Substitution of Chaetoceros muelleri by Spirulina platensis meal in diets for Litopenaeus schmitti larvae

The nutritional response of Litopenaeus schmitti larvae to substitution of Chaetoceros muelleri by Spirulina platensis meal (SPM) was evaluated. The substitution levels (S) were 0%, 25%, 50%, 75% and 100%, dry weight basis. Final larval length (FL) ranged from 1.98 to 3.16 mm for the different substitution levels. There was a significant relationship between S and FL, described by the following quadratic equation: FL=2.853+0.01598S-0.0002335(2). The substitution level (S) yielding maximum FL was 34.2%. Development index (DI) values ranged from 2.84 to 3.93 and were dependent on substitution level. The corresponding equation was DI=3.799+0.00945S-0.000189S(2) (P < 0.01). Maximum DI was obtained at 25.0% substitution. Survival was high (82-87%) and no significant differences were found between treatments. Protein digestibility of either microalgae was high, with 92% for SPM and 94% for C muelleri, with no significant differences between them. The results in this study indicate that an adequate balance of nutrients in relation to the requirements of the species is critical. To simultaneously improve FL and DI, a 30% substitution of C. muelleri by SPM is suggested. This is equivalent to feeding 0.15 mg larvae(-1) day(-1) dry weight basis of a 70% C muelleri/30% SPM diet, representing 0.078 mg protein larvae(-1) day(-1), 0.026 mg lipids larvae(-1) day(-1) and 2.732 J larvae(-1) day(-1). (c) 2006 Elsevier B.V All rights reserved.