Uso das proteases do látex de Calotropis procera em dietas para tilápia do Nilo (Oreochromis niloticus): Desempenho zootécnico, digestibilidade e parâmetros hematológicos

Abstract

Among the productive costs involved in aquaculture, artificial feeding is the most expressive, justifying the performance of several studies prioritizing the appropriate balance of rations that increases productivity and reduces environmental impact. The use of enzymes is a promising strategy to maximize the efficiency of the use of diets, because they reduce the costs of production while maintaining the performance of the animals, as they improve the digestibility and reduce antinutritional factors. The objective of this work was to evaluate the effect of the inclusion of different concentrations of Calotropis procera latex (LP) proteases on Nile tilapia rations by means of zootechnical performance, hematological parameters, digestibility, centesimal composition of fillets and rations, and water quality parameters. The experiment lasted 60 days with the use of 160 fingerlings with initial weight of 3.10 ± 0.55 g, distributed in 16 aquariums, fed rations with three levels of inclusion (LP) (100, 200, 300 mg kg-1) respectively (Lp-Cp 01; Lp-Cp 02; Lp-Cp 03) and a control (without LP). The experiments were performed with four replicates each and the animals were fed three times a day (8, 12, and 16 hours), ranging from 10 to 5% of their biomass. The obtained data were submitted to ANOVA, with the multiple comparison test of Tukey averages (p <0.05). Among the parameters of water quality, the reactive phosphorus was the only parameter that reached values above the recommended, the other parameters were stable and within the limits recommended for the species. For zootechnical performance, no significant difference (p˃0.05) was observed between the treatments. However, there was a trend of improvement in weight gain (GP), daily weight gain (GPD), apparent feed conversion (CAA), final biomass (BF) and protein efficiency index (IEP) in treatments with (LP), (Lp-Cp 03), which presented a significant difference (p <0.05) for specific growth rate (TCE) and feed efficiency (AE) in relation to the control. The apparent digestibility coefficients (CDA) of crude protein, dry matter and lipids, as well as body composition parameters did not present significant differences between treatments (p˃0.05). Hematological parameters did not show a significant difference between treatments (p˃0.05). The inclusion levels of the (LP) proteases under the conditions evaluated did not improve the digestibility of the diets, however, there was no compromise of the productive and hematological performance of the animals and could be considered a promising alternative, through additional studies.