Desempenho zootécnico e parâmetros somáticos de carpa comum (Cyprinus carpio) alimentada com Azolla Caroliniana

Abstract

Aquatic plants form part of the limnic system of lakes and rivers. Azolla caroliniana aquatic macrophyte can be included in fish diets, as it is a source of nutrients (proteins, amino acids, minerals, lipids, cell wall fractions and polyphenols) and can act as a food supplement. The composition of aquatic macrophytes may have a significant amount of fiber, so their centesimal composition must be evaluated to ensure an adequate level of inclusion and not bring harm to animals. Therefore, the aim of this study was to evaluate two levels of A. caroliniana inclusion in common carp (Cyprinus carpio) diets by evaluating zootechnical performance parameters and somatic indices in fish. The experimental design was completely randomized with three treatments and three replications each. The following experimental diets represented the treatments: CONT = no addition of A. caroliniana; AZ5 = 5% addition of A. caroliniana; AZ10 = 10% addition of A. caroliniana. We used 72 juveniles of common carp (Cyprinus carpio) distributed in 9 0.277 m3 net cages. The fish were fed the experimental diets for five weeks, receiving 3% of the total tank biomass, divided into two daily feeds (9 and 16 hours). The amount of food was adjusted by biweekly biometrics. At the end of the experimental period, juveniles did not show any changes between treatments regarding final weight, final total length, condition factor and apparent feed conversion. However, the average daily gain, relative weight gain and specific growth rate were significantly lower in fish that received 10% A. caroliniana in the diet. Regarding the somatic indices, no significant differences were observed between treatments for any of the evaluated parameters. Thus, due to the high content of insoluble fiber present in this macrophyte, it is recommended that it be included in a maximum of 5% of the common carp diet so as not to impair animal performance.