Type of black soldier fly (Hermetia illucens) larvae frass influences the nutritional value when included in a prepared diet for Mozambique tilapia (Oreochromis mossambicus)

Authors: ROMANO, NICHOLAS - University Of Arkansas At Pine Bluff; YAMAMOTO, FERNANDO - Mississippi State University; Rawles, Steven - Steve; Webster, Carl

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: With the global population expected to increase dramatically during the next 30 years, there is a distinct possibility that suitable land for crop production could become scarce. Further, with climate change affecting global agriculture production, use of new diet ingredients that do not compete with foods for human consumption and minimize adverse effects on the environment and the climate need to be evaluated. Insects may be a more sustainable alternative protein source than marine fish meal because they require small amounts of land for production. Insects contain substantial amounts of high-quality protein (up to 74.4% of dry matter) and a balanced amino acid profile. However, insect production generates waste (frass) that contain unconsumed substrate, manure, and hatched egg casings. This waste needs to be properly disposed of or used as a resource. This study evaluated frass from black soldier fly larvae, which had been grown on two different substrates, as a feed ingredient in diets for tilapia. One of the substrates was expired fish diet (EFD) while the other substrate was fruit/vegetable peelings (FV). Both types of frass were added at 5% and 10% inclusion level in the diets. After 8 weeks, tilapia fed a diet containing 10% EFD frass had higher growth rate and final body weight compared to fish fed all other diets. Further, when liver and intestines were examined, no changes were reported that would lead to health issues for the fish. Results indicate that addition of 10% EFD frass improved growth in tilapia without compromising health of the fish. This study shows that it may be possible to not only utilize waste from insect production in an aquaculture diet, but that in tilapia, addition of frass had production benefits.

Technical Abstract: Black soldier fly (Hermetia illucens) larvae (BSFL) farming is expected to increase and a by-product is the ‘frass’. Frass is the waste products of the insects along with the substrate used to grow the insects. The inclusion of BSFL frass has shown to enhance tilapia and catfish growth/immunity. However, the composition of BSFL frass, and potentially their nutritive value to fish, may depend on the initial provided substrate. In this 8-week nutrition trial, BSFL frass made from either expired fish diet (EFD; pellets designed for fish with a crude protein of 35%) or a combination of fruit/vegetable peels (FV) were included in the diets of Mozambique tilapia at 5 or 10%. The EFD and FV frass had a different nitrogen, mineral and amino acid profile, and this information was used to formulate the diets. Results showed that EFD frass at 10% significantly enhanced tilapia growth compared to control or those fed the 5 or 10% FV frass diets. There were no significant differences in the crude protein or lipid content of the fish, but some differences were observed in the amino acid and fatty acid compositions. Among the test minerals, only phosphorus was significantly affected which was higher in tilapia fed the FV frass diets. Liver histology showed some minor inflammation and blood vessel congestion in tilapia fed the 10% frass diets, while the intestinal histology had a better cumulative score among all the frass diets compared to the control. Results indicate that the initial substrate provided to the BSFL can substantially influence their nutritive value to fish and that addition of 10% EFD frass can improve growth of tilapia without causing adverse effects to the fish.