Most U.S. Dairy Cows Are Descended From Just 2 Bulls. That's Not Good

The drive to make more milk has had an unsavory side effect: Cows have become more genetically similar and less fertile. Scientists are trying to recover valuable genetic variation that was lost.
Read more: https://www.npr.org/sections/thesalt/2019/10/17/770696476/most-u-s-dairy-cows-are-descended-from-just-2-bulls-thats-not-good?source=Snapzu