Submitted on July 12, 2007
Revised on August 9, 2007
Accepted on August 16, 2007
Artificial rearing with docosahexaenoic acid and n-6 docosapentaenoic acid alters rat tissue fatty acid composition
Ken D. Stark, Sun-Young Lim, and Norman Salem Jr.
Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1
Corresponding Author: kstark{at}uwaterloo.ca
Docosahexaenoic acid (22:6n-3, DHA) and n-6 docosapentaenoic acid (22:5n-6, DPAn-6) are components of enriched animal feed and oil derived from Schizochytrium sp. microalgae. A one generation, artificial rearing model from d2 after birth onward (AR) and a dam reared control group (DAM) was used to examine DPAn-6 feeding on the fatty acid composition of various rat tissues at 15 wks of age. Four AR diets were based on an n-3 fatty acid deficient, 18:2n-6 based artificial milk with 22:6n-3 and/or 22:5n-6 added; AR-LA, AR-DHA, AR-DPAn-6, AR-DHA+DPAn-6. The 22:6n-3 levels for the DAM, AR-DHA and AR-DHA+DPAn-6 groups tended to be similar, and higher than in the AR-LA and AR-DPAn-6 groups. The levels of 22:5n-6 tended to be higher only in the absence of dietary 22:6n-3. Adipose levels of 22:5n-6 was the only exception as 22:5n-6 was significantly higher in AR-DHA+DPAn-6 than was observed in either the DAM or AR-DHA groups. There were no differences in 20:4n-6 levels within the tissues examined. In conclusion, 22:5n-6 replaces 22:6n-3 in the absence of 22:6n-3 only and does not appear to compete with 22:6n-3 in the presence of dietary 22:6n-3, suggesting that oils containing 22:5n-6 and 22:6n-3 may be a good dietary source of 22:6n-3.
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