RESEARCH
Gene editing for climate change By Gerard Hutching
Scientists are using gene editing to create cattle that can handle climate change.
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ew Zealand scientists have successfully used CRISPR gene editing to create cows with grey patches rather than black, which means they will be better able to cope with heat. The work has been carried out by scientists at AgResearch’s animal containment facility at the Ruakura campus in Waikato. The Crown Research Institute has been granted approvals for the research, according to conditions set by the Environment Protection Authority (EPA). AgResearch senior scientist Dr Goetz Laible says two Holstein Friesian calves with the gene edit were born live but one died at birth, while the second died at four weeks of age from a navel infection. Both deaths were thought to be linked to the fact they were cloned, rather than from the editing process. Now, the team is working on an alternative way of breeding more calves with the edit, which will avoid the use of the cloning process. The technology could come into its own in a warming climate. A 2007 study showed New Zealand dairy cows become heat stressed for nearly 20% of the time they are being milked, halving yields. In 2016, NZ experienced its hottest year on record, while last year recorded the fourth warmest year. Warmer summers are predicted to increase in number and intensity. Laible says a black coat was just one variable related to heat stress. Others included ambient temperature, relative humidity, wind speed, solar radiation and the animal’s genetics and production levels. “Heat stress is a complex phenomenon with higher absorption by a black coat colour being only one aspect. Generation of the edited cattle would for the first time make it possible to determine the
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This calf’s grey patches are a result of CRISPR genome editing.
impact of just lightening the coat colour on heat stress and milk production, which is the ultimate goal of this study,” Laible says. Heat also makes it difficult for cows to become pregnant, so the gene editing technique may help dairy cows to have the calf every year they need to maintain milk production. Peter Hansen at the University of Florida told New Scientist magazine that studies he and his colleagues made had shown that predominantly white cattle regulate body temperature better and maintain milk yield better than predominantly black cattle. He cautions that while AgResearch’s
approach could work, the effect could be small for cows with access to shade. The AgResearch team managed to create the grey coat by making a small change in a gene involved in pigmentation called PMEL. The change to the PMEL gene was made in fetal skin cells from a male Holstein Friesian that were growing in a dish. Laible says they could have used standard breeding techniques and crossed beef cattle with dairy cattle, but the result would have been livestock that were less than ideal for producing either milk or meat. “After seven days in vitro culture single embryos were non-surgically
DAIRY FARMER
November 2020
