EFFICACY OF MARINE SULFATED POLYSACCHARIDE EXTRACT OF GREEN ALGAE, TO ENHANCE SHRIMP Penaeus vannamei IMMUNITY AND RESISTANCE AGAINST WHITE SPOT SYNDROME VIRUS (WSSV)
Immuno-stimulation has been widely acknowledged as a potential approach to prevent and control diseases in shrimp aquaculture. However, studies over its possible overstimulation hasn't been much investigated. Thus, the present paper was conducted to evaluate the immune-modulatory effects of dietary supplementation of marine sulfated polysaccharides (MSPs) extract of green algae Ulva lactuca on pacific white shrimp Penaeus vannamei.
Shrimps of 0,52+0.02g were fed diets supplemented with 0%, 0,2%, 0,4%, 0,8% and a 0,2% equivalent biomass of Olmix MSP® extract for 60 days. Growth and survival were not significantly affected, whereas immune parameters (White blood cell count, Respiratory burst and phenol oxidase activity) were significantly improved indicating that MSP® inclusion in the diet at the given dose and duration of the trial modulate immunity without affecting growth performances. To further investigate the immune modulatory effect of this MSP® extract, an immersion challenge with the LC50 of WSSV was conducted for 11 days. Shrimp survival was found to be significantly higher in groups with supplementation at 0,2% and 0,4%. Protective effect of both doses was further evaluated for 17 days by comparing the survival of the shrimp when feeding with MSP® was continued or halted after WSSV infection. Higher survival was recorded in both groups that received continuous supplementation and, in the group, fed 0,2% that received no further supplementation suggesting that there is a longer protective effect when MSP® is given at 0,4%. These present findings provide proof on the efficacy of the Olmix MSP® extract to modulate P. vannamei immunity when administered at an optimum dosage.
