CHANGES IN THE FATTY-ACID PROFILES OF HYBRID RED TILAPIA, OREOCHROMIS-MOSSAMBICUS X OREOCHROMIS-NILOTICUS, SUBJECTED TO SHORT-TERM STARVATION, AND A COMPARISON WITH CHANGES IN SEAWATER RAISED FISH

Juvenile hybrid red tilapia of mean weight 52.9 +/- 2.80 g were starve d for 45 days, and the liver and muscle fatty acid profiles of fed and starved fish determined on Days 0, 24 and 45. A corresponding group o f fish were seawater adapted and were sampled on Day 45. In fed fish t he total fatty acids in the livers (expressed in mu g mg(-1) lipid) de creased with growth (45 days), from 816 +/- 16 to 600 +/- 7 and 821 +/ - 25 to 589 +/- 23 in fi-males and males, respectively. This decrease was significant by the 24th day. Tn muscle, however, the amount of fat ty acids in total lipid increased with growth, in females from 365 +/- 21 to 489 +/- 6 and in males from 387 +/- 17 to 480 +/- 17 mu g mg(-1 ) lipid. Compared with fed fish, during starvation the proportion of f atty acids in total lipid increased in both types of tissues but was s till lower than at the initial level, significantly so in the liver. T wenty individual fatty acids were quantified as percent of total fatty acids in liver and muscle tissues of fish from different treatments d uring this study. In starved fish, liver monoenes decreased significan tly (P < 0.05), from 33.0 to 16.3% and 35.6 to 9.5%, and the percentag e of polyunsaturated fatty acids (PUFA) increased significantly from 1 8.3 to 39.9% and 16.9 to 46.2% in females and males, respectively. Com parable trends were also observed in muscle, but in muscle the percent age of PUFA tended to be higher than in the liver. The fatty acids tha t occurred in the highest proportion were oleic acid (18:1n - 9), foll owed by palmitic acid (16:0) and docosahexaenoic acid (DHA; 22:6n - 3) , collectively accounting for more than 50% of the total. The relative amount of PUFA, in particular DHA, increased considerably and very si gnificantly with starvation. Principal component analysis of the fatty acid data effectively summarized the major differences among the expe rimental treatments, which included substantial differences in the fat ty acid profiles between sexes, fed and starved animals and between fi sh raised in fresh- and seawater. (C) 1997 Elsevier Science B.V.