{"id":168,"date":"2017-02-18T01:07:22","date_gmt":"2017-02-18T01:07:22","guid":{"rendered":"http:\/\/blogs.oregonstate.edu\/dairy\/?p=168"},"modified":"2017-04-10T19:07:40","modified_gmt":"2017-04-10T19:07:40","slug":"never-dehorn-keep-elite-genetics-win-win","status":"publish","type":"post","link":"https:\/\/blogs.oregonstate.edu\/dairy\/2017\/02\/18\/never-dehorn-keep-elite-genetics-win-win\/","title":{"rendered":"Never have to dehorn again and keep elite genetics? Win-win!"},"content":{"rendered":"
\n \"two\n
Hornless calves (named Buri and Spotigy) produced by gene editing. Photo from Carlson et al. 2016 Nature Biotechnology 34:479-481<\/figcaption>\n <\/figure>\n

We know that hornless cattle are safer for people, their herdmates, and themselves. Unfortunately, the combination of polledness and elite genes for other, more critical traits (like milk yield and productive life) don\u2019t often appear in the same animals. We could spend several decades using polled sires to introgress the POLLED<\/em> allele (allele = version of a gene) into the broader dairy population, but we would sacrifice gains in other traits, because along with the POLLED<\/em> allele, the calves would get other stretches of less desirable DNA. (However, the nice thing about the POLLED<\/em> allele is that it\u2019s dominant, meaning that only one POLLED<\/em> allele is required. At that same location on the other paired chromosome, there can be the horned allele, but we would still have a polled cow.)<\/p>\n

You may have heard of gene editing, particularly with a system called CRISPRs. These CRISPR molecules can be introduced into target cells and are capable of recognizing a particular stretch of DNA and cutting at that location. If pieces of DNA containing the desired sequence for that location (e.g., the POLLED<\/em> sequence) are made available to the cell at the same time, the cell\u2019s DNA repair machinery will use that \u201cnew\u201d DNA to repair the break in the chromosome. Voila! That repaired chromosome now contains the DNA sequence we want at that location, instead of the sequence that was originally there.<\/p>\n

This type of gene editing has been successfully done in cattle embryos. In this case, the researchers used a more primitive version of CRISPRs called TALENs, but they do the same thing. In embryonic cells from horned cattle, the targeted section of DNA on chromosome 1 was replaced with the POLLED<\/em> DNA sequence. In this proof-of-concept experiment, clones were created from these cells. And they grew no horns! The rest of the DNA in these animals remained the same as it was in the original genetic source, only the horned\/polled location was altered. The two bulls produced (pictured above) will be used in breeding experiments to confirm that their offspring will also be polled.<\/p>\n

This precise gene editing technique could be used to introduce polledness into elite dairy sires. In one generation, we could nearly eliminate the need to dehorn\/disbud calves. That\u2019s assuming there are no regulatory setbacks regarding the gene editing technology. (Ah, the potential sticking point.)<\/p>\n

If you\u2019d like some additional explanation accompanied by video of the polled bulls\u2014currently residing at UC Davis\u2014Science Friday has that here<\/a>. The paper can be found here<\/a> on page 479 (Carlson et al. 2016 Nature Biotechnology<\/em> 34:479-481). I\u2019ve glossed over some of the details, so if you\u2019d like any additional explanation, please post a question via the “Leave a reply” link or email me.<\/p>\n","protected":false},"excerpt":{"rendered":"

We know that hornless cattle are safer for people, their herdmates, and themselves. Unfortunately, the combination of polledness and elite genes for other, more critical traits (like milk yield and productive life) don\u2019t often appear in the same animals. We could spend several decades using polled sires to introgress the POLLED allele (allele = version… Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":8137,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[1150207,1139753],"tags":[],"class_list":["post-168","post","type-post","status-publish","format-standard","hentry","category-geneticsgenomics","category-healthwelfare"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/posts\/168","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/users\/8137"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/comments?post=168"}],"version-history":[{"count":8,"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/posts\/168\/revisions"}],"predecessor-version":[{"id":236,"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/posts\/168\/revisions\/236"}],"wp:attachment":[{"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/media?parent=168"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/categories?post=168"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/dairy\/wp-json\/wp\/v2\/tags?post=168"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}