A 50-day growth trial was conducted to evaluate the efficacy of Chlorella vulgaris (Beijerinck) as an ingredient in the diets of giant freshwater prawn Macrobrachium rosenbergii (De Man) postlarvae (PL30). Immune response (total haemocyte count and prophenoloxidase activity) was also assessed by subjecting postlarvae to a challenge test against Aeromonas hydrophila (Chester) for 14 days. Isonitrogenous and iso-lipidic test diets were prepared using a fishmeal-based-positive control diet (D0) and four basal diets with inclusion levels of 2% (D2), 4% (D4), 6% (D6) and 8% (D8) C. vulgaris. Postlarvae of M. rosenbergii were randomly stocked (mean initial body weight of 0.19 AE 0.02 g) in 30-L tanks in three replicates per dietary treatment for evaluation of growth performance. Another set of postlarvae (mean initial body weight of 1.25 AE 0.02 g) was randomly distributed in 95-L tanks in three replicates per dietary treatment for the assessment of immune response. Results showed that specific growth rate was significantly higher (P < 0.05) in postlarvae fed D4 and D6. Variations in values for carcass protein, lipid, moisture and ash were also evident. Postlarvae fed diets with Chlorella showed increased prophenol oxidase activity and total haemocyte counts. Moreover, survival rate after challenge with A. hydrophila was significantly increased (P < 0.05). Inclusion of C. vulgaris in diets enhanced immune response and resistance of M. rosenbergii postlarvae against A. hydrophila infection.

A feeding trial was conducted to evaluate the effects of Spirulina (Arthrospira platensis) inclusion in experimental diets of juvenile Nile tilapia (Oreochromis niloticus). Iso-nitrogenous and iso-lipidic diets were prepared using a positive control diet (S0) and four basal diets with A. platensis at 30 % (S30), 45 % (S45), 60 % (S60), and 75 % (S75) inclusion levels. Experimental diets were randomly assigned to tanks (13.35 kg m −3 ) with initial body weight of 0.89±0.02 g in triplicates.The results of the feeding trial demonstrated significantly improved (P < 0.05) growth performance and hepatosomatic and viscerosomatic indices of fish fed S30. Blood chemical profile also indicated desirable values in fish fed A. platensis diets as compared to fish fed S0. On the contrary, fish fed S75 exhibited significantly reduced fish growth. Blood chemical analysis showed significant difference (P<0.05) in levels of plasma triglyceride. Results of the present work indicate that 30 % A. platensis inclusion is deemed the optimal level of dietary replacement for increased growth performance, improved feed utilization efficiency, and enhanced overall health status of Nile tilapia juveniles.

A feeding trial was conducted to evaluate the influence of dietary supplementation of Undaria pinnatifida fucoidan on growth performance and immunological response of juvenile Marsupenaeus japonicus. Four semipurified diets supplemented with graded levels of fucoidan (0.0, 100, 500, and 1000 mg/kg diet) were fed to juvenile shrimp for 8 wk. Each diet was fed to three replicate groups of shrimp. At the end of the feeding trial, enhanced growth performance was generally observed in shrimp fed the fucoidan‐supplemented diets when compared with the shrimp fed the control diet. Significantly higher weight gains, specific growth rates, protein retentions, and lower feed conversion ratios were observed in treatment groups fed the 500 and 1000 mg/kg dietary fucoidan supplementation when compared with the treatment groups receiving 100 mg/kg fucoidan supplementation and the control diet. Total hemocyte counts, phenol oxidase activity, and serum antibacterial activity were also significantly enhanced in shrimp fed diets supplemented with 500 and 1000 mg/kg fucoidan supplementation. These results suggest that U. pinnatifida fucoidan at a dose of 500 mg/kg diet could be used as an immunostimulant and a growth‐promoting dietary supplement for juvenile M. japonicus.

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A feeding trial was conducted to determine the effect of phytic acid (IP6) on growth, feed intake, nutrient digestibility, body composition, nutrient retention, and plasma mineral contents in juvenile Japanese flounder, Paralichthys olivaceus. Five test diets containing different levels of IP6 (0, 5.1, 10.4, 13.5, and 20.6 g IP6/kg diet) were fed to juveniles (average body weight = 4.58 g). After a 50-d feeding trial, there were no negative effects on growth and feed intake in fish fed diets supplemented with IP6 up to 10.4 g IP6/kg. However, weight gain and feed intake of fish fed diets containing 13.5 and 20.6 g IP6 were significantly lower than those of control group. Total phosphorus (P) contents of fish were not significantly different among fish groups fed the diets containing up to 10.4 g IP6. Plasma inorganic P and magnesium (Mg) contents significantly lowered with increased dietary IP6. Dietary IP6 significantly reduced zinc level in the fish vertebra. The significantly lower contents of vertebral Ca and Mg were found in fish fed diets containing the highest level of IP6 (20.6 g/kg). This study demonstrated that dietary IP6 with more than 13 mg/kg negatively affected the growth performances, body composition, and nutrient utilization in juvenile Japanese flounder.