Research Information System
Turkish Journal of Zoology, vol.49, no.4, pp.220-232, 2025 (SCI-Expanded, Scopus, TRDizin)
This study investigated the impact of different levels of Codium fragile macroalgae (CF) dietary supplementation combined with a fixed concentration of 0.05% fennel (Foeniculum vulgare Mill. var. dulce Mill.) essential oil (FO) on the growth performance, enzyme activity, and hepatopancreas histological changes of juvenile narrow-clawed crayfish Pontastacus leptodactylus (initial average weight = 0.25 ± 0.04 g). A 90-day feeding trial was conducted using four experimental groups: CF + FO (control), 1% CF + FO, 2% CF + FO, and 4% CF + FO. The essential oil yield obtained from the fennel seeds was 2.4%. Anethole was the most abundant component of FO (79.14%), followed by estragole (9.21%), limonene (3.49%), and p-anisaldehyde (2.75%). Fifteen crayfish per tank were stocked in 30 L plastic tanks, with three replicates for each treatment. The results showed that juvenile crayfish in the 1% CF + FO group showed the best growth performance (2.26 ± 1.30 g), weight gain (2.03 ± 1.24 g), protease activity (567.80 ± 13.71 U/mg protein), and the lowest feed conversion ratio (1.32 ± 0.30) (p < 0.05). The highest protein (13.40%) and lipid (2.0%) contents were also observed in the 1% CF + FO group. Dietary supplementation with 1% CF + FO improved the histomorphology of the hepatopancreas. In contrast, supplementation with 4% CF + FO caused histomorphological alterations, including hepatocyte vacuolation, tubule enlargement, and cellular fractionation. In conclusion, supplementation of the diet with 1% CF and 0.05% FO significantly enhances growth performance, stimulates digestive enzyme activity, and improves the hepatopancreas histological structure in juvenile P. leptodactylus.