Apparent digestibility coefficient and metabolizable energy of feed ingredients for the sea bream Archosargus rhomboidafis (L. 1758, Pisces: Sparidae)

Abstract

 The digestibility coefficient was determined for 13 meals of animal and vegetal origin used as ingredients in feed of the sea bream Archosargus rhomboidalis. The specimens were acclimatized in 1000-L tanks for 10 days, receiving separately the reference feed and the 13 experimental diets composed of 69.3% of the reference mixture, 1% of the indicator and 29.7% of the meals under study. Subsequently, 12 specimens were placed per aquarium and fed for 5 days with the 14 treatments with 3 replicas each. The feces were collected daily by decantation and then separated by water filtration of the aquariums, thus obtaining the fecal material in order to determine the digestibility coefficient of each treatment and of each ingredient. The digestibility coefficients of the dry matter, protein, lipids and energy of the different treatments indicate that the meals of animal origin were better digested than those of vegetal origin; also, the nutritional assimilation of the latter depends on the type of carbohydrates they contain, as well as on the ash content. High concentrations of crude fiber should be limited in the diets due to their low nutritional value and because they harm the quality of the water. The crude fiber content is inversely related to the digestibility of the dry matter, protein and energy. The soluble carbohydrates are a good source of nutritional sugar for the sea bream. The maximum average values of temperature, salinity and dissolved oxygen were registered.