DairyTalk 324: When Heat Stress Exposes Genetic Weakness: Why Extreme Holstein Index Bulls Fail in Arizona - by Helmut Demmelhuber

This podcast episode is based on a technical article examining
the limits of conventional Holstein breeding strategies under
extreme climatic conditions. It analyzes a dairy operation in
Arizona where bulls with very high indexes for milk production
and type perform poorly under heat stress, particularly in terms
of fertility and hoof health. A comparison of winter and summer
data indicates economic losses of up to $360 per cow, largely
driven by declining reproductive performance. In response, the
herd’s breeding strategy has shifted toward sires with positive
daughter pregnancy rates, more moderate type traits, and improved
body condition. For certain cow families, targeted ProCROSS
crossbreeding is also used to increase resilience and
adaptability within the herd. With comments on a "The
Bullvine"-article (March 10th, 2026) vy Andrew Hunt:
https://www.thebullvine.com