Losses of lipid, protein and n-3 fatty acids in enriched Artemia franciscana starved at different temperatures

The loss rates of protein and lipids were determined for enriched Artemia f ranciscana starved at different temperatures after enrichment. Following 12 -h enrichment with DHA Selco (0.2 g l(-1)) at 28 degreesC, the nauplii were temperature acclimated and transferred to starving condition (0-96 h; 5 de greesC to 30 degreesC). The total lipid content during enrichment increased from 145 mg g(-1) dry w eight (DW) (newly hatched nauplii) to 222 mg g(-1) DW after 12 h. The DHA/E PA ratio reached an optimum after 12 h (1.85), where DHA and EPA constitute d 12% and 6.7% of total fatty acids, respectively. When the nauplii were transferred to starving conditions the contents of al l lipid components became reduced. The specific loss rate was found to be e xponential for all components and significantly higher for DHA than for EPA and the sum of the other n - 3 fatty acids. A. franciscana starved at the highest temperature (30 degreesC) showed a loss rate of 92% day(-1) (of DHA ). Nauplii starved at 12 degreesC had a loss rate of 51% day(-1) (of DHA). At the same temperature (12 degreesC) the corresponding loss rate of EPA, t he sum of the other n - 3 fatty acids and for the total lipid content was 1 5%, 30% and 11% day(-1), respectively. The protein content was relatively stable in the nauplii kept at the lowest temperatures (5 degreesC and 8 degreesC), but as temperature increased, th e loss rate of protein gradually increased reaching a loss rate of 28% day( -1) in nauplii starved at 26 degreesC. The survival of the nauplii was > 67 % throughout the starvation period (96 h), but at temperatures below 8 degr eesC and above 19 degreesC, the survival was < 13% after 96 h. Results show that the when Artemia nauplii are starved the lipid and protei n content decreases as a function of temperature. This might affect the nut ritional value of A. franciscana quite strongly if the nauplii reside in th e fish tanks before being eaten by the larvae, or stored at ambient tempera ture before they are transferred to the fish tanks. (C) 2001 Elsevier Scien ce B.V. All rights reserved.