Atrato-palatabilidade para juvenis de tilápia do Nilo (Oreochromis niloticus)

Abstract

The present study was performed with the aim of determining the compelling palatability for Nile tilapia juveniles fed with diets containing dry and liquid protein hydrolysates and inclusion levels of the flavoring Atractus Aqva® in replacement of fishmeal. In order to determine the fish’s behavior concerning dry hydrolysates, four Nile tilapia juveniles (2.90 ± 0.01 g) were used, distributed in 10L tanks. Four experimental diets containing 5% inclusion of poultry protein hydrolysate (PHF), swine liver protein hydrolysate (PHS), feather protein hydrolysate (PHP) and the fishmeal (FPE, control treatment) were elaborated. The animals were adapted to the experimental conditions for fifteen days before the experiments. The experiment lasted for eight days, and fish were fed four times a day with a supply of 20 pellets per animal. Regarding the evaluation of the feeding behaviors of fish fed with diets containing Atractus Aqva®, five juvenile fish (2.58 ± 0.27 g) were distributed in 10L tanks, and five experimental diets were made with 0.25% (A25); 0.50% (A50); and 0.75% (A75) of flavoring inclusion, besides the positive control with fishmeal (FPE) and the negative control without fishmeal (SPE). The animals were adapted to the experimental conditions for eight days, and were fed four times a day, with 30 pellets being offered per feeding event. The experiment lasted for eight days. In order to determine the feeding behavior of fish concerning the liquid hydrolysates, five Nile tilapia juveniles (2.51 ± 0.13 g) were also distributed in 10L tanks. The following diets were elaborated: a diet containing a 5% inclusion level of fishmeal (FPE); liquid protein hydrolysate of porcine mucosa (PHM), poultry (PHF), fish oil (OPE) and a diet without fishmeal (SPE). The animals were also adapted to the experimental conditions, for ten days, and were fed five times a day, which in each feeding event 20 pellets were supplied per fish. This experiment lasted for twelve days. In both essays, the experimental design was completely randomized and the feeding behaviors regarding time to capture first pellet, number of pellet rejections, number of approximations without capturing the pellet and number of consumed pellets were observed in each feeding by means of three-minute footages made with a digital camera. The obtained data were submitted to a parametric variance analysis (ANOVA) and in case of significant effect, the multiple comparison test of Tukey was performed at a 5% significance level. Regarding the dry hydrolysates, PHF has positively influenced feed consumption and pellets rejection after capture (P < 0.05) in comparison to PHP, not differing from the other diets (P > 0.05). The diet PHF provided the highest palatability index (10.82%), representing a 17% increase in final feed consumption and a 6.89 times lower rejections in relation to FPE. Concerning the inclusion levels of the flavoring, A75 presented significant differences (P < 0.05) on the number of approximations without capturing the pellet and a high palatability index of 10.49%, besides a 13% increase in the final feed consumption, a 23.13% lower pellets rejection and a 3.3 times higher approximations without capturing pellets in relation to FPE. Regarding liquid hydrolysates, none of the observed parameters were statistically different (P > 0.05), and all diets presented negative palatability indexes in comparison to FPE. The SPE diet had a palatability index of -2.34%, OPE -6.84%, PHM -10.80%, and PHF a -15.21% index. Both PHF and PHM reduced the pellet consumption in comparison to FPE in approximately 28% and 20%, respectively. Thus, based on the obtained results the replacement of fishmeal in Nile tilapia juvenile diets can be achieved using both dry PHF and A75, whilst using liquid hydrolysates is not recommended, as they did not present good compelling palatability results.