Protein levels for Litopenaeus vannamei in semi-intensive and biofloc systems

•We performed a comparison between two culture systems, semi-intensive and biofloc.•We observed different protein requirements of different systems.•Part of the experiment was conducted on a grand scale.•Production cost was estimated in both culture systems.

The aims of this research were to evaluate the zootechnical performance and dietary cost for the marine shrimp (Litopenaeus vannamei) cultured in a superintensive biofloc system and a conventional semi-intensive system using diets containing different protein levels. Four different diets, with crude protein (CP) contents of 24.3, 30.3, 32.9 and 36.7% were produced. In the laboratory, experimental culture in the biofloc system was performed in twelve experimental units at a density of 250 shrimp m− 3, the four treatments were performed in triplicate. The semi-intensive culture system was applied at the commercial farm in eleven ponds containing 15.5 shrimp m− 2. After 49 days, the zootechnical performance of the shrimp was rated, and the cost per kilogram of shrimp was produced by both culture systems. In the semi-intensive system, the shrimp fed with a diet containing 32.9% CP showed a higher final weight and weight gain and a lower dietary cost. In the biofloc culture, a higher final weight, weight gain, growth rate and productivity were observed in shrimp fed diets containing 30.3, 32.9 and 36.7% CP compared with those fed a diet containing 24.3% CP. The lowest dietary cost of shrimp farming in the biofloc system was registered in the shrimp fed the 30.3% CP diet, whereas, in the semi-intensive system, the highest final weight, highest weight gain and lowest cost were observed in shrimp fed the 32.9% CP diet.