Livestock News

Penn State researchers diversify Holsteins

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Did you know that nearly all male Holsteins alive today can be traced back to two bulls from the 1960s:  Pawnee Farm Arlinda Chief and Round-Oak Rag Apple Elevation?

“Artificial insemination was really beginning to take off in the 1960s,” said Chad Dechow, a researcher in Penn State’s College of Agricultural Sciences. “Today, three-quarters of Holsteins result from artificial insemination. Even those born from a ‘natural mating’ usually have a grandfather that was an artificial insemination bull. The widespread use of artificial insemination is what allowed these two bulls to have such a large impact.”

There is one additional bull from the 1960s that still appears in the male lineage of a handful of sires — a bull born at Penn State named Penstate Ivanhoe Star. He and Pawnee Farm Arlinda Chief share a common male ancestor born in 1890 called Paul De Kol. While these bulls were responsible for many offspring in the country, they were not the only bulls used for breeding during that era. In fact, thousands of sires from that era have descendants through female lineages. However, over the course of time, the other sires’ lines failed to thrive for several reasons. Penstate Ivanhoe Star is an example.

“He carried two lethal genetic recessives. Once those defects were discovered, many of his male descendants were removed from the population so that the defects would not be propagated so widely,” said Wansheng Liu, a leading authority on bovine Y-chromosome variations at Penn State.

This narrowing of the genetic base is not a good thing for Holsteins because it leads to inbreeding, which has the potential to cause genetic defects, poor health and poor milk production.

Liu and Dechow believed the breed needed a little genetic diversity.

The researchers set out on what they thought would be a difficult task — finding descendants of other lineages that existed in the 1960s. Their first call was to the National Animal Germplasm Program in Fort Collins, Colorado, a repository under the United States Department of Agriculture that collects reproductive samples from agriculturally important species.

The repository recently had 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. Embryos from the first lineage were implanted in surrogate heifers at Penn State’s dairy farm last summer.

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

“After several years of planning, seeing those first calves was exciting,” Dechow said. “The team really didn’t know what they would look like, and the first calf’s white face with white eyelashes was the first thing that we noticed. Of course, how they look is the least important aspect of the project, and what we really hope is that the lost genetic diversity they represent eventually will be reintroduced to the Holstein population.”

Liu agreed, 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.”

“Many people and companies have provided resources to help resurrect these lineages, so it really has been a broad-based industry effort that we believe will enhance the breed’s diversity and make dairy breeders better stewards of our genetic resources,” Dechow said.

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