Effects of dietary calcium, phosphorus and calcium/phosphorus ratio on the growth and tissue mineralization of Litopenaeus vannamei reared in low-salinity water

Abstract

An 8-week feeding experiment was conducted to evaluate the response of juvenile Litopenaeus vannamei to dietary calcium (Ca), phosphorus (P) and their interaction between Ca and P in low-salinity water of No. Fifteen isonitrogenous and isoenergetic diets, containing five graded levels of total P (0%, 0.5%, 1%, 1.5% and 2%) for each of three levels of Ca (0%, 1% and 2%), were fed to juvenile L. vannamei. Prior to the experiment, the postlarvae were gradually acclimated to low salinity and fed a basal diet (0.5% total Ca and 0.5% total P) for 2 weeks. After 8 weeks, survival, hepatopancreas alkaline phosphatase and protein content of muscle were significantly affected by dietary P levels (P < 0.05). The weight gain (WG), ranging from 505.44% to 1187.72%, was significantly affected by dietary Ca, P and the interaction between Ca and P (P < 0.05). In the absence of supplemental Ca, diets containing 0.77% estimated available phosphorus (EAP) (0.93% total P) were adequate for optimal growth. In the presence of 1% supplemental Ca, shrimp fed diets containing 1.22% EAP (2% total P) had better growth performance. The response to dietary P supplementation was dependent on dietary Ca level. Supplementation of 2% Ca to the basal diets yielded a significant reduction in growth, indicating that dietary Ca should be reduced to minimize dietary P supplementation. The Ca, P, magnesium, zinc and manganese content in tissues responded to dietary treatment. However, there was no clear relationship between growth and tissue mineralization. (c) 2005 Elsevier B.V All rights reserved