Abstract Objectives Omega-3 polyunsaturated fatty acids (n3 PUFAs) are beneficial to human health. However, the n-3 PUFAs contents of the livestock meat that we consume daily are relatively low. Utilization of transgenic technology to increase n-3 PUFAs contents in livestock may solve this problem. Results The omega-3 fatty acid desaturase (FAD3), encoded by fat1 gene derived from Caenorhabditis elegans (C. elegans),convertsomega-6 polyunsaturated fatty acids (n-6 PUFAs) to n-3 PUFAs. 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. Fourteen transgenic calves were obtained, and the ratio of n-6 to n-3 PUFAs in the transgenic calves