE (from 0.28 to 0.67), and weak genetic correlations with milk yield, milk urea concentration (from-0.15 to 0.14). This study suggests that breeding for NUE alone may enhance energy troubles in early lactation.
