Omega-3 and omega-7 oil supplementation on tissue fatty acid accumulation

Eighteen Southdown ewe lambs (42 + 5.6 kg BW) were used to assess the effects of n-3 and n-7 oil supplementation on tissue accumulation of these fatty acids. Lambs were blocked by weight and randomly assigned to one of three treatments: 1) control (CON), no oil supplement, 2) flaxseed oil (FLAX; 56% C18:3 n-3) supplementation at 0.1% of BW, or 3) Provinal® oil (PO; 56% C16:1 n-7) supplementation at 0.1% of BW. All lambs were fed ad libitum the same basal diet consisting of 75% soybean hull pellets and 15% alfalfa pellets. Lambs were fed the treatment diets for 60 d individually. Overall average daily gain was reduced by PO compared to FLAX (P < 0.05). Hot carcass weights were also reduced by 12% for PO vs. FLAX (P < 0.05). Lambs in the PO treatment had a lower (P < 0.01) dressing percentage than CON or FLAX. Total lipid content of the LM was highest (P < 0.05) for FLAX and lowest (P < 0.05) for PO. Supplementation with PO increased palmitoleic (C16:1 n-7), cis-11 vaccenic (C18:1 cis-11), eicosapentaenoic (C20:5; EPA, n-3), and docosahexaenoic (C22:6; DHA, n-3) acids compared to CON or FLAX (P < 0.01). Supplementation of FLAX increased linolenic (C18:3 n-3) acid compared to CON or PO (P < 0.1). These changes in individual fatty acid concentrations with oil supplementation resulted in increased (P < 0.01) omega-3 fatty acid concentrations (+69%) and a lower (P..?) ratio of n-6 to n-3 compared to CON (3.13 for FLAX and PO vs. 5.02 for CON). In conclusion, supplementation with PO increased palmitoleic acid (+95%), cis-11 vaccenic acid (+77%; a known elongation product of palmitoleic acid), EPA (+104%), and DHA (+150%) compared to CON or FLAX. Flaxseed oil supplementation increased linolenic acid (+113%) but did not further convert this n-3 fatty acid into EPA, DPA, or DHA.