Evaluación De La Harina De [Spirulina Platenses] Como Alimento Y Aditivo Para La Producción De Postlarvas De Camarón Blanco [Litopenaeus Schmitti] (Pérez-Farfante Y Kensley, 1997)
Jaime Ceballos, B.
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The high cost of using live microalgae and the variations in nutritional value during larval culture constitute a problem for any operation relying on the massive culture of unicellular microalgae. The price of Artemia cysts in the international market and the increasing demand in Cuba, due to the development of the shrimp culture industry, has made the search of feeding alternatives that can of satisfactory diminish the live food consumption in shrimp larviculture, essential. Spirulina platensis meal (SPM), produced commercially in Cuba, has optimal nutritional characteristics to be used as a food ingredient in any aquatic animal culture. For that reason in this thesis we set out to improve the efficiency in the production of Litopenaeus schmitti shrimp postlarvae, through the inclusion of SPM in the feeding schedule by testing it: a) as substitute of fitoplanctonic food in the protozoea stage; b) feed additive in microparticulates in order to replace Artemia nauplii in mysis and postlarvae feeding; and c) as an attractant in feeds for juveniles. Four experiments were carried out at the Yaguacam Hatchery, Cienfuegos Province, Cuba, using a completely randomized experimental design. In the first trial, Chlorella vulgaris, Dunaliella saline and two stocks of Spirulina sp. (GENIX and EARTHRISE) meals were fed in triplicates to protozoea. The control consisted of a combination of Chaetoceros muelleri, Thalasiossira fluviatilis and Tetraselmis tetrathele. The results demonstrated that L. schmitti larvae consume micralgae meal, with similar results obtained from the combination of SPM with live micralgae and the control. Spirulina platensis meal (SPM) from GENIX promoted the best results in final length, development index and survival. A second experiment evaluated the nutritional response of L. schmitti larvae to different substitution levels (S) of Chaetoceros muelleri by SPM (0, 25, 50, 75 and 100 %). Final larval length (FL) varied from 1,98 to 3,16 mm, with a significant relationship between the level of substitution (S) and FL, described by the equation: FL = 2,853 + 0,01598 S - 0,000233 S2 (p<0.01). Optimum substitution level was 34.2%. The development index (DI) varied between 2.84 and 3.93 depending on the substitution level (S). The equation was ID= 3.799 + 0.00945 S – 0.000189 S2 (p<0.01), with a maximum DI value at 25% substitution. Survival was high for all treatments (82-87%). From the results it can be suggested a substitution level of C. muelleri by SPM of 30% to obtain simultaneous improvement in FL and DI. In the third experiment, SPM was included as feed additive (0, 2.5 and 5%) in microparticulate diets for mysis and tested in triplicate. Artemia nauplii were used as control. DI was higher when SPM level increased, with a significant realtionship between these two factors (r2= 0.98). Larvae that consumed live food and the 5% SPM diet had similar survival and DI than the control. Nevertheless, those that consumend feeds with 0 and 2.5% SPM were smaller (p<0.05) than the control. The chemical score of the three microparticulates showed that diets were similar in protein composition and the L. schmitti postlarvae aminoacid pattern. Results suggest that it is possible to use the 5% SPM microparticulate as partial substitute of Artemia nauplii. The fourth experiment consisted of determining the optimal Artemia nauplii substitution level by SPM5. Five treatments with three replicates were applied, where 0, 25, 50, 75 and 100% of the Artemia rations were replaced by the SPM5 microparticulate. The DI varied from 6.15 to 6.68 for the different levels of substitution (S). The relationship between both factors was described by the broken line method as DI= ((6,82556) + 0*S)*(S<=(7.) + ((8,31) + (-,18)*S)*(S>7). The intercept of the straight lines indicated that the optimal substitution value of Artemia nauplii by microparticulate food is 66.6%, corresponding to the combination of 8 rations of microparticulate and 4 of Artemia per day. In the fifth experiment the capacity of Spirulina meal as attractant was evaluated at the Fisheries Research Center laboratory in Habana, Cuba, with 4 treatments and 6 repetitions, where two foods and two positions of the food were evaluated. The experimental device consisted of a rectangular aquarium with two glass divisions, that allowed the aquarium to be divided in three equal compartments. Ten Litopenaeus schmitti shrimp (average weight 0,503 ± 0,018 g) were placed in the central section, and had access to the other two compartments of the aquarium, where the experimental foods were placed; one with 5% of SPM, and a control without SPM. The results showed that food containing SPM was more attractive for this species, concluding that is possible to improve the attractability of foods for shrimp with the inclusion of 5 % of SPM and that the use of this experimental device allows to evaluate the attractability of shrimp diets.
- 2. Tesis (CIP)