Implications of dietary phosphorus sources on zootechnical performance and stress response of the pacific white shrimp Litopenaeus vannamei

The phosphorous (P) is an essential element for several functions, including the synthesis of high energy compounds in cells like adenosine triphosphate (ATP) and arginine phosphate (ArgP). The dietary requirements of P could change according to physiological and environmental conditions, particularly if organisms are exposed to stress conditions. As the P availability could be related to its chemical form in the diet, the present study analyzed the influence of different P sources (KH2PO4, NaH2PO4, NH4H2PO4, Na5P3O10), on the stress response of the Pacific white shrimp Litopenaeus vannamei. Final weight was 8.5% higher (p < 0.01) in shrimp fed on tripolyphosphate (Na5P3O10) diet compared with the monophosphate diets. Weight gain and specific growth also trend to increase, whereas feed conversion ratio trend to decrease with this polyphosphate source, although not significantly. Stress response of shrimp exposed to handling followed by hypoxia was characterized by an overall increase of lactate and glucose levels in hemolymph, as well as a decrease in Adenylate Energy Charge (AEC) and ArgP in the muscle. No effect of dietary P sources was observed on baseline biochemical composition and overall indicators of stress response, except for higher carbohydrate levels in hepatopancreas and RNAm expression of arginine kinase (AK) in muscle with the NaH2PO4 diet, suggesting a potentially better energy status with this diet.