Estimation of maintenance requirements for protein and energy of narrow clawed crayfish (Pontastacus leptodactylus Esch, 1823) using a factorial approach

There is an increasing global interest in aquaculture for producing new species, including the narrow-clawed crayfish (Pontastacus leptodactylus). Developing species-specific feed formulations is crucial for cultivating crayfish under controlled conditions. The factorial approach method was employed in this study to determine maintenance protein and energy requirements, as well as protein and energy utilization efficiency. Crayfish with an initial weight of 0.70±0.02 g were individually housed and fed for 29 days at four feeding levels (starvation, low, medium, and high). Maintenance protein and energy requirements were determined as 1.67 mg/kg body weight0.7/day and 44.77 kJ/kg body weight0.8/day, respectively. Protein and energy utilization efficiency were estimated at 0.413 and 0.279, respectively. Growth potential was estimated using growth data collected from individual chambers and literature, yielding growth (mg/day) = 25.006x0.7512; (R² = 0.8998). As body nutrient composition was not size-dependent, average data were used to estimate nutrient requirements. Protein and energy requirements, along with protein/energy (g/MJ) ratios, were calculated for crayfish up to 50 g. Critical weights where protein/energy requirements change were estimated at 4 and 20 g. Based on requirements, feed specifications are recommended: 20 MJ/kg energy and 57% protein for crayfish up to 4 g, 19 MJ/kg energy and 50% protein up to 20 g, and 18 MJ/kg energy and 45% protein for crayfish between 20 and 50 g. These findings bridge a crucial gap in crayfish cultivation by providing species-specific feed formulations.