Associations between feed efficiency and aspects of lactation curves in primiparous Holstein dairy cattle

ABSTRACT Genetic selection for improved feed efficiency in dairy cattle has received renewed attention over the last decade to address needs of a growing global population. As milk yield is critical component metrics animals, our objective was evaluate associations between primiparous Holstein and parameters mathematical model describing individual lactation curves. The Dijkstra curve fit records from 34 heifers with previously estimated measures efficiency. We found that optimal achieved using daily up 21 d capture rise peak monthly herd improvement remainder accurately characterize persistency. In period before yield, associated faster increase shorter time at expense increased mobilization body reserves; this serves reinforce concept are primarily capital breeders versus income breeders. Feed following lactation, as measured by gross efficiency, return costs, net energy positively higher yield. findings early suggest estimates could be evaluating relative conception, rather than parturition better account stored released reserves breeding.