High protein Tenebrio molitor larvae meal in rainbow trout diets
Christian Caimi1, Ilaria Biasato1, Giulia Chemello1, Achille Schiavone2,3, Marco Meneguz1, Sihem
Dabbou2, Manuela Renna2, Francesco Gai3, Laura Gasco1
1Dipartimento di Scienze Agrarie, Forestali e Alimentari, University of Torino, Italy. 2Dipartimento di Scienze Veterinarie, University of Torino, Italy.
3Istituto di Scienze delle Produzioni Alimentari, Consiglio Nazionale delle Ricerche, Italy.
Contact: christian.caimi@unito.it
In recent years, there has been a growing interest towards the use of insect protein meals in aquaculture feeds. The use of this alternative raw material has been successfully tested in different fish species, such as Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), seabream (Sparus aurata), and seabass (Dicentrarchus labrax). The aim of this study was to evaluate the substitution of fishmeal with a high protein Tenebrio molitor larvae meal (TM) in rainbow trout diets. At the beginning of the trial, 252 fish were randomly divided into 12 fiberglass tanks (3 replicates/diet). Four experimental diets were formulated to be isonitrogenous and isoenergetic: TM0 (without TM), and TM5, TM10 and TM20 (with 5, 10, and 20% of TM inclusion level, respectively) in substitution of 25, 50 and 100% of fishmeal. At the end of trial (154 days), the following performance indexes were calculated: survival, individual weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio. Fifteen fish per treatment were killed by over anaesthesia and individually weighed. Fish length was measured to calculate the Fulton's condition factor (K). The fish were dissected to determine the carcass yield (CY), hepatosomatic index (HSI), viscerosomatic index (VSI), and the coefficient of fatness (CF). An in
vivo digestibility trial was also contemporarily performed to determine the apparent digestibility
coefficients (ADC) of dry matter, crude protein and ether extract of the diets. One hundred and eighty trout (15 fish/tank/tank) were divided into 12 cylindroconical tanks (3 replicates/diet). The fish were fed twice a day with the same diets used in the growth trial. The faeces were collected daily from each tank for 4 consecutive weeks, using a Choubert’ system. The faeces were freeze dried and frozen (-20°C) until analysed. All data were statistically analysed by IBM SPSS Statistics V20.0.0 software (P value < 0.05). No differences between treatments were observed for the performance indexes. No differences were highlighted for K, CY, VSI, and CF, but HSI resulted higher in the fish fed TM20 compared to those fed TM0. About the digestibility, all the ADC values results higher than 93%. Differences were recorded for all the ADC parameters. TM5 diet showed the highest values. The obtained results confirm the high potential of the inclusion of Tenebrio
molitor larvae meal in rainbow trout feed.
Acknowledgements
The research was partially supported by AGER project “Fine Feed for Fish (4F)”, Rif.nr. 2016-01-01. 1 2 3 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
