The dietary effect of fucoidan extracted from brown seaweed, Cystoseira trinodis (C. Agardh) on growth and disease resistance to WSSV in shrimp Litopenaeus vannamei.

The polysaccharide-fucoidan plays a fundamental role in shrimp aquaculture by being used as a natural immunostimulant and dietary supplementation. In this study, Cystoseira trinodis fucoidan (FCT) was extracted, its structure was determined using FT-IR analysis, and its effect of fucoidan on growth performance and WSSV resistance in Litopenaeus vannamei was evaluated. Four experimental diets, including the control (without FCT), 0.1, 0.2, and 0.4% FCT, were formulated and fed to shrimps for 60 days. Next, they were exposed to WSSV, and their mortality rate was noted daily up to 20 days. The results of the growth experiment demonstrated a significant increase in the final weight, WG, and SGR, and a lower FCR in treatments than in control. During the challenge trial, 100% mortality was recorded in control within ten days. However, FCT-treated shrimps indicated a mortality increase from 43.33 to 75.00% during 20 days of infection. The immunological and biochemical parameters and the expression of immune-related genes in individuals fed the FCT-incorporated diet considerably (p < 0.01) improved over control before the challenge (0 days) and after the challenge on days 5, 10, 15, and 20. It was concluded that L. vannamei fed on diets supplemented with all concentrations of FCT (especially 0.4%) had improved the growth, immunological and biochemical parameters, and the expression of immune-related genes, as well as enhancing the resistance against WSSV.
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