Effect of dietary macro-algae in diet of juvenile Pacific white shrimp Litopenaeus vannamei

An 8-week feeding trial was conducted to evaluate the effect of dietary macro-algae in diet of juvenile Pacific white shrimp, Litopenaeus vannamei. The five macro-algae ingredients, including Saccharin japonica, Porphyra dioica, Gracilariopsis lemaneiformis, Ulva lactuca, and Undaria pinnatifida, were used for test diets, named SJD, PDD, GLD, ULD, and UPD, respectively. A reference diet (RD) and five test diets (30% test ingredients and 70% RD) were formulated. Each diet was randomly assigned to triplicate groups of 40 shrimp (initial body weight, 2.00 +/- 0.01 g) and the shrimp were hand fed four times a day to apparent satiation. During the last 2 weeks, the fecal samples were collected by siphoning. The results showed that among five test diets, shrimp fed the SJD had the highest weight gain and the lowest feed coefficient, shrimp fed the SJD and GLD shared the same survival ratio and were significantly higher than shrimp fed the PDD and UPD (p < 0.05). For the composition of whole body, shrimp fed the SJD had the highest protein and lipid content compared with the shrimp fed other test diets. Apparent dry matter digestibility from high to low was: P dioica, S. japonica, G. lemaneiformis, U. lactuca, and U. pinnatifida. Apparent protein digestibility of five macro-algae was highest in U. pinnatifida and lowest in G. lemaneiformis. Additionally, the highest apparent digestibility of gross energy was found in P. dioica. Apparent digestibility of total phosphorous in five ingredients was generally low and highest in S. japonica which was significantly higher than other ingredients (p < 0.05). These results indicated that S. japonica is more suitable for feed ingredient than other four kinds of macro-algae.