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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 mm2), volume (34.0–39.3 mm3), 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 μg/egg), lipid (441.95 ± 83.23 μg/egg) and carbohydrate (74.81 ± 10.12 μg/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.

The effect of five experimental diets with different crude protein content (220, 270, 330, 390 and 450 g kg )1 ) on gonad development of female Cherax quadricarinatus was tested under laboratory conditions. After 70 days, a significant linear relationship indicated that higher concentrations of protein and carbohydrates in the hepatopancreas were produced as the dietary crude protein increased (P < 0.05). There were significant responses of the gonadosomatic index, hepatosomatic index, biochemical composition of the gonad (protein, lipids, carbohydrates and energy) and frequency of secondary vitellogenic oocytes to dietary protein level, as indicated by significant fits of the quadratic equation to the observed experimental data. The optimal response of the criteria parameters corresponded to levels of crude protein in the range 284-355 g kg )1 . Overall, 330 g kg )1 crude protein with a protein : energy ratio of 15.6 mg kJ -1 was considered the most adequate concentration of dietary protein for gonad development and biochemical composition in female redclaw crayfish. KEY WORDS