Shrimp/Ulva co-culture: A sustainable alternative to diminish the need for artificial feed and improve shrimp quality

Juvenile shrimp Litopenaeus vannamei (3.5 g initial weight) and green seaweed Ulva clathrata were co-cultured in outdoors tanks (2000 L) for 45 days; co-cultured Ulva was suspended on a mesh stretched on the water surface. Four dietary treatments were evaluated: Ulva alone, Ulva + 55% feed ration, Ulva + 90% feed ration, and 100% feed ration (control group without co-cultured Ulva). The control group was fed a commercial pellet (30% protein, 8% fat) at a daily ration of 3.5% shrimp biomass. Water turbidity in co-culture tanks was lower than that in control group. Survival was similar among the experimental groups (>80%). The Ulva intake by shrimp improved the artificial feed conversion ratio and the growth rate: with 10 or 45% less commercial feed, growth rate improved by 60%. Additionally, U. clathrata intake diminished lipids content in shrimp carcass and also modified the fatty acids profile. Shrimp body carotenoids content was significantly higher in the co-culture groups, suggesting that Ulva carotenoids were efficiently assimilated and metabolized, and also may be involved in growth enhancement.