Effects of supplemented anti-nutritive substances from rapeseed on growth and health performance of rainbow trout (Oncorhynchus mykiss)

Inclusion of certain plant protein products in fish feed is limited by multiple anti-nutritive factors (ANF) present in plants. Since these factors negatively affect growth performance and health of fish, the aim of this study was to investigate if a specific factor could be primarily responsible for reduced growth and health. Eight identical basal diets including rapeseed protein concentrate were supplemented with five tiered levels of phytic acid (PA) or three tiered levels of glucosinolates (GLS) respectively. One basal rapeseed diet served as control. Diets were fed twice per day to apparent satiation to triplicate groups of juvenile rainbow trout (Oncorhynchus mykiss). After 38 and 56 days of feeding, growth performance as well as health parameters were analysed for diets containing glucosinolates (38 feeding days) and phytic acid (56 feeding days), respectively. Performance and health parameters were determined for control group at both sampling times. Dietary phytic acid showed significant effects on growth performance and whole body composition. Lowest concentration of supplemented phytic acid (1.0%) significantly improved overall growth performance while higher inclusion percentages significantly decreased voluntary feed intake and subsequently growth performance. Supplementation with glucosinolates had no significant effect on any of the investigated parameters.

Automated summary

This study found that dietary phytic acid significantly affects the growth performance and whole body composition of fish. Supplementing lower concentrations of phytic acid can significantly improve growth performance, but higher concentrations can reduce voluntary feed intake and subsequently growth performance. In contrast, supplementation with glucosinolates had no significant effect on these parameters.