Abstract
Polyunsaturated fatty acids (PUFAs) play a role in a wide variety of physiological processes. They are produced by a series of desaturation and elongation reactions. ΔΔ<math><mi>Δ</mi></math> -6-desaturase is a membrane-bound enzyme that catalyzes the conversion of αα<math><mi>α</mi></math> -linolenic acid (C18:3 nn<math><mi>n</mi></math> -3) and linoleic acid (C18:2 nn<math><mi>n</mi></math> -6) to stearidonic acid (18:4 nn<math><mi>n</mi></math> -3) and γγ<math><mi>γ</mi></math> -linolenic acid (18:3 nn<math><mi>n</mi></math> -6). It is encoded by the FADS2 gene located on bovine chromosome 29. The aim of this study was to identify a single nucleotide polymorphism in the FADS2 gene and to determine possible associations with milk fatty acid composition in two breeds of dairy cattle, i.e., Jersey and Polish Holstein-Friesian. Direct DNA sequencing revealed the presence of an A-to-G substitution in intron 3 of the FADS2 gene (rs209202414). Both populations were genotyped with an appropriate PCR-RFLP assay. The following genotype distributions were observed: for Jerseys, AA ==<math><mo>=</mo></math> 0.24, AG ==<math><mo>=</mo></math> 0.63, and GG ==<math><mo>=</mo></math> 0.13; for Polish Holstein-Friesians, AA ==<math><mo>=</mo></math> 0.17, AG ==<math><mo>=</mo></math> 0.40, and GG ==<math><mo>=</mo></math> 0.43. In Jerseys, statistically significant relationships were found between the FASD2 genotypes and the following milk fatty acids: lauric ( P=0.0486P=0.0486<math><mrow><mi>P</mi> <mo>=</mo> <mn>0.0486</mn></mrow> </math> ), behenic ( P=0.0199P=0.0199<math><mrow><mi>P</mi> <mo>=</mo> <mn>0.0199</mn></mrow> </math> ), lignoceric ( P=0.0209P=0.0209<math><mrow><mi>P</mi> <mo>=</mo> <mn>0.0209</mn></mrow> </math> ), oleic ( P=0.0386P=0.0386<math><mrow><mi>P</mi> <mo>=</mo> <mn>0.0386</mn></mrow> </math> ), eicosatrienoic ( P=0.0113P=0.0113<math><mrow><mi>P</mi> <mo>=</mo> <mn>0.0113</mn></mrow> </math> ), and docosadienoic ( P=0.0181P=0.0181<math><mrow><mi>P</mi> <mo>=</mo> <mn>0.0181</mn></mrow> </math> ). In Polish Holstein-Friesian cows, significant associations were observed for erucic ( P=0.0460P=0.0460<math><mrow><mi>P</mi> <mo>=</mo> <mn>0.0460</mn></mrow> </math> ) and docosahexaenoic ( P=0.0469P=0.0469<math><mrow><mi>P</mi> <mo>=</mo> <mn>0.0469</mn></mrow> </math> ) acids. The study indicated the A-to-G substitution (rs209202414) in the bovine FADS2 gene as a potential genetic marker for fatty acid composition in cattle milk.