Attractiveness and palatability of feather protein hydrolysate for juvenile Nile tilapia (Oreochromis niloticus)

Abstract

The objective of the study was to determine the attractiveness and palatability of feather hydrolysate for juvenile Nile tilapia. Twelve Nile tilapia (Oreochromis niloticus) fingerlings with an average weight of 9.63 ± 0.9 g were used, distributed in 12 aquariums with a useful volume of 20 liters. Six diets were formulated, as follows: T0: Control, T1: 1% feather hydrolysate, T2: 2% feather hydrolysate, T3: 3% feather hydrolysate, T4: 4% feather hydrolysate and T5: 5% feather hydrolysate. The fish went through an adaptation period to record their feeding behavior in which they were fed twice a day, for six days, with 20 pellets per aquarium. The experimental design used was completely randomized. To assess attractiveness and palatability, the following eating behaviors were observed: time taken to capture the first pellet (seconds), number of rejections after capture, number of approaches without capture and number of pellets consumed. These values were used to calculate the attractiveness and palatability index. Data were submitted to parametric analysis of variance (ANOVA), and Tukey's multiple comparison test was also performed, with a significance level of 5%. All diets containing the hydrolysate showed a positive palatability index when compared to the control treatment. Treatment T3 had the best palatability index of 6.66%, followed by T2 4.66%, T5 4.30%, T1 3.92% and T4 0.20%. Feather protein hydrolysate can be used to replace fish meal in diets for Nile tilapia, without altering palatability and feeding behavior.