Palatability of Protein Hydrolysates from Industrial Byproducts for Nile Tilapia Juveniles

This study was performed with the aim of determining the palatability of diets containing poultry and swine protein hydrolysates for Nile tilapia. Five experimental diets were made with a 5% inclusion level of fishmeal (FPE), poultry protein hydrolysate (PHF), liquid swine hydrolysate (PHS), feather protein hydrolysate (PHP), and swine mucosa hydrolysate (PHM). Five juveniles (2.81 ± 0.17 g) were placed in 10 L aquariums and fed five times a day after a raffle of offered diets. In each feeding throughout the day, 30 pellets were offered per fish. The experimental design was completely randomized, with five replicates per day. A three-minute footage period was established for each feeding with a digital camera. The following feeding behaviors were observed: time to capture the first pellet, number of pellet rejections, number of approaches without capturing the pellet, and number of consumed pellets. No observed parameters presented significant differences (p > 0.05). PHF provided a palatability index of 12.27%, while PHM had an index of 9.33%, PHF of 8.77%, and PHP of 7.74%. Both diets PHS and PHM increased the final consumption of pellets in comparison to FPE by more than 10%, despite the absence of a significant effect.