Long-chain n-3 fatty acids can lower the risk of lifestyle-related diseases, therefore, we introduced a plant fatty acid desaturation3 (FAD3) gene into mammalian cells. The FAD3 cDNA was isolated from the immature seeds of scarlet flax and optimized to human high-frequency codon usage for enhancement of its expression levels in mammalian cells (hFAD3). We introduced the gene into bovine muscle satellite cells, which can be differentiated into multilocular adipocytes in vitro. After hFAD3 transfection, the cells were differentiated into adipocytes and their fatty acid composition was analyzed by gas chromatography. The level of alpha-linolenic acid (18:3n-3) in transfected adipocytes increased about ten-fold compared with non-transfected adipocytes. In addition, the levels of docosapentaenoic acid (DPA, 22:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) in transfected adipocytes were significantly higher than those in non-transfected adipocytes. Moreover, we produced bovine cloned embryos from the hFAD3 cells by somatic cell nuclear transfer. Blastocyst rates of hFAD3 clones were the same as the control clones using the non-transfected cells (21% vs 27%, P > 0.05). hFAD3 transcripts were detected in all of the blastocysts. These results demonstrate the functional expression of a plant hFAD3 in mammalian adipocytes, and normal development of cloned embryos carrying the hFAD3 gene.