Optimal dietary protein/lipid ratio for improved immune status of a newly cultivated Mediterranean fish species, the shi drum Umbrina cirrosa, L.

Shi drum is a new fish species recently cultivated in Greek fish farms. Its feeding requirements and health status must be determined in order to optimize its culture conditions. The present study looked at the effects of different dietary protein levels (47 or 52%) in combination with 3 lipid levels (10, 15 or 20%) on the immune system of juvenile shi drums. Most immune parameters assessed were affected by the dietary treatment. The ceruloplasmin activity, the whole blood respiratory burst activity, the serum myeloperoxidase activity, the antibacterial activity of serum lysozyme and the serum antiprotease activity all varied with the dietary protein/lipid ratio. In view of these results, the lowest dietary lipid level tested (10%) was optimal for the immune system of shi drum but a clear determination of the optimal dietary protein levels was not obtained as 47% reduced stress but also increased the ceruloplasmin response of the fish. A dietary lipid level of 10% lipids was recommended for optimal immune status of the fish. Dietary protein level of 47% seemed to give better immune responses but further study is needed to refine protein requirements.