Two Holstein Bulls Supply Most Paternal Genetics

Iola Kansas Dairy Cows Grazing 2013 ( Wyatt Bechtel )

The U.S. dairy industry genetics can be traced to two Holstein bulls from the 1950s and 1960s. Now, researchers at Pennsylvania State University wonder, what did we leave behind?

According to an article published by NPR, PennState researchers are using heirloom semen stored by the USDA to breed modern dairy cows.  They are stepping away from the two primary bulls, Round Oak Rag Apple Elevation and Pawnee Farm Arlinda Chief, to more deeply study the Holstein family tree.

“We’ve lost genetic variation,” said Chad Dechow, a PennState geneticist, to NPR. “Now, some of that variation was garbage that we didn’t want to begin with. But some of it was valuable stuff.”

So far, two of the three cows are producing as much milk as the industry average, according to the article, all while carrying more body condition than their modern peers.

“We’ve kind of selected for tall, thin cows, and that’s a really bad combination,” Dechow said of modern dairy genetics. “They’re infertile, unhealthy. So we need to get away from that.”

In the future, Dechow hopes some of the lost genes may be valuable for the U.S. dairy industry. For example, genes equipping cows for warmer temperatures may be helpful for climate change.

However, he also notes while the paternal genes are derived from two bulls, modern dairy cows have many different mothers and grandmothers. It has largely come down to milk production in the past.

“They keep selecting the same families over and over again,” Dechow said.

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