Nutritional evaluation of frass from black soldier fly larvae as potential feed ingredient for Pacific white shrimp, Litopenaeus vannamei

Authors: Aksoy, Mediha; Eljack, Rashida; Beck, Benjamin; PEATMAN, ERIC - Auburn University

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2022
Publication Date: 10/4/2022
Citation: Aksoy, M., Eljack, R.M., Beck, B.H., Peatman, E. 2022. Nutritional evaluation of frass from black soldier fly larvae as potential feed ingredient for Pacific white shrimp, Litopenaeus vannamei. Aquaculture. 27:101353. https://doi.org/10.1016/j.aqrep.2022.101353.
DOI: https://doi.org/10.1016/j.aqrep.2022.101353

Interpretive Summary: Global aquaculture production of the Pacific white shrimp (Litopenaeus vannamei) has grown dramatically within the last two decades and now represents over 71% of all marine shrimp produced. With over $11 billion in value in 2010, and accounting for 15 percent of the total value of internationally traded fishery products, it is currently the most valuable single aquaculture commodity. Future growth and profitability within the shrimp aquaculture sector are dependent upon continued improvements in diet efficiency and formulation since feed is the largest input cost for most aquaculture operations, including shrimp. Growth in aquaculture demand and declining resources are increasing the price of fishmeal and fish oil, which is, in turn, driving demand for more sustainable alternatives to conventional protein sources. In recent years, insects have received wide attention as a potential source of protein both for humans and livestock-including fish and insect-based protein meals- which can be used as a more sustainable alternative to conventional protein (fish or plant protein meals) used in aquaculture. Black soldier fly larvae are currently uncompetitive with fishmeal; however, producers are scaling up insect production to meet increasing global demand for protein and reduce the cost of insect meal. Moreover, after larvae are harvested, considerable amounts of larvae excrements are left behind. Frass, the left-over product from growing black soldier fly larvae, fed DDGs with solubles, contains about 20% protein and abundant beneficial nutrients, chitin, and beneficial microbes as well. We recently demonstrated that larvae frass from black soldier fly byproduct has a specific growth promoting effect on channel catfish and hybrid tilapia through increasing palatability and feed intake. Formulating efficient and affordable diets with readily available ingredients is critical to commercial aquaculture species. This can be achieved by investigating the potential use of novel ingredients – such as larval frass. Therefore, the present study aims to assess the nutritional value of larvae frass of black soldier fly byproduct on weight gain, whole-body and fillet proximate composition, and hemolymph parameters of Pacific white shrimp. Five isocaloric diets containing frass at levels of 0, 5, 10, 20 and 30% as partial replacement of a combination of soybean meal (SBM), cottonseed meal (CSM), wheat short (WS), and corn meal (CM) on an equal protein basis were offered four times daily for 12 weeks to Pacific white shrimp. No significant differences were observed in final weight gain, survival, and whole-body composition of shrimp fed up to 30% dietary frass. However, shrimp fed 20% and higher dietary frass level had significantly lower levels of fillet lipid. Serum from shrimp fed 20% dietary frass significantly increased inhibition of Vibrio parahaemolyticus growth when compared to that of the control group. However, other hemolymph parameters were not significantly affected by dietary treatments. Frass can be incorporated in shrimp diets up to 30% as a substitute for a combination of SBM, CSM, WS and CM without negative effect.

Technical Abstract: Frass is a by-product of the larval meal industry and is currently readily available and competitively priced relative to larva meal. In addition to generally high protein and fat content (21.6% and 6%, respectively), frass contains abundant nutrients, chitin, and beneficial microbes. This study evaluates the effect of various levels of frass derived from the larvae of black solder flies fed dried distillers’ grains (DDG) with solubles on growth performance, whole body and fillet proximate compositions and selected hemolymph parameters of Pacific white shrimp, Litopenaeus vannamei. Five isocaloric diets containing frass at levels of 0, 5, 10, 20 and 30% as partial replacement of a combination of soybean meal (SBM), cottonseed meal (CSM), wheat short (WS) and corn meal (CM) on an equal protein basis were offered four times daily to Pacific white shrimp. Four replicate groups of 15 shrimp per tank (initial weight 4.06 ± 0.05g) were offered experimental diets at 4% total body weight daily for 12 weeks. Shrimp in each aquarium were group-weighed and counted at 2-week intervals and feed inputs were adjusted based on observed survival and weight gain. No significant differences were observed in final weight gain, survival, and whole-body composition of shrimp fed up to 30% dietary frass. However, shrimp fed 20% and higher dietary frass level had significantly lower level of fillet lipid. Serum from shrimp fed 20% dietary frass significantly increased inhibition of Vibrio parahaemolyticus growth when compared to that of the control group. However, other hemolymph parameters (total hemocyte count, hemocyanin, serum protein and serum cholesterol) were not significantly affected by dietary treatments. Frass can be incorporated in shrimp diets up to 30% as a substitute for a combination of SBM, CSM, WS and CM without affecting their growth performance, body composition, hemolymph parameters.