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COUNTRY LIFE IN BC • DECEMBER 2019 But research could be a hard sell to producers concerned about GMO implications


For the past several years, gene editing has become a technology offering viable options to benefit many livestock owners. Slight gene


introducing a naturally occurring genetic variant, or allele.


Semen from the genome-edited polled bull was by MARGARET EVANS


modifications – or edits – have removed traits or improved disease resistance.


Last year, I reported on research on gene-edited pigs and it showed that the specific change in their DNA improved their resistance to the often deadly porcine reproductive and respiratory syndrome. Now, scientists at the University of California, Davis have reported on their collaboration with the Minnesota-based company Recombinetics to gene- edit a dairy bull so that it would not pass on horn growth to its offspring. Many dairy breeds naturally grow horns but the


calves are often disbudded at a young age. Disbudding involves the destruction of horn- producing cells before they grow and attach to the skull. Hornless animals are less likely to injure other animals or people and have fewer aggressive behavioural traits. They require less feeding trough space and are less dangerous to handle and transport than horned animals. “Dehorning is an animal welfare issue and is done


to protect other animals or their human handlers,” said Alison Van Eenennaam, Ph.D., UC Davis, Department of Animal Science. “We were interested in pursuing whether we could use genome editing to introduce that characteristic into traditionally horned dairy breeds.”


She said that the technique would offer a pain- free genetic alternative to removing horns by


collected, cryopreserved and used to artificially inseminate ten estrus-synchronized horned Hereford cows. The bull originated from the University of Minnesota’s dairy crossbreeding program and was 62.5% Holstein, 25% Montbelliarde and 12.5% Jersey. Six pregnancies resulted, with one female and five male calves born in September 2017. In the two years since their birth, Van Eenennaam and her team have been studying the offspring and reported in their published findings that none of the bull’s offspring developed horns and that their blood work and their physical examinations found all the calves healthy. All the data was provided to the US Food and


Drug Administration. Their analysis showed that a fragment of bacterial DNA used to deliver the hornless trait to the bull had integrated alongside one of the two hornless genetic variants (or alleles) that were generated by genome-editing in the bull. “In the case of the bull, it segregated in his


offspring so two of them got the normal, naturally- occurring hornless allele with no bacterial template but the other four got a fragment of the bacterial DNA, known as a plasmid,” said Van Eenennaam. “There is now a technique where you don’t need to use the plasmid and so it’s an artefact of an older approach to editing and is something that is quite easily avoidable by looking for templates and not using those animals or not using templates, or at least the plasmid, at all.”


While the plasmid is harmless to the animals, it’s


integration technically shifted the gene-edited bull to being identified as a GMO bull because it contained foreign DNA from the bacterial plasmid. None of the study animals were destined for the


Gene-editing eliminates horns in dairy bulls Research


food chain. Touchy subject Van Eenennaam said that there has been a lot of


interest in the research work among farmers. But at the same time, they are concerned. “They haven’t necessarily been dairy farmers calling us. The dairy farmers have been so beaten up over GMOs that I think they are asking is there any possibility that activists are going to target this. “I think it’s unfortunate because this technology is quite distinct from older genetic engineering approaches where you are using a gene from another species. But here we are doing basically precision breeding to address what I would argue is a welfare concern. The ultimate beneficiary is the cow. I understand their hesitancy because they don’t want to jeopardize their market.” Van Eenennaam is correct that there has been a


history of fearmongering and misinformation and she fully understands any farmer’s concern about a new genetically based management technique that might come under criticism and, thus, jeopardize the product. But at the same time no one wants any unintended consequences in the breeding process and the application of the gene editing revolution. Proceeding forward will be done with great


caution. The scientists agree that further work must be done if genome editing is to be seamlessly integrated into livestock genetic improvement programs. Alongside that, appropriate regulation will be of extreme importance should gene editing have a role in commercial livestock production. The US FDA recognizes any intentionally altered genomic DNA of animals as new animal drugs requiring oversight. The research paper was published in the journal Nature Biotechnology.


An effective health and safety plan involves everyone.


The planning decisions you make today can affect the health and safety of workers tomorrow.


Find resources to prevent injuries at worksafebc.com/agriculture


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