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

The eiect of eight diets with diierent protein-to-energy ratios (P^E ratio 510, 11, 14, 16, 18, 20, 22, 24 mg kJ � 1 ) on reproduction of female redclaw cray¢sh Cherax quadricarinatus was tested under laboratory conditions. After 75 days, there was a signi¢cant eiect of the P^E ratio on ¢nal 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 signi¢cantly aiected 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 signi¢cantly 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 signi¢cant diierences 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 � 2m g kJ � 1 is optimal for reproductive activity of female redclaw