Ontogenia tilapia del Nilo-fisiologia digestiva

Abstract

During the early ontogeny, the transition from endogenous (yolk protein) to exogenous feeding (artifcial diets) represents a critical period linked to the undiferentiated digestive system, with low digestibility of food protein. The objectives of this work were to characterize the morphology of the early Nile tilapia (Oreochromis niloticus) developmental stages and determine the activity of alkaline and acid peptidase enzymes during the ontogenesis from hatching to 20 days post-hatching (DPH). Also, the in vitro efect that exogenous enzymes from Argentine red shrimp (Pleoticus muelleri) waste have on the alkaline peptidases of larvae from 6 to 20 DPH (which correspond to the age at which fsh eat exogenous food) was studied. Both acid and alkaline peptidase activities varied throughout early ontogeny development (from 0.1 to 1, and from 0.1 to 7.1 UE mg protein−1, respectively). The patterns of both enzyme activity variation would be related with changes in endogenous, mixed and exogenous feeding. Our studies show that the additions of the enzyme extract of shrimp have a synergistic efect (from 3 to 6 times) on endogenous in vitro activity. Moreover, the zymogram analysis demonstrates that the bands corresponding to the activity of each species (tilapia and red shrimp) remain active when they are mixed. The increase in peptidase digestive capacity by addition of exogenous enzymes would maximize the assimilation of nutrients from artifcial food during early development.