Most U.S. Dairy Cows Come From 2 Bulls. That's Not Good.

Short Wave

NPR

Daily News, Nature, Life Sciences, Astronomy, Science, News

4.7 • 6K Ratings

🗓️ 12 November 2019

⏱️ 10 minutes

🔗️ Recording | iTunes | RSS

🧾️ Download transcript

Summary

NPR science correspondent Dan Charles explains why most of the dairy cows in America are descended from just two bulls, creating a lack of genetic diversity that can lead to health problems. He also visits a lab at Penn State University where scientists are trying to change that. Follow reporter/host Emily Kwong on Twitter @emilykwong1234. Email the show at [email protected].

Transcript

Click on a timestamp to play from that location

0:00.0	You're listening to Shortwave from NPR.
0:05.6	Emily Quang here, your host, Gwen Maddie Safiah is off for the day.
0:09.4	And I'm here with NPR Science Correspondent, Dan Charles.
0:12.6	Hey, Emily.
0:13.6	Hey, Dan.
0:15.1	So today you've brought us a story about cows.
0:18.7	Right.
0:19.7	It started a few months ago.
0:22.0	I saw an article in an online publication called Undark.
0:26.5	This article asserted that all of the whole steen cows, which is the breed that's most
0:32.4	of the dairy cows in the country, that they were all descended from exactly two bulls.
0:38.1	Two bulls?
0:39.1	And I said to myself, this cannot be true.
0:43.2	So you went off to find out if this was true or not?
0:46.2	And what'd you find?
0:47.8	It is true.
0:48.8	Okay.
0:49.8	There are almost 9 million dairy cows in this country.
0:52.6	And apparently almost all of them are descended from exactly two bulls, which if you want to
0:58.2	get technical about it, means in this entire population of bulls, there are only two
1:03.2	Y chromosomes represented.
1:05.7	That's of all the bulls that produce practically all the dairy cows in this country.
	...

Please login to see the full transcript.

Previous episode | Next episode

Disclaimer: The podcast and artwork embedded on this page are from NPR, and are the property of its owner and not affiliated with or endorsed by Tapesearch.

Generated transcripts are the property of NPR and are distributed freely under the Fair Use doctrine. Transcripts generated by Tapesearch are not guaranteed to be accurate.