Physiological aspects linked with dietary fishmeal replacement for Litopenaeus vannamei  

L.vannamei juveniles were maintained in microsome for 70 days with an average weight of 2.6g and dispatched in triplicate. Diets contained 25 to 5% fishmeal (T1 to T5) and a commercial feed as control. Exogenous phytase (0.05%) as well as taurine (1%) was added to follow the  increment of plant protein sources. In spite of phosphorus requirement that has been eludicated before, however it takes recent concern with the replacement of fishmeal by plant proteins. Therefore, a set of diets containing a progressive amount of plant protein sources wa surveyed on juveniles, and it produced some slight changes in blood parameters such as hemocyte count (2.3-2.9 10⁶), SOD (9-10 U mg protein^-1) (p>0.05). Weight gain (0.7g week^-1) or survival (70-92%) were modified significantly (p<0.05), phytate tended to compensate some negative effects by a change in digestive enzymes, and in final a satisfactory reduction of fishmeal content was noticed; homeostasis remained stable for the time juveniles were surveyed. Some particular elements of the diets could have contributed to such replacement such as taurine while mineral part did maintain certain supply of phosphorus (around 1% P available) even though more percent could have been benefited to weight gain and especially molting frequency. There is definitely a progress in this field of fishmeal replacement in view of the fact that shrimp shear strength (69-81mJ) remained  in an acceptable range on a short term study.