Growth, partial energy balance, mantle and digestive gland lipid composition of Octopus vulgaris (Cuvier, 1797) fed with two artificial diets

Effects of two binders (gelatine and alginate) were tested on growth, survival, partial energy balance and lipid composition of mantle and digestive gland (DG) of Octopus vulgaris. The three diets tested were given as follows: CON, (Loligo gahi) as control, GEL, composed of squid paste (L. gahi) (300 g kg(-1)), fish hydrolyse CPSP (R) (100 g kg(-1)) and fish meal (500 g kg(-1)), agglutinated with 100 g kg(-1) of gelatine and ALG, composed of squid paste (L. gahi) (300 g kg(-1)), fish hydrolyse CPSP (R) (100 g kg(-1)) and fish meal (500 g kg(-1)), all agglutinated with 100 g kg(-1) of alginate. Growth rates were 13.7 +/- 2.1, 2.1 +/- 2.8 and) -2.4 +/- 2.9 g kg(-1) bw day(-1), for octopuses fed CON, GEL and ALG diets, respectively. DGs of octopuses had higher concentrations of fatty acids (FA) than the mantle. DG of animals fed CON had higher concentrations of FAs than those fed the artificial diets. Energetic balance demonstrated that physiologically useful energy for maintenance E(B) was affected by type of diet, with negative values of E(B) in animals fed ALG and positive (85 and 154 kJ kg(-1) day(-1)) in octopuses fed GEL and CON, respectively. The ALG diet did not cope with the physiological requirements for octopus growth.