Stress dominance and metabolic responses of Nile Tilapia

Abstract

It is known that the dominance hierarchy and agonistic behaviors can result in stress to the animals. This behavior influences access, consumption, digestion and metabolism of dietary nutrients. This research aims to quantify the effect of stress on digestive processes, after the establishment of social hierarchy among juvenile Nile tilapia. It will be held at the São Paulo State University, Botucatu, at Nutrition Laboratory of Fish FMVZ. Will be used 80 male fish with initial weight of approximately 60 grams. The fish are fed with feed formulated for the research, with 28% of DP and 3000 kcal / DE / kg diet. Will adopt a completely randomized design with five treatments and four replications in a factorial scheme (2x2), two hierarchies (dominant and submissive), two stimuli (chemical communication and visual communication), and an additional treatment to control (= not submitted or isolated the stimulus and not the hierarchy). Assessments of the effect of stress hierarchy will be measured by means of five studies: a) apparent digestibility of nutrients, b) gastrointestinal transit time, c) haematological parameters, d) morphology of the intestinal epithelium of fish and e) activity digestive enzymes. (AU)