Dietary phosphorus requirement of red swamp crayfish (Procambarus clarkia)
2022
Xu, Lei | Chen, Xiaoru | Wen, Hua | Wu, Fan | Zhang, Wenbing | Gao, Weihua | Tian, Juan
To evaluate dietary phosphorus requirement of red swamp crayfish (Procambarus clarkia), six diets containing different concentrations phosphorus (2.7, 6.6, 10.5, 14.6, 18.3 and 22.5 g kg⁻¹ diet respectively) were prepared. Each diet was assigned to triplicate of 15 crayfish (initial mean weight: 9.33 ± 0.54 g) for 56 days. The weight gain rate (WGR) significantly increased when dietary phosphorus content increased from 2.7 to 14.6 g kg⁻¹ (p < 0.05), and the feed conversion ratio (FCR) showed an opposite tendency as observed in WGR. As dietary phosphorus level increased, the muscular ash content, the content of calcium and phosphorus in muscle and shell, the inorganic phosphorus concentration in serum, and the protease activities in intestine and hepatopancreas significantly increased (p < 0.05), while the muscular crude lipid content, the lipase activities in intestine and hepatopancreas, the malondialdehyde concentration in hepatopancreas, and the concentrations of total cholesterol, triglyceride and parathyroid hormone in serum significantly decreased (p < 0.05). When crayfish fed diet with phosphorus content from 10.5 to 14.6 g kg⁻¹, the activities of amylase in intestine and hepatopancreas, the activities of catalase in hepatopancreas and the concentration of total antioxidant capacity in hepatopancreas significantly increased (p < 0.05). Broken‐line model analysis in terms of the WGR and FCR indicated that optimal dietary phosphorus requirement of crayfish was from 13.9 to 14.3 g kg⁻¹. The signs of phosphorus deficiency for red swamp crayfish were characterized by poor growth, slightly reduced mineralization and increased body lipid deposition.
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