15 DECEMBER 1999
G.J.I. Arango, J. Torres de Leon, M. Carrera, F. Lucas
In the Regional Center for Aquaculture Research, Roche & Cachugran, two projects were developed, to investigate the use of pre-mixed vitamins in shrimp feeds. The main objective was to evaluate, with scientific precision, the effect of these diets on the semi-intensive commercial farming practices. The first project was carried out in September and October 1997, to estimate the effect of two pre-mixed vitamin diets, of medium and high vitamin content, on the main zootechnical indexes in the production of L. vannamei shrimp PL 12 to 4.0 g live weight, stocked at 16.4 PL's/m^2. In the second project, carried out in April and May 1999, the results of using and not using a high vitamin diet, on L. vannamei shrimp PL 12 to 5.0 g, stocked at 18 PL's/m^2, were compared. The main production indexes were again analyzed.
In the two projects, significant results were obtained, when high vitamin diets were used , with probabilities between p < 10 and p < 0.005, in the number of shrimp being harvested, the survival rate, the total harvested weight and feed conversion rate. Finding better survival rates in both projects, even with evidence of diseases, eg vibriosis and/or gregarines, and without the use of antibiotics to treat them, suggests that the shrimp fed the high vitamin diets, could not only meet their nutritional requirements, but developed a higher resistance to the diseases present in the environment.
In both projects, no significant differences were noticed, between the treatments regarding the main parameters being evaluated in the water column, either physical (temperature, oxygen, salinity and secchi disc) or the phytoplankton (total cell concentration, diatoms, cyanophytes and chlorophytes). Low significant variations were observed on the zootechnical indexes: number of shrimp being harvested, survival, feed conversion rate, final weight and total harvested weight, which indicates that both projects were well managed field experiments and that the data were reliable.
In both research projects, it was demonstrated that the vitamin content in the primary production wasn't enough to support higher production levels in the initial stages of production of L. vannamei shrimp PL 10 to 5.0g, stocked between 16.4 and 18 PL's/m^2 and harvested between 9 and 14 shrimp/m^2 with a live weight of 4.0 to 5.0 g.