Effect of dietary protein-to-energy ratio on reproduction in female redclaw crayfish Cherax quadricarinatus

The effect of eight diets with different protein-to-energy ratios (P-E ratio=10, 11, 14, 16, 18, 20, 22, 24mgkJ^-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 16.0mgkJ^-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 18.6mgkJ^-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 20.2mgkJ^-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±2mgkJ^-1 is optimal for reproductive activity of female redclaw crayfish.