A Functional Variant in the Stearoyl-CoA Desaturase Gene Promoter Enhances Fatty Acid Desaturation in Pork

Data on 74 dry-cured hams from Duroc × Iberian pigs were used to examine whether the tag polymorphism AY487830:g.2228T>C in the promoter region of the stearoyl-CoA desaturase [SCD] gene affect fat desaturation and monounsaturated fatty acid (MUFA) as previously described in purebred Duroc hams. Samples were taken from sliced trays of dry-cured hams marketed as Jamón Ibérico de cebo, which were randomly purchased from the same supplier in different stores of the same supermarket chain. Genomic DNA was isolated from each sample to genotype for SCD and gender. Also, a sample of two slices was used to determine fat content and fatty acid (FA) composition by gas chromatography. The effect of the genotype (TT and CT) and gender (barrows and gilts) was estimated under a Bayesian setting. Results showed that the SCD polymorphism was associated to fat composition but not to fat content, with TT hams showing increased C18:1n-7, C18:1n-9, C20:1n-9 and MUFA (probability between 0.92-0.98) and decreased C18:2n-6, C20:4n-6 and polyunsaturated FA (PUFA) (probability between 0.91-0.99) as compared to the CT. As a result, the TT hams had more MUFA (0.95%) and a higher MUFA/PUFA ratio (0.43) than the CT. Barrows had more saturated FA (SFA) and less PUFA than gilts. No differences in MUFA content were found between genders. The SCD polymorphism had a greater impact on MUFA than using hams from barrows instead of gilts. It is concluded that the SCD polymorphism is a good tool to increase MUFA and MUFA/PUFA ratio in Duroc crossbred dry-cured hams.

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Variation in the stearoyl-CoA desaturase gene (SCD) and its influence on milk fatty acid composition in late-lactation dairy cattle grazed on pasture

Archives Animal Breeding ◽

10.5194/aab-63-355-2020 ◽

2020 ◽

Vol 63 (2) ◽

pp. 355-366

Author(s):

Yunhai Li ◽

Huitong Zhou ◽

Long Cheng ◽

Jenny Zhao ◽

Jonathan Hickford

Keyword(s):

Fatty Acid ◽

Milk Fat ◽

Desaturase Gene ◽

Nucleotide Substitutions ◽

Single Nucleotide ◽

Gene Markers ◽

Holstein Friesian ◽

Fat Composition ◽

Stearoyl Coa Desaturase ◽

Jersey Cows

Abstract. Gene markers have become useful tools for improving animal genetics and breeding since they improve the accuracy of selection for superior breeding stock. In this study, the stearoyl-CoA desaturase (Δ-9-desaturase) gene (SCD) was investigated in New Zealand pasture-grazed Holstein–Friesian × Jersey cows. Three nucleotide substitutions were identified in exon 5 of the gene (c.702A/G, c.762T/C and c.878C/T), and a single nucleotide substitution was identified in intron 5 (c.880+105A/G). The c.878C/T substitution would, if expressed, result in the amino acid substitution p.A293V. Four nucleotide substitutions (c.*1783A/G, c.*1883C/T, c.*1984G/A and c.*2066T/C/G) were identified in the 3′-untranslated region (3′-UTR), and these resulted in three nucleotide sequence variants (named a, b and c). The sequence that would encode valine (V) at position 293 of SCD was linked to 3′-UTR variant a, and the sequence that would encode alanine (A) was linked to variants b and c. The frequency of the genotypes was as follows: VV (equivalent to aa: 15.1 %), VA (equivalent to ab+ac: 50.0 %) and AA (equivalent to bb+cc+bc: 34.9 %). The cows with the V variant produced less C10:1, C12:1 and C14:1 fatty acid (FA) but more C10:0, C11:0, C14:0, C16:1 and C18:2 FA than the A variant cows (P<0.001). Effects of c.*1783A/G and c.*2066T/C/G on milk fat composition were also found for the AA cows. The presence of c was associated with decreased levels of C16:1 (P<0.001), C17:1 (P=0.001), C18:2 cis-9, trans-13 (P=0.045), C18:2 cis-9, trans-12 (P=0.018) FA and C16:1 FA index (P<0.001). The presence of b was associated with increased levels of C13:0 iso FAs (P<0.001), monounsaturated FA (MUFA; P=0.002) and C12:1 (P<0.001).

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