Dietary Lipid Requirements for Optimal Egg Quality of Redclaw Crayfish, Cherax quadricarinatus

The effect of three crude dietary lipid levels (4, 8, and 12%) on egg quality of the female redclaw crayfish, Cherax quadricarinatus, was evaluated. Three replicate groups of 40 crayfish (mean initial weight +/- SD, 23.0 +/- 3.0 g) per diet treatment were stocked in 15,000 -L tanks, at 28 C. After 75 d of culture, there were significant differences (P < 0.001) in egg area (3.52-3.90 mm(2)), volume (34.0-39.3 mm(3)), weight (4.81-5.36 mg), and diameter (2.15-2.27 mm) in response to dietary lipids in the diet. Using the quadratic equation, the maximum responses of these parameters corresponded to lipid levels from 8.60-8.84%. There were no significant differences (P > 0.05) in survival (82.1-86.9%), final weight (41.0-43.7 g), number of spawning females (18.12-27.38%), and fecundity (9.07-10.31 eggs/g female). Additionally, there were no significant differences (P > 0.05) in egg mean protein (2306.87 +/- 440.08 mu g/egg), lipid (441.95 +/- 83.23 mu g/egg) and carbohydrate (74.81 +/- 10.12 mu g/egg) contents, and energy (13.49 +/- 2.25 kcal/egg). The optimum overall response was obtained for dietary lipid content of 8.7%, which we recommend to optimize egg quality of this freshwater crayfish.