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

Abstract

The effects of two binders (gelatine and alginate), were tested on growth, survival, partial energy balance and lipid composition of the mantle and digestive gland of O. vulgaris . Thirty animals were individually placed in 30 cylindrical tanks of 80 L in water volume each. Octopus average weight was of 713.0±127.9 g at the start of the experiment. Octopuses were fed with 10% (wet weight of food/wet weight of the animal) (% bw d -1 ) once a day at 09:00 h. The three diets were tested (10 octopuses per diet: 1) squid ( Loligo gahi ) as a control diet, 2) GEL, composed of squid paste ( Loligo gahi ) (30%), fish hydrolyse CPSP ® (10%), and high quality fish flower (50%), agglutinated with 10% of gelatine and 3) ALG, composed of squid paste ( Loligo gahi ) (30%), fish hydrolyse CPSP ® (10%), and high quality fish flower (50%), all agglutinated with 10% of alginate. Water temperature was of 15±1 ºC and a natural photoperiod during February and March 2008 was used. Growth rates were of 1.4±0.2, 0.2±0.2 and - 0.2±0.2 % Bw d -1 , for octopuses fed the control, GEL and ALG diets, respectively, and were higher (p<0.05) for the control, compared to the two artificial diets (p=0.0001) while the GEL diet promoted higher growth (p=0.003) compared to the ALG diet. None of the artificial diets tested promoted significant growth at the end of the experiment.