Short Wave Most U.S. Dairy Cows Come From 2 Bulls. That's Not Good.
Nov 12, 2019
Dan Charles, an NPR science correspondent specializing in food and agriculture, dives into the alarming fact that most U.S. dairy cows are descendants of just two bulls, resulting in genetic homogeneity. He discusses how this lack of diversity risks health and sustainability in dairy farming. Charles also highlights innovative efforts at Penn State University aimed at boosting genetic variation through experiments with older bull semen, which may help reclaim lost traits and improve the overall quality of dairy cows.
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Two Bulls?
- Dan Charles read an article claiming all Holstein cows descend from two bulls.
- He investigated this claim, initially skeptical, and found it to be true.
Artificial Insemination's Impact
- Almost all American dairy cows descend from two bulls via artificial insemination.
- Farmers select bulls based on daughters' milk production, leading to genetic similarity.
Heirloom Bulls
- Chad Decau experimented with semen from older bulls to increase genetic diversity.
- He found that some older genes led to cows with more body fat, a trait previously selected against.