Two formulated diets were evaluated to replace live crab (C) as feed for juveniles Enteroctopus megalocyathus. Formulated diets consisted of crab paste (CP) and a mixture of freeze-dried meals of crab and squid (C&S). After 10 weeks of feeding, the effect of each diet was analysed on productive performance, nutritional and physiological condition and immune system. Both the crab and C&S diets produced the best values for specific growth rate, feed conversion ratio and protein efficiency ratio. The diet C&S proved to be the most digestible with greatest metabolized energy. The CP diet was similar to the C diet in terms of biological value and protein apparent digestibility; nevertheless, its performance was weaker for the other indicators. Furthermore, the highest α-amylase, lipase and alkaline proteolytic activity values were observed in octopuses fed live crab, as opposed to those fed formulated feeds. The type of diet did not affect lysozyme activity in neither mucus nor haemolymph. The production of reactive oxygen species was highest in octopuses fed CP diet. It is proposed the use of C&S diet to study the nutritional requirements and to develop an optimal formulated diet for juvenile Patagonian red octopus.
K E Y W O R D Sdigestibility, digestive enzymes, feed evaluation, freeze-dried ingredients, immune system, metabolized energy