Effect of fatty acid-enriched black soldier fly larvae meal combined with chitinase on the metabolic processes of Nile tilapia

Abstract

The aim of this study is to determine to what extent the addition of chitinase to black soldier fly (BSF) larval meal enriched or not with long-chain polyunsaturated fatty acids (LC-PUFAs) could improve growth, protein digestion processes and gut microbial composition in Nile tilapia. Two different types of BSF meal were produced, in which larvae were reared on substrates formulated with vegetable ingredients (VGS) or marine fish offal (FOS). The BSF raised on VGS was enriched in α-linolenic acid-ALA while that raised on FOS was enriched in ALA + eicosapentaenoic acid-EPA +docosahexaenoic-acid-DHA. Six BSF-based diets, enriched or not with chitinase, were formulated and compared with a control diet based on fishmeal and fish oil (FMFO). Two doses (D) of chitinase from Aspergillus niger (2 g and 5 g/kg feed) were added to the BSF larval diets (VGD0 and FOD0) to obtain four additional diets: VGD2, VGD5, FOD2 and FOD5. After 53 days of feeding, results showed that the BSF/FOS based diets induced feed utilization, protein efficiency and digestibility, as well as growth comparable to the FMFO control diet, but better than the BSF/VGS based diets. The supplementation of chitinase to BSF/FOS increased in fish intestine the relative abundance of beneficial microbiota such as those of the Bacillaceae family. The results showed that LC-PUFA enriched BSF meal associated with chitinase could be used as an effective alternative to fishmeal in order to improve protein digestion processes, beneficial microbiota and ultimately fish growth rate.