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

• Main Authors: Y. Li, H. Zhou, L. Cheng, J. Zhao, J. Hickford
• Format: Article
• Language: English
• Published: Copernicus Publications 2020-11-01
• Series: Archives Animal Breeding
• Online Access: https://aab.copernicus.org/articles/63/355/2020/aab-63-355-2020.pdf

<p>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 (<span class="inline-formula">Δ</span>-9-desaturase) gene (<i>SCD</i>) was investigated in New Zealand pasture-grazed Holstein–Friesian&thinsp;<span class="inline-formula">×</span>&thinsp;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<span class="inline-formula">+</span>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<span class="inline-formula">^′</span>-untranslated region (3<span class="inline-formula">^′</span>-UTR), and these resulted in three nucleotide sequence variants (named <span class="inline-formula"><i>a</i></span>, <span class="inline-formula"><i>b</i></span> and <span class="inline-formula"><i>c</i>)</span>. The sequence that would encode valine (V) at position 293 of <i>SCD</i> was linked to 3<span class="inline-formula">^′</span>-UTR variant <span class="inline-formula"><i>a</i></span>, and the sequence that would encode alanine (A) was linked to variants <span class="inline-formula"><i>b</i></span> and <span class="inline-formula"><i>c</i></span>. The frequency of the genotypes was as follows: <i>VV</i> (equivalent to <i>aa</i>: 15.1&thinsp;%), <i>VA</i> (equivalent to <span class="inline-formula"><i>ab</i>+<i>ac</i></span>: 50.0&thinsp;%) and <i>AA</i> (equivalent to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><mtext mathvariant="italic">bb</mtext><mo>+</mo><mtext mathvariant="italic">cc</mtext><mo>+</mo><mtext mathvariant="italic">bc</mtext></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="61pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="bb73c420fc528c40fcd87a4c53f6a4ae"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-355-2020-ie00001.svg" width="61pt" height="10pt" src="aab-63-355-2020-ie00001.png"/></svg:svg></span></span>: 34.9&thinsp;%). The cows with the <span class="inline-formula"><i>V</i></span> 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 <span class="inline-formula"><i>A</i></span> variant cows (<span class="inline-formula"><i>P</i>&lt;0.001</span>). Effects of c.*1783A/G and c.*2066T/C/G on milk fat composition were also found for the <i>AA</i> cows. The presence of <span class="inline-formula"><i>c</i></span> was associated with decreased levels of C16:1 (<span class="inline-formula"><i>P</i>&lt;0.001</span>), C17:1 (<span class="inline-formula"><i>P</i>=0.001</span>), C18:2 <i>cis</i>-9, <i>trans</i>-13 (<span class="inline-formula"><i>P</i>=0.045</span>), C18:2 <i>cis</i>-9, <i>trans</i>-12 (<span class="inline-formula"><i>P</i>=0.018</span>) FA and C16:1 FA index (<span class="inline-formula"><i>P</i>&lt;0.001</span>). The presence of <span class="inline-formula"><i>b</i></span> was associated with increased levels of C13:0 <i>iso</i> FAs (<span class="inline-formula"><i>P</i>&lt;0.001</span>), monounsaturated FA (MUFA; <span class="inline-formula"><i>P</i>=0.002</span>) and C12:1 (<span class="inline-formula"><i>P</i>&lt;0.001</span>).</p>