Desempenho zootécnico e expressão dos genes miogênicos de pós-larva de Colossoma macropomum alimentados com náuplios de artêmia.

Abstract

Colossoma macropomum, tambaqui, is the species with the highest production in Brazil among native fish. In larviculture, Artemia nauplii are commonly used due to their high protein, energy and free amino acid value that facilitate digestion by post-larvae. However, as it is a high-cost input, it is necessary to avoid waste in larviculture. Thus, the objective of the present study was to determine the ideal amount of Artemia nauplii per C. macropomum larvae through the analysis of zootechnical performance and expression of myogenic genes: myoblast-determining factor (myod), myogenin (myog) and myostatin (mstn). For this, tambaqui larvae, aged six days after hatching (DAE) were cultivated in a recirculating aquaculture system (RAS) in 15 plastic tanks of 60 L, at a density of 10 post-larvae/L, for 14 days. Five densities of Artemia nauplii (AN) (100, 250, 500, 750 and 1000 AN/post-larva) were tested in three replications. Water quality parameters were analyzed daily. On the 6th, 13th and 20th DAE, the following were evaluated: total length, weight, daily weight gain (mg.Day-1), specific growth rate (%.day-1) and survival (%). And at 20th DAE, 9 larvae were collected for gene expression analysis. After 14 experimental days, the mean value of dissolved oxygen showed a significant decrease with increasing live food density, but with no effect on survival between the treatments tested. In the first week, larvae fed with less than 500 AN/post-larvae had significantly lower growth and in the second week, larvae fed with 1000 AN/post-larva had the highest weight and total length (p < 0.05). Relative expression levels of myogenic genes were significantly higher in larvae fed with 100, 250 and 500 AN/post-larvae. Based on the analysis of segmented and linear regression on weight, respectively, in the first week the ideal amount calculated was 411 AN/post-larvae and in the second week it was 1000 AN/post-larvae. Thus, different AN density influenced the zootechnical performance, water quality and the expression of myogenic genes in the post-larvae of C. macropomum. More studies on different genes and stages of larval development are needed to associate the effect of live food with the zootechnical performance of C. macropomum post-larvae.