Tenebrio MolitorMeal in Rainbow Trout (Oncorhynchus Mykiss) Diets: Effects on Animal Performance, Nutrient Digestibility and Chemical Composition of Fillets

Abstract

This study evaluated the effects of diets containing Tenebrio molitor (TM) larvae meal on growth performances, somatic indexes, nutrient digestibility, dorsal muscle proximate and fatty acid (FA) compositions of rainbow trout. Three hundred sixty fish were randomly divided into three groups with four replicates each. The groups were fed diets differing in TM inclusion: 0% (TM0), 25% (TM25) and 50% (TM50) as fed weight basis. Weight gain was not affected by treatment. Feeding rate was significantly higher in TM0 than TM50. Feed conversion ratio was significantly higher in TM0 than TM25 and TM50, while an opposite trend was observed for protein efficiency ratio and specific growth rate. The survival rate was significantly lower in TM0 than TM25 and TM50. The apparent digestibility of protein was significantly lower in the TM50 group than the other groups, while the apparent digestibility of dry matter, organic matter and lipids was unaffected by treatment. If compared to control, the protein and lipid contents of fillets were respectively increased and decreased following TM inclusion in the diet. The Σn3/Σn6 FA ratio of fish dorsal muscle was linearly (TM0>TM25>TM50) reduced by TM inclusion in the diet. Results suggested that TM could be used during the growing phase in trout farming; however, additional studies on specific feeding strategies and diet formulations are needed to limit its negative effects on the lipid fraction of fillets.

Effect of Tenebrio molitor larvae meal on growth performance, in vivo nutrients digestibility, somatic and marketable indexes of gilthead sea bream (Sparus aurata)

“…The lower crude protein digestibility in TM50 diet can reflect the higher chitin content of the diet leading to a higher chitin-linked protein quota (Bellucco et al, 2013). The same effect was observed by Belforti et al (2015) which reported a decrease in crude protein digestibility in fish fed diet containing an inclusion of 50% of TM without effects on weight gain.…”

“…Ng et al (2001), replacing 40 and 80% of fishmeal with mealworm in African catfish (Clarias gariepinus), observed similar growth performance and feed intake to the control group, suggesting a high palatability for this kind of insect meal by the considered species of fish. In a more recent paper, Belforti et al (2015) reported that the inclusion of 25 or 50% of TM in rainbow trout diets did not affect the final fish weight and weight gain, but significantly ameliorated performances parameters as FCR, SGR and PER.…”

The environmental sustainability of insects as food and feed. A review

“…However, replacing 70% of the fish meal did depress growth. A similar trial conducted with rainbow trout (Oncorhynchus mykiss) found that weight gain was not affected at higher inclusion levels of mealworm meal, while the protein content increased and lipid contents of fillets decreased, compared to the control (Belforti et al 2015). A complete replacement of fish meal by yellow mealworm meal increased the fat content of Pacific white shrimp, but did not affect its growth or feed conversion (Panini et al 2017).…”

Sustainable farming of the mealworm Tenebrio molitor for the production of food and feed

“…The low calcium levels in mealworms can be avoided by feeding the larvae on calcium-enriched diets [33,34]. Furthermore, mealworms have been tested in various aquaculture settings and up to 25% of the traditional feed can be replaced without compromising the yields achieved on the standard diet, whereas higher proportions of mealworm had a negative effect [27,[35][36][37]. For shrimp farming, the complete replacement of fish meal with mealworms resulted in an increase in body weight and lipid content [38].…”