Dietary Inclusion of Tenebrio Molitor Meal in Sea Trout Larvae Rearing: Effects on Fish Growth Performance, Survival, Condition, and GIT and Liver Enzymatic Activity

Abstract

Sea trout (Salmo trutta m. trutta) is a species for which effective methods of rearing are still being developed. They need high-quality protein in their diet, but, considering the ecological consequences of fishmeal production, new sources of protein are needed. Presently, insect meal is one of the most promising alternative sources of protein in the diets of farm animals. Insect production does not result in excessive gas emissions, waste generation or the risk of obtaining low-quality dietary protein. The study on sea trout larvae was carried out for 60 days. Four diets were given to the fish: one control (C), without the inclusion of insect meal, and three experimental, with one unhydrolysed Tenebrio molitor meal (TM) and two hydrolysed Tenebrio molitor meal treatments. The effects of the diets were evaluated on the basis of growth performance (weight and length of the fish, SR, SGR, RGR, FCR and PER), somatic indices (HSI and VSI) and fish condition (CF). We observed that the highest body mass and weight gain were obtained in the control group. However, the lowest mortality and the highest values of RGR were observed only in groups fed diets containing mealworm meal. The results for the hepato- and viscerosomatic indices showed a lack of statistically significant differences between the control group and the unhydrolysed Tenebrio molitor meal group in terms of the enzymatic activities of amylase, lipase and trypsin in the fish intestine and both aminotransferases in the liver. Our study demonstrated that the inclusion of 20% mealworm meal in practical diets for sea trout did not negatively affect growth performance or gastrointestinal tract (GIT) enzyme activity. The hydrolysed mealworm meal and the non-processed mealworm meal had similar effects.

The Effect of Hydrolyzed Insect Meals in Sea Trout Fingerling (Salmo trutta m. trutta) Diets on Growth Performance, Microbiota and Biochemical Blood Parameters

“…To avoid this overestimation, Kp values of 4.76 for the protein content in whole insects and 5.60 for the protein extracts should be used [ 64 ]. The results of the present study are in agreement with the findings of Hoffmann et al [ 37 ], in which no effect on average total length or body mass, SGR, FCR, or PER was observed throughout the experiment. A significant effect of insect meals on survival rate was not observed in either study; however, in the present study, the survival rate was numerically higher and close to 100%.…”

“…morio meal to sea trout diets. The results are characterized by a high survival rate and satisfactory growth performance and feed utilization parameters [ 37 , 59 ]. The positive effect of hydrolyzed fish protein was previously proven by a significant reduction in vertebral anomalies [ 60 ].…”

“…A control diet (CON) and two experimental diets were formulated ( Table 3 ). The control diet was based on previous results described by our research team and literature [ 37 , 39 ]. A 10% hydrolyzed insect meal inclusion was fixed for both the experimental diets.…”

“…In the available literature, data about the use of insect meals in sea trout diets are scarce and they can be found in only one published study described recently by our team [ 37 ]. Moreover, information on the microbiota of this species is very limited.…”

Insect Fat in Animal Nutrition – A Review

“…It should be emphasized that insects as a novel feed ingredient in farm animal diets will be used on a large scale mainly in aquafeeds due to the fact that the legislation process (in the EU) is fastest for both protein and fat (no restrictions) usage. Four forms of insect products are seen in the literature: full-fat insect meals (Nogales Merida et al, 2018;Józefiak et al, 2019a;, defatted meals (Renna et al, 2017), hydrolyzed meals (Hoffmann et al, 2020) and…”