Gracilaria domingensis as an immunostimulant for juvenile mullets Mugil liza (Valenciennes, 1836)
Seaweed is widely used in human and animal nutrition, as it is a source of several compounds that bring health benefits as immunostimulants, since they have several bioactive compounds, including macro and micronutrients. The aim of the present study was to evaluate the effect of including the macroalgae Gracilaria domingensis on zootechnical parameters, leukocyte profile and CD3 and CD4 markings in the spleen of juveniles of the Mugil liza mullet. Five diets were tested with increasing levels of G. domingensis (0, 5, 10, 15 and 20%). Mullet juveniles (0.42 ± 0.03g) were stored in 15 tanks. Feeding was offered four times a day, until apparent satiety, during an experimental period of 60 days. The results of the experiment showed that fish from treatments with 0, 5 and 10% G.domingensis had better zootechnical performance indexes such as weight gain, apparent feed conversion (CAA) and specific growth rate (TBI). There was no significant difference in body chemical composition and differential white blood cell count in fish in all treatments. Significant differences were found in the marking of T lymphocytes by anti-CD3 and anti-CD4 techniques in the spleen, between animals fed the control diet and diets containing macroalgae inclusions. We can conclude that the inclusion of the macro algae G. dominigensis in the diets of juveniles of mullet M. liza with an inclusion level of up to 5% does not harm the animal's zootechnical performance. Presenting immunostimulation with only 5% of the inclusion of G. domingensis in the diet.