Effects of faba beans (Vicia faba L.) on growth performance, textural quality and physiological indices of tilapia (Oreochromis niloticus)

Tilapia (Oreochromis niloticus) is a fish species farmed in freshwater aquaculture worldwide, for which increased intensification has caused many problems including poor muscle quality. The tilapia fed faba beans (Vicia faba L.) had improved fish crispiness and firmness, but faba beans contain a variety of antinutritional factors which potentially interfere with certain growth performance and physiological indices. There little is known about the growth performance, and physiological indices of tilapia fed with different amounts of dietary faba bean. This study was conducted to evaluate the effects of faba bean on growth performance, histological analysis, physiological indices and related gene expression profiles in tilapia (initial mean body weight of 463.86 ± 16.51 g). A basal diet (diet 1) containing no faba beans was fed to a control group and four other diets were produced by inclusion of 40%, 50%, 60% and 70% faba beans as diet 2, 3, 4, and 5, respectively. The results showed that there was no significant effect of dietary faba bean on the survival rate of tilapia. A reduction in the body weight, weight gain rate (WGR) and specific growth rate (SGR) were observed for tilapia fed diets 2, 3, 4 and 5 compared with the control. In the trial groups fed diets 2, 3, 4 and 5, a significant increase in the liver somatic index (LSI) and viscerosomatic index (VSI) was observed compared to those fed the control diet at 90 days (P < 0.05). Tilapia fed faba beans had higher muscle fiber density, wider spaces between muscle fibers and smaller fiber diameter and area, with the most difference in tilapia fed diet 4. The glutathione peroxidase (GSH-Px) was significantly decreased compared with the control group in both serum and liver (P < 0.05), while superoxide dismutase (SOD) was not significantly different. Compared with the control group, glucose 6-phosphate dehydrogenase (G6PD) activities of dietary faba bean groups were significantly decreased (P < 0.05). The aspartate transaminase (AST) and alanine aminotransferase (ALT) were significantly increased by dietary faba bean. Dietary faba bean did not affect acid phosphatase (ACP) and alkaline phosphatase (AKP). In summary, dietary faba bean at an optimum level of 60%, improved muscle fibers but had negative effects on growth performance and physiological parameters in the tilapia. The results would contribute to an understanding of the growth, textural quality, and physiological parameters affecting the tilapia crisping process.