Evaluation of commercial and natural food in experimental cultures of white shrimp based on stable carbon isotopes

The farming of shrimp is developing quickly worldwide, and recently, ingredients such as seaweeds in low proportion (25 to 4 %), incorporated into the commercial food, have been shown to improve the shrimp productive variables. The change of commercial foods to commercial feed with a proportion of natural food, and finally, to natural food has been little and simultaneously evaluated. The aim of our study was to determine the relative contribution of dietary carbon to the growth of Litopenaeus vannamei fed with a proportion of 4 % Sargassum (delta C-13 = -20.9 +/- 0.05 aEuro degrees), 4 % Ulva (delta C-13 = -20.6 +/- 0.6 aEuro degrees) meal, and a control diet (delta C-13 = -22.6 +/- 0.2 aEuro degrees) in 60-L tanks for 30 days, and finally, with the green seaweed Ulva spp. (delta C-13 = -13.2 +/- 0.25 aEuro degrees) and Ulva meal (delta C-13 = -14.5 +/- 0.6 aEuro degrees) in open-air ponds for 120 days, by measuring delta C-13 for each of the foods and in the muscle of shrimp. After 15 days, the rates of metabolic turnover (Delta C-13 = delta C-13(shrimp) - delta C-13(food)) were constant until the end of the experiment in the tanks. The muscle of shrimp assimilated carbon from all diets, which demonstrated the potential use of combined diets and the optimization of their use in diets containing seaweed. Our data will be useful in future interpretations of field and laboratory isotopic values for this species.