Mealworm meal use in sea trout (Salmo trutta m. trutta, L.) fingerling diets: effects on growth performance, histomorphology of the gastrointestinal tract and blood parameters

Insect meals are a group of promising feed materials and sources of nutrients. Their production does not entail deforestation, global warming, environmental pollution or decreased biodiversity. One of the most important farmed insect species is mealworm, which is allowed to be used in aquafeeds by the European Commission Regulation no. 2017/893. The aim of this study was to examine four doses of mealworm meal (TM10 = 10%, TM20 = 20%, TM30 = 30% and TM40 = 40%) in sea trout (Salmo trutta m. trutta) fingerling diets and their effects on growth performance, somatic and condition indices, blood parameters, histomorphological characteristics and body composition. Our results showed the most satisfactory growth performance results with 10% mealworm meal. The feed conversion ratio (FCR), protein efficiency ratio (PER), relative growth rate (RGR) and specific growth rate (SGR) was similar in the control and TM10 group. The lowest fish survival (95%) was occurred in the group of fish fed TM40, and the highest (98.33%) in fish fed control or TM10 diets. The fish condition and the hepatosomatic index were similar among treatments. The histomorphological structures of the intestine and liver were not negatively affected by the experimental diets. The inclusion of up to 40% mealworm meal did not negatively affect growth performance, feed utilization, fish health or survival.

Automated summary

Insect meals, specifically mealworms, are a promising and sustainable source of nutrients for aquafeeds. The study found that using 10% mealworm meal in sea trout fingerling diets resulted in the most satisfactory growth performance. Higher doses of mealworm meal did not negatively impact growth performance, feed utilization, fish health, or survival rates.