Circularizing dairy waste: Scientists investigate black soldier fly larvae for animal feed

30 Nov 2023 --- US-based scientists are targeting dairy waste reduction by mass producing the black soldier fly that feeds on it and evaluating the insect’s potential as a feed for livestock, including poultry, swine, fish and domestic pets.

The new project aims to explore the environmental health and economic benefits of converting dairy waste into protein for feed, with the post-digestion residue acting as a fertilizer.

“Black soldier fly larvae are high in protein and fat,” Dr. Jeffery Tomberlin, director of the Center for Environmental Sustainability through Insect Farming and one of the lead authors of the study, tells Food Ingredients First. 

“Furthermore, they contain many of the key nutrients necessary for livestock, poultry and other animals growth and production.”

“Such work could result in the diversification of the F&B industry based more on a circular economy by taking a material of minimal value like manure and converting it to products of value such as animal feed and fertilizer,” he underscores.

He adds that the interest in providing insects as feed to animals faces far less resistance than feeding insects to people.

Inside the study
The study will be conducted at the Texas A&M College of Agriculture and Life Science Department of Entomology and Mississippi State University, US. The researchers have received a three-year, US$618,000 grant from the US Department of Agriculture National Institute for Food and Agriculture.

Black soldier fly larvae will be placed in tubs with dairy manure to test their ability to consume waste and convert it into safe protein (Image credit: Texas A&M AgriLife).During the process, black soldier fly larvae consume their weight in organic waste daily for two weeks — around 1 g or the weight of a single raisin per larva. 

The scientists explain that these seemingly small amounts add up when multiplied by millions of black soldier fly larvae.

There are facilities in Europe, Asia and North America that can digest 100 metric tons of waste daily using black soldier fly larvae.

The experiments are done in plastic containers filled with around 18 lbs of manure where 10,000 black soldier fly eggs are placed. The larvae hatch, consume the dairy manure for two weeks and are then harvested. The process is then repeated.

Once this procedure is complete, Heather Jordan, associate professor and microbiologist at Mississippi State University, will inspect the resulting larvae and frass — the material remaining after larvae digest manure — for microbial diversity and feed safety.

Efficiency and safety aspects
Black soldier flies consume organic waste, including manure, but the waste conversion process leaves room for efficiency improvements, state the researchers.

The study will utilize probiotics to enhance the black soldier fly waste conversion of dairy manure and remove more than 50% of nitrogen and potassium from the waste.

Tomberlin explains: “Probiotics can manipulate the resource so that it is more easily digested by the black soldier fly larvae — much like when people consume probiotics for themselves.”

The project supports the circular economy, managing dairy waste by utilizing black soldier flies’ natural feeding cycles.Early data from the study indicates that probiotics could accelerate the digestive process in fed animals, increase the conversion of waste to insect biomass, decrease greenhouse gasses and noxious odors and reduce concerns about pathogens that might be present in the manure.

Meanwhile, Dr. Anjel Helms, a chemical ecologist at the Department of Entomology and another lead author of the study, flags that the team is “testing the limits” of black soldier fly production in conjunction with probiotics to see how efficient they could be for animal production facilities.

“Manure management is an expense to these producers, and we are testing to see if this is a way to manage that waste and turn it into a productive feed source.”

An essential part of the project is determining how “safe” harvested larvae are when converted into ingredients for feed, underscore the researchers. There is limited knowledge about pathogen diversity in larvae that consume manure, which could impact feed safety.

Helms suspects larvae consuming manure are safe for livestock consumption, but the end product requires certification.

Beyond waste management
Manure conversion by black soldier flies is also expected to provide an environmental benefit beyond reducing reliance on traditional manure management methods like waste storage lagoons.

“There is potential for layers of economic and environmental benefits to incorporating black soldier flies in manure management,” states Helms.

“Turning waste into a resource sounds too good to be true, but we are understanding more and more about how black soldier flies can solve many problems.”

As Tyson Foods told us last month, black soldier flies can eat up to twice their body weight daily, which the company uses to enable a closed-loop recycling system. It is creating a reusable protein source to reduce land and water resource demands through the effective use of animal by-products.

Regarding other insects with the potential to tackle food waste, Tomberlin indicates a “definite interest” in crickets and mealworms.

By Insha Naureen