Aquaculture Reports (Dec 2024)
Complete replacement of fishmeal with unconventional animal protein sources: A comparative study of the effects of use of mealworm, earthworm and zooplankton on growth parameters, fatty acid composition and sensory profile rainbow trout
Abstract
The global trend in aquaculture is to replace fishmeal with an alternative and sustainable source of protein for fish farming. As a result, some species of invertebrates have found a place in aquaculture as a rich source of protein and a promising substitute for fishmeal. This study aimed to investigate the effects of alternative protein sources on the growth parameters of rainbow trout (Oncorhynchus mykiss) as well as the fatty acid profile and the sensory quality of the fish fillets. The gas chromatography technique with a flame ionization detector was used to determine the fatty acid composition of the rainbow trout fillets, while different equations were used to determine the growth parameters and the hepatosomatic index. The sensory evaluation of the rainbow trout fillet was determined by a descriptive sensory analysis, a quality assessment and a consumer acceptance test. The replacement of fishmeal by mealworms (MWD) and earthworms (EWD) resulted in a positive effect on growth parameters, feed conversion, and hepatosomatic index (HSI) values. The mortallity of the rainbow trout fed with the experimental diets was less than 28 %. The eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content of the trout fillets decreased with the inclusion of MWD (1.34 and 5.20 %, respectively) and EWD (1.74 and 6.41 %, respectively) in the trout diet. Feeding rainbow trout with MWD and EWD caused a decrease in the n-3/n-6 ratio compared to FMD (0.32 and 0.34, respectively vs. 0.56), whereas the addition of ZOD resulted in the increase of the n-3/n-6 ratio (0.67). The samples of fillets of trout fed with MWD and EWD belonged to the ''very good'' level of average sensory quality, while the fillets of trout fed with zooplankton were in the ''good'' quality range. Regarding acceptability by consumers all rainbow trout fillets shown good consumer acceptance.
