15 DECEMBER 1999
R. Wouters, P. Lavens, J. Calderon
In previous studies it has been shown the potential of Artemia biomass to induce maturation in Penaeus vannamei broodstock and increase larvae quality. Since Artemia biomass is used as a fresh frozen product, there are sales and storage problems, so it was considered appropriate to try an Artemia meal and verify its effects on the reproductive performance of the shrimp. Some freeze dried Artemia biomass was obtained (INVE Aquaculture, USA), and incorporated into an experimental artificial maturation diet. The development of artificial diets able to replace as much fresh feeds as possible is a priority. By using artificial diets, the problems involved with the use of fresh can be avoided and components such as antibiotics and hormones can be added. Finally, artificial diets allow a better control in the supply of essential nutrients. In this presentation, the results obtained in various experiments using artificial diets as 50% of the feeding regime of P. vannamei broodstock will be discussed.
The results obtained by replacing 50% of the fresh feeds are promising, however the animal response was not similar in all the experiments. It was observed that the reproductive performance (number of hatches and fertility) and larvae quality (% of nauplii 2-3 metamorphosis to zoea 1) were superior to the 50% artificial diet experiment when compared to the fresh feed treatment. In some other cases no differences were detected between the treatments. In an attempt to increase the level of substitution, good results on gonadal maturation were obtained with as much as 75% of artificial feeds.
In pond broodstock, almost all the parameters evaluated turned out with better results when the Artemia meal diet was used, showing that this meal was an important component to induce ovary maturation, to promote copulation and consequently the hatching, to improve egg fertilization and their quality as well as the quality of the larvae in its first stages. In wild broodstock there was no significant difference in the results. Another result from the use of the Artemia meal in the diets was the considerable increase of the consumption of artificial diets by pond and wild broodstock. Until now the compound in Artemia responsible for this effect on the maturation process has not been determined, however it is interesting to note that it is still active even after the freeze drying process and the preparation of the artificial diet.
(Fundacion CENAIM - ESPOL, Guayaquil, Ecuador)