Resumo

PARDO-CARRASCO, Sandra; BRU-CORDERO, Samir  e  GARCIA-GONZALES, José J. Can protein content be reduced in fish meal used in periphyton-based polyculture?. Orinoquia [online]. 2014, vol.18, n.1, pp.35-42. ISSN 0121-3709.

In order to evaluate the effects of periphyton on the performance of the polyculture of Nile tilapia (Oreochromis niloticus) and Bocachico (Prochilodus magdalenae) conducted an experimental cultivation for 8 months. Twelve 90m² ponds were used in semi-intensive Cultivation conditions, at low stocking density (2.6 tilapia/ m², 0.7 bocachico/m²). The ponds were not fertilised during the experimental period. Black 1.2 m long and 6 cm diameter plastic tubes were installed vertically, using 3.3 tubes/m² spacing (B1=presence, B2=absence) as substrate for the periphyton. Two feeding strategies were tested; A1 involved fish meal containing 20% protein throughout the all time and A2 a commercial fish-meal plan having decreasing protein levels (38%, 32% and 24%). A completely randomised factorial design was used, having three repetitions per treatment. Survival (%), net productivity (kg/ha) and feed conversion ratio (FCR) were evaluated with ANOVA, using a general linear model (GLM); weight (g) was analysed using ANOVA with a model comparing means in which time appeared as the third factor (monthly sampling). No interaction was found between the factors studied here (AxB, p<0.05) regarding net productivity (kg/ha) or FCR for either specie. Factor A had the main effect on tilapia survival, but not on other parameters measured here. There was an interaction between factor B and time regarding bocachico weight. Bocachico cultured with substrate for periphyton gained most weight during month 8; this was important because it could lead to reducing protein content in the diet, thereby reducing costs and sources of contamination. These results were possibly due to the presence of periphyton in the ponds. The foregoing has highlighted a strategy for reducing the demand for high protein content fish meal by a periphyton-based system for fish culture.

Palavras-chave : periphyton; tilapia; bocachico.

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