Enrichment of Artemia with highly unsaturated fatty acids in the larviculture of Farfantepenaeus paulensis and performance in the later stages of cultivation
Groups of larvae of the pink shrimp Farfantepenaeus paulensis were fed from the stage of missis I up to eight days after metamorphosis (PL8) with two different diets: enriched treatment (TE), in which the larvae received Artemia metanáplios enriched with an emulsion rich in highly unsaturated fatty acids (n-3 HUFA), and control treatment (TC), where the larvae were fed with newly hatched Artemia nauplii. The larvae were bred at a density of 67 / L in two 180L tanks. PL8 were submitted to salinity and total ammonia (N-AT) tolerance tests. At the end of larviculture, post-larvae aged 18 days (PL18) were stored at a density of 300 PL / m² in cages (1m2 of bottom and 1.5mm mesh) installed in the Lagoa dos Patos estuary, RS, where they were created during 30 days.PL8 fed enriched Artemia showed significantly higher tolerance to salinity and total ammonia. Lethal salinities for 50% of the population for 24 hours (SL50 24h) were estimated at 18.93 ‰ and 20.53 ‰ for TE and CT, respectively, while lethal concentrations of total ammonia for 50% of the population for 24 hours (LC50 24 h) in TE and TC were 32.6 and 30.0 mg / L N-AT, respectively. The PL18 weight of the TE treatment was significantly higher than that of the control. Fatty acid analysis indicated significantly higher levels of n-3 HUFA, especially eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids, in enriched Artemia (TE). In turn, higher levels of highly unsaturated fatty acids from the n-6 and n-3 series were observed in the TE post-larvae (PL) ,while the PL of the CT showed higher levels of linolenic (18: 3n-3) and stearidonic acid (18: 4n-3). Although at the end of the nursery, no significant differences were detected between survivals, the final weight was significantly higher in TE (TC = 0.896g and TE = 1.082g). The results demonstrate that the supply of n-3 HUFA during the larviculture phase increases the tolerance of F. paulensis post-larvae to salinity and ammonia and still positively affects growth. The weight difference observed at the end of the larviculture phase was maintained throughout the cultivation in the cages. It is recommended, therefore, the supply of n-3 HUFA during larviculture, through the enrichment of Artemia, as a way to produce post-larvae with greater stress tolerance and larger size.