title: Influence of oilseed supplement ranging in n-6/n-3 ratio on fatty acid composition and Δ5-, Δ6-desaturase protein expression in steer muscles.
abstract: This study investigated effects of roasted or extruded oilseed supplementation ranging in n-6/n-3 ratios from 0.3 to 5.0 on the fatty acid composition and expression of delta-5 desaturase (Δ5d) and Δ6-desaturase (Δ6d) protein in commercial steer cheek (m. masseter) and diaphragm (pars costalis diaphragmatis) muscles. In general, the n-6/n-3 ratio of the diet had a subsequent effect on the muscle n-6/n-3 ratio (P < 0.05), with muscle 18:2n-6 and 18:3n-3 content relating to proportion of dietary soya bean and linseed (P < 0.01). Compared with canola, pure linseed and soya bean diets reduced 14:1c-9 and 16:1c-9 (P < 0.05) but increased 18:1t-11 and c-9,t-11 conjugated linoleic acid (CLA) content (P < 0.01). Oilseed processing had a minor influence but extruded oilseeds increase 18:1t-11 and c-9,t-11 CLA compared with roasted (P < 0.05). Polar lipid 18:3n-3 and n-3 long-chain polyunsaturated fatty acid (LC, ⩾20 carbons PUFA) derivative content increased in relation to dietary linseed supplementation in the diaphragm (P < 0.01), whereas only 18:3n-3 was increased in the cheek (P < 0.01). Protein expression did not differ between diets; however, in each muscle the Δ5d protein expression had a stronger association with the desaturase products rather than the precursors. The relationship between Δ5d protein expression and the muscle LC n-6/n-3 ratio was negative in both muscles (P < 0.05). The relationship between Δ6d protein expression and the LC n-6/n-3 ratio was positive in the cheek (P < 0.001) and negative in the diaphragm (P < 0.05). In conclusion, diet n-6/n-3 ratio affected muscle 18:2n-6 and 18:3n-3 deposition, whereas the Δ5d and Δ6d protein expression had some influence on the polar lipid LC-PUFA profile. Results reaffirm that processed oilseeds can be used to increase the proportion of fatty acids potentially beneficial for human health, by influencing the formation of LC-PUFA and reducing the n-6/n-3 ratio.
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3. tyler.turner@agr.gc.ca
authors.forename: T D
authors.initials: TD
authors.lastname: Turner
authors.forename: A
authors.initials: A
authors.lastname: Mitchell
authors.forename: J
authors.initials: J
authors.lastname: Duynisveld
authors.forename: J
authors.initials: J
authors.lastname: Pickova
authors.forename: O
authors.initials: O
authors.lastname: Doran
authors.forename: M A
authors.initials: MA
authors.lastname: McNiven
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D015153:Blotting, Western / Q000662:veterinary; D002417:Cattle / Q000378:metabolism*; D000090943:Delta-5 Fatty Acid Desaturase; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis*; D004305:Dose-Response Relationship, Drug; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005229:Fatty Acids, Monounsaturated / Q000008:administration & dosage; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D043371:Fatty Acids, Omega-6 / Q000008:administration & dosage*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D050602:Linoleoyl-CoA Desaturase / Q000378:metabolism; D008043:Linseed Oil / Q000008:administration & dosage; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology*; D010938:Plant Oils; D011897:Random Allocation; D000074262:Rapeseed Oil; D012044:Regression Analysis; D013024:Soybean Oil / Q000008:administration & dosage; D013696:Temperature
chemical_list: D000090943:Delta-5 Fatty Acid Desaturase; D005229:Fatty Acids, Monounsaturated; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D010938:Plant Oils; D000074262:Rapeseed Oil; D013024:Soybean Oil; D008043:Linseed Oil; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase