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FCR Analysis: Mealworm x Trout

In an overview by Makkar et al. (2014), it was indicated that replacing fishmeal with insect meal in various animal feed did not show any adverse effects on livestock performance and health.

With fishmeal posing a series of environmental challenges to the aquaculture industry, intensive research & development have been conducted with alternative protein sources. A feed trial, in particular, was undertaken at Sparos aquaculture facility in Portugal where it evaluated the efficacy of mealworms with respect to growth, body composition and apparent digestibility of nutrients.


Feed Trial Parameters

Rainbow trout fingerlings of ~5g were monitored over the course of 90days with bodyweight and FCR readings taken on day 28, 60 and 90. Substituting fishmeal with mealworms at various amounts, the feed trial consists of 5 diets: Control, TM20 (20% replacement), TM30 (30% replacement), TM60 (60% replacement), TM100 (100% replacement).


Results were as follows:


DAY 28

DAY 60

DAY 90

At the end of the feed trial, livestock in TM100 weighs an average of 30% more than control with an 18% lower FCR. The results are clear that the inclusion of mealworms in the aquaculture diet has significant benefits pertaining to the trout’s growth rate and FCR with no detrimental effect on palatability. For aquaculture, this ultimately translates to lower feed cost and higher livestock turnover.


In another feed trial, mealworms were found to be an acceptable protein source for African catfish. Substituting up to 80% of fish meal with mealworms in isoproteic diets resulted in growth performance and higher feed utilization efficiency as mealworms were found to be highly palatable. Fish fed with live/dried mealworms in the morning and commercial aquafeed in the afternoon grew equally well or better than fish fed solely on commercial aquafeed. Catfish with mealworm-based diets were also found to have significantly more lipids in their carcass.


Apart from rainbow trout, mealworm has also proven to be beneficial for the European Seabass and Gilthead Seabream. With great potential for mealworms to be included in aquafeed, the possibilities are endless. Interested in a feed trial or have a target species in mind? Let us know!