When balanced for precursor fatty acid supply echium oil is not superior to linseed oil in enriching lamb tissues with long-chain n-3 PUFA

Vegetable oils containing stearidonic acid (SDA, 18: 4n-3) are considered better precursors of long-chain n-3 PUFA (LC n-3 PUFA) than those with only alpha-linolenic acid (ALA, 18: 3n-3). The present study re-examined this premise using treatments where added ALA from linseed oil was matched with ALA plus SDA from echium oil. Lambs (n 6) were abomasally infused with saline (control (C), 25 ml), echium oil low (EL, 25 ml), echium oil high (EH, 50 ml), linseed oil low (LL, 25 ml) or linseed oil high (LH, 50 ml) for 4 weeks. The basal ration used was identical across all treatments. EPA (20: 5n-3) in meat increased from 6.5 mg in the C lambs to 16.8, 17.7, 13.5 and 11.7 (SEM 0.86) mg/100 g muscle in the EL, EH, LL and LH lambs, respectively. For muscle DPA (docosapentaenoic acid; 22: 5n-3), the corresponding values were 14.3, 22.2, 18.6 18.2 and 19.4 (SEM 0.57) mg/100 g muscle. The DHA (22 : 6n-3) content of meat was 5.8 mg/100 g in the C lambs and ranged from 4.53 to 5.46 (SEM 0.27) mg/100 g muscle in the oil-infused groups. Total n-3 PUFA content of meat (including ALA and SDA) increased from 39 mg to 119, 129, 121 and 150 (SEM 12.3) mg/100 g muscle. We conclude that both oil types were effective in enhancing the EPA and DPA, but not DHA, content of meat. Furthermore, we conclude that, when balanced for precursor n-3 fatty acid supply, differences between linseed oil and echium oil in enriching meat with LC n-3 PUFA were of little, if any, nutritional significance.