Posted: January 9, 2018

Broadening the genetic diversity of Holsteins.

Nearly all Holsteins alive today can be traced back to two bulls from the 1960s: Pawnee Farm Arlinda Chief--whose other offspring include some 16,000 daughters, 500,000 granddaughters, and more than 2 million great-granddaughters--and Round-Oak Rag Apple Elevation, whose descendants surpass in number even Pawnee's.

The two bulls were bred so frequently because their offspring were exceptional milk producers. But intense breeding with only a few individuals can have an unintended side effect--the loss of genetic diversity. And with that loss can come the spread of damaging mutations that can affect the cows' health and milk-producing capabilities, among other things

Thanks to research by Chad Dechow, associate professor of dairy cattle genetics, and Wansheng Liu, associate professor of animal genomics, calves recently born at Penn State may help to reintroduce valuable genetic variance into Holsteins.

The researchers first set out to find descendants of other Holstein lineages.

As luck would have it, the National Animal Germplasm Program in Fort Collins, Colorado, had recently procured semen from two lost Holstein lineages from the University of Minnesota and ABS Global. The samples were used to fertilize eggs to create a dozen embryos from genetically elite Holstein females owned by one of the nation's largest dairy genetics companies--Select Sires Inc. Dechow and Liu implanted embryos from the first lineage into surrogate heifers at Penn State's dairy farm last summer.

The first group of bouncing baby bovines--three males and three females--was born in April, all healthy and full of spunk. Their growth and health are being tracked by animal science doctoral student Han Longfei to determine how they compare to calves from other lineages. An additional 10 calves from another lost lineage are expected to make their appearance later this year.

"After several years of planning, seeing those first calves was exciting," Dechow says. "We hope that the lost genetic diversity they represent will eventually be reintroduced to the Holstein population."

Liu agrees, adding, "We are very happy to see the calves and bring back these lost lines. These calves will further advance our research in cattle genetics, and with that knowledge we can continue to improve genetic diversity, the health of Holsteins, and milk production."

--Amy Duke