• protein to energy ratio;
  • reproduction;
  • Cherax quadricarinatus


The effect of eight diets with different protein-to-energy ratios (P–E ratio=10, 11, 14, 16, 18, 20, 22, 24 mg kJ−1) on reproduction of female redclaw crayfish Cherax quadricarinatus was tested under laboratory conditions. After 75 days, there was a significant effect of the P–E ratio on final weight, spawning females and the number of juveniles per female. Using the broken-line and quadratic equations, optimal values for the P–E ratio were: 16.0, 17.1 and 16.0 mg kJ−1. The P–E ratio significantly affected protein and carbohydrate content and energy in the hepatopancreas. The broken-line model indicated that the respective recommended values of the P–E ratio for these parameters were: 21.8, 16.7 and 18.6 mg kJ−1. The concentration of carbohydrates and energy in muscle tended to significantly diminish as the P–E ratio increased. From broken-line regression analysis, the recommended P–E ratio was 16.6 and 20.2 mg kJ−1 respectively. No significant differences were found in survival, fecundity, vitellin content in eggs, protein and lipid content in muscle and lipids in the hepatopancreas. We concluded that, overall, a P–E ratio of 18±2 mg kJ−1 is optimal for reproductive activity of female redclaw crayfish.