Analysis of the genome of Beefalo, a cross between bison and cattle, reveals little or no bison DNA
People will spend $100 to learn about their genetic ancestry. Some pay even more to learn more about their dog’s genes. But how many have questioned the genetic ancestry of their steak?
The ancestry of the Beefalo breed is its main selling point. Thanks to bison DNA, this hybrid breed would be more robust and resistant to disease and would produce meat that is more tender and richer in protein than conventional beef. But an analysis of the first animals of the breed little or no bison DNA was foundreport the researchers on June 10 in eLife.
“We were surprised to find that most of the Beefalo individuals we sequenced had no detectable bison ancestry,” says Beth Shapiro, an evolutionary biologist at the University of California, Santa Cruz.
Shapiro and his colleagues are studying the genomes of species known to produce hybrids, including bison and cattle, and wondering whether the ancestry of Beefalo’s bison had been lost in the 50 years since they first bred. In the first genome-wide analysis of the breed, his team analyzed preserved semen samples from 47 animals, most collected in the 1970s and 1980s and several from the original Beefalo herd.
Thirty-nine of the animals had no bison ancestry. The eight Beefalos with bison DNA contained even less than the breed standard, defined by the American Beefalo Association as three-eighths bison ancestry.
The ABA disputes these results. Association president Dan Stricker says all “full blood” Beefalo on their registry must pass DNA tests at labs at the University of California at Davis and Neogen Genomics in Edmonton, Alberta, which confirm their bison ancestry.
“We are seriously concerned that the samples used in Dr. Shapiro’s study do not accurately represent modern, registered Beefalo that have been selectively bred for bison characteristics over many generations,” Stricker said.
Researchers acknowledge that they have sampled few of today’s Beefalo, choosing instead to focus on the breed’s founding individuals. But study co-author Jonas Oppenheimer, an evolutionary biologist at the Stockholm Center for Paleogenetics, says it’s unlikely that current individuals have more bison ancestry than the founders.
The lack of bison ancestry in these Beefalo suggests that although interbreeding between bison and cattle is possible, it is biologically difficult. Throughout the 1900s, ranchers attempted to establish stable populations of bison-cattle hybrids. All of these efforts failed, including, it seems, Beefalo’s.
Although Beefalo may contain little bison ancestry, most wild bison have some amount of bovine genes. Environmentalists fear this mixed ancestry could compromise bison’s unique behaviors, disease resistance and even legal protections.
But the results of Shapiro and Oppenheimer – and their broader work on cattle-bilon hybrids – suggest that these concerns may be overblown. “Although there has clearly been some gene flow between the two species since cattle were introduced to North America,” says Shapiro, “it has been much less frequent and much less consequential than previously thought.” »
