The market for omega-3 rich foods and supplements has been growing rapidly in recent years as a wealth of science has begun to demonstrate the benefits of the long chain omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).
Indeed, it has been long suggested that levels of these fatty acids in the human diet have decreased over the years, while levels of shorter chain omega-6 fatty acids have increased – leading to an imbalance in omega-6 (n-6) and omega-3 fatty (n-3) acids that may lead to declines in health.
Now, researchers from Northwest A&F University and the National Beef Cattle Improvement Centre, both in Yangling (Shaanxi), China, have successfully bred cattle that contain higher levels of these essential omega-3 fatty acids.
The team, led by Gong Cheng, introduced a gene known as fat1 into foetal cells from Luxi Yellow cattle. The gene - which was isolated from a nematode worm - codes for desaturase enzymes that are involved in the conversion of omega-6 to omega-3 fatty acids.
Writing in Biotechnology Letters, the team reveal that introducing the fat1 gene to cattle increased the levels of beneficial oils by over five times.
“Importantly, the fatty acid composition analysis showed that overexpression of mfat1 gene elevated the contents of ALA, EPA and DHA in beef, and decreased the omega-6/omega-3 PUFAs ratio by 82.2 % compared to the transgenic negative calf,” wrote the authors.
"We have provided the first evidence that it is possible to create a new breed of cattle with higher nutritional value in terms of their fatty acid composition," said corresponding author Linsen Zan.
Fishy beef?
The team noted that while other research groups are experimenting with increasing levels of omega-3 oils in farmed fish by creating fishmeal rich in new plant sources of EPA and DHA – and that a similar strategy could be used for cattle to produce feedstock rich in omega-3, the new study shows that elevated levels of omega-3 can be directly produced in beef.
Indeed, Cheng and colleagues noted that similar genes have previously been introduced to pigs, dairy cattle and sheep by international research groups.
Gene introduction
The omega-3 fatty acid desaturase (FAD3), encoded by fat1 gene derived from the nematode worm (C. elegans), converts omega-6 fatty acids to omega-3.
“In the study, a plasmid containing the codon-optimized C. elegans fat1 gene (mfat1) was constructed and used to produce transgenic beef cattle by somatic cell nuclear transfer,” explained the team.
In 14 calves that successfully received the fat1 gene, the team reported that the ratio of n-6 to n-3 fatty acids in the transgenic calves decreased from 5.33: 1 to 0.95: 1 compared with negative controls.
"There is much to learn about the best scientific techniques and the best husbandry required to make beef a rich animal source of omega-3 oils for human nutrition, but we have taken the first step," said Cheng – who added that the researchers believe the results of their study could help ensure in the future that the beef people eat is better for them.
Source: Biotechnology Letters
Published online ahead of print, doi: 10.1007/s10529-015-1827-z
“Production of transgenic beef cattle rich in n-3 PUFAs by somatic cell nuclear transfer”
Authors: Gong Cheng , Changzhen Fu, et al