Editing American bison (section)

===Crossbreeding with cattle===
During the population bottleneck, after the great slaughter of American bison during the 19th century, the number of bison remaining alive in North America declined to as low as 541. During that period, a handful of ranchers gathered remnants of the existing herds to save the species from extinction. These ranchers bred some of the bison with cattle in an effort to produce "cattalo" or "[[beefalo]]".<ref name=Halbert2007>{{cite journal |author1=Halbert, N |author2=Gogan, P |author3=Hiebert, R |author4=Derr, J |year=2007 |title=Where the buffalo roam: The role of history and genetics in the conservation of bison on U.S. federal lands |url=http://www.nature.nps.gov/parkscience/index.cfm?ArticleID=149 |journal=Park Science |volume=24 |issue=2 |pages=22–29 |bibcode=2007PaSci..24...22H |access-date=November 4, 2012 |archive-date=March 3, 2013 |archive-url=https://web.archive.org/web/20130303115257/http://nature.nps.gov/parkscience/index.cfm?ArticleID=149 |url-status=dead }}</ref> Accidental crossings were also known to occur. Generally, male domestic bulls were crossed with bison cows, producing offspring of which only the females were fertile. The crossbred animals did not demonstrate any form of [[hybrid vigor]], so the practice was abandoned. The proportion of cattle DNA that has been measured in introgressed individuals and bison herds today is typically quite low, ranging from 0.56 to 1.8%.<ref name=Halbert2007/><ref name=Polziehn>{{cite journal|doi=10.1046/j.1523-1739.1995.09061638.x|author1=Polziehn, R |author2=Strobeck, C |author3=Sheraton, J |author4=Beech, R |s2cid=85575841 |year=1995|title=Bovine mtDNA Discovered in North American Bison Populations|journal= Conservation Biology|volume=9|issue=6|pages=1638–1643 (1642)|bibcode=1995ConBi...9.1638P }}</ref> Many claimed "beefalo", even those regarded as pedigree, have no detectable bison ancestry.<ref name=":0">{{Cite journal |last1=Shapiro |first1=Beth |last2=Oppenheimer |first2=Jonas |display-authors=1 |date=2024 |title=Most Beefalo cattle have no detectable bison genetic ancestry |url=https://elifesciences.org/reviewed-preprints/102750v1 |journal=eLife |volume=13 |doi=10.7554/elife.102750.1.sa3 |doi-access=free}}</ref> In the [[United States]], many ranchers are now using DNA testing to cull the residual cattle genetics from their bison herds. The U.S. National Bison Association has adopted a code of ethics which prohibits its members from deliberately crossbreeding bison with any other species.<ref>{{cite web |title=FAQ |url=https://bisoncentral.com/faq/ |access-date=March 18, 2022 |website=National Bison Association |language=en-US}}</ref>