Efeito de doses de excrementos de aves na produção e qualidade nutricional de Lemna valdiviana Phil (Araceae) para piscicultura

Abstract

The duckweeds are aquatic plants with high reproduction capacity and high nutritional value. For this reason, have great potential for usage as raw material for the production of feed for fish. Its production and nutritional quality are directly related to the nutrients wealth of the water where they grown up. The purpose of this study was to evaluate the production and nutritional quality of Lemna valdiviana Phil depending on the doses of poultry excrement in water applied to crops for the production of feed for fish farming. The experiment was conducted in a completely randomized designed with 4 treatments and 3 repetitions. The treatments were: T1 - 0 g/m3; T2 - 150 g/m3, T3 - 300 g/m3 and T4 - 450 g/m3 of fresh bird excrement, distributed in a single dose per unit of water surface, in which is cultivated L. valdiviana. The following variables were analyzed in the water during the experiment: Total Alkalinity (AT), N-nitrite (NO2-N), N-nitrate (NO3-N), N-ammonia (NH3-N), N-total (NT), orthophosphate (P-PO4-3) and total phosphorus (PT) to 1st , 7th , 14th and 21st days of the experiment, as well as pH and temperature recorded daily. In plant production were analyzed the dry biomass, content of crude protein, total fat, crude fiber, ash, moisture and nutrients in dry mass. The largest production of L. valdiviana was obtained with the treatment which contained a dose of 450 g/m3 excrement of birds, this being the one which determined their best nutritional quality, providing higher levels of protein and some mineral nutrients such as P, N, Na and Ca in dry mass.