DairyTalk 233: Healthy Cows, Lost Pregnancies: The Risk of Holstein Haplotypes - by Helmut Demmelhuber

This article explains the significance of Holstein haplotypes HH1
through HH6 and why they represent one of the most critical
hidden risks in modern dairy breeding. Although carrier animals
appear perfectly healthy and often perform at a high level,
mating two carriers of the same haplotype results in early
embryonic loss or miscarriage—typically unnoticed, yet costly in
terms of fertility and profitability. The text emphasizes that
effective haplotype management does not mean culling valuable
genetics, but applying precise mating strategies. When genomic
data is used correctly, breeders can protect reproductive
efficiency while maintaining genetic progress.