Effect of Selection for Milk Production and General Health of the Dairy Cow

Abstract

Pairs of open heifers (43) were purchased as foundation animals to evaluate direct response to selection for milk production and correlated responses of reproduction, digestion, respiration, skin or skeleton and mammary disorders. One heifer of each pair was selected for high genetic potential, and the other was selected for low potential on pedigree evaluations for milk production. High pedigree cows produced more milk, but they also had 9% more digestive disorders, 5% more foot rot, 14% more skin or skeletal disorders, 11% more cases of udder edema, and 2% more lactations affected by mastitis. The foundation animals were assigned randomly to be bred to sires with high or average predicted difference milk. The repeatability of all 14 sires was greater than 70% with an advantage of 610 kg to the 7 high sires when they were chosen. Daughters of high sires produced more milk, had 8% fewer systemic uterine treatments, 3% fewer mammary cuts, more joint or leg injuries, 13% more skin or skeletal disorders, and 19% more cases of udder edema than did daughters of average sires.