Black soldier fly larvae meal shows promise as soy substitute in broilers

A new broiler nutrition study in Veterinary Sciences examines whether black soldier fly larvae meal can stand in for soybean meal without compromising bird performance, meat quality, or health status. That question has become more commercially relevant as poultry producers and feed companies look for alternative proteins that can reduce dependence on soy while fitting within sustainability and circular-economy goals. The study tested graded replacement levels in Ross 708 broilers, giving the industry another controlled data point on how far substitution can go before performance or product quality starts to move. (poultryscience.org)

The backdrop is a fast-expanding research base around insect-derived feed ingredients, especially Hermetia illucens. Black soldier fly larvae have attracted attention because their amino acid profile can be competitive with conventional protein sources, and because they can be produced on side streams that would otherwise be wasted. At the same time, the science has been mixed enough to keep nutritionists cautious. Some broiler studies report stable growth and acceptable carcass outcomes, while others show reduced performance at higher inclusion levels or changes in digestibility and meat fat composition. A 2024 meta-analysis in Animal Production Science concluded that black soldier fly inclusion in broiler diets was generally safe up to about 10% of the diet, with outcomes shaped by form, dose, and feeding duration. (publish.csiro.au)

In the new Veterinary Sciences paper, researchers assigned 160 ten-day-old Ross 708 chicks to four diets in which black soldier fly larvae meal replaced soybean meal at 0%, 20%, 40%, or 60% on an equivalent basis, then followed birds through starter, grower, and finisher phases. According to the study summary provided, the team evaluated growth performance, carcass characteristics, meat quality, and blood biochemical responses. That design matters because it goes beyond weight gain alone and looks at whether a soy replacement changes indicators veterinarians and poultry integrators care about, including metabolic status and downstream product quality. (pubmed.ncbi.nlm.nih.gov)

The broader literature helps frame how to read the result. In one 2022 broiler study from ETH Zurich and collaborators, insect-based diets supported growth comparable to soybean-based diets in some groups, but breast meat lipids reflected the high lauric acid content of black soldier fly fat, raising questions about human-nutrition and meat-quality implications. Another broiler study reported that complete replacement of soybean meal with 16% defatted black soldier fly meal reduced available energy, nutrient digestibility, and growth performance, suggesting ingredient form and formulation precision are critical. Meanwhile, a large Animals trial using low inclusions of full-fat insect meals in 1,750 Ross 308 broilers found that 2% or 4% Hermetia illucens or Tenebrio molitor did not change feed intake, feed conversion, mortality, or overall growth, and breast yield was higher in insect-fed birds than in controls. But it also showed the kind of secondary effects nutritionists watch closely: birds fed 4% H. illucens had lower breast pH and higher cooking loss, thigh lipid deposition increased with insect inclusion, Tenebrio-fed birds had higher total and HDL cholesterol without a rise in LDL, and T. molitor specifically shortened ileal length. Taken together, the field is moving toward a more specific conclusion: black soldier fly can work, but not all black soldier fly ingredients behave the same way, and “no performance penalty” does not always mean “no biological differences.” (pubmed.ncbi.nlm.nih.gov)

There’s also a regulatory and quality-control angle. The Poultry Science Association notes that AAFCO updated the definition for dried black soldier fly larvae to cover poultry, swine, salmonids, and adult dog and cat foods, with the condition that larvae be raised on feed-grade materials. FDA has separately described black soldier fly larvae as an approved animal-food ingredient and has emphasized the broader preventive-controls framework that applies to animal food safety. For feed manufacturers and veterinarians, that means the conversation is no longer just about whether the concept is allowed, but whether sourcing, substrate controls, nutrient variability, contaminants, and labeling can be managed consistently enough for scaled use. (poultryscience.org)

The soybean side of the equation also deserves attention. Reducing soybean meal is not automatically neutral for bird biology, even before insect ingredients are added. In an Animals study of low-SBM broiler diets, a 10% reduction in soybean meal increased mortality and feed intake during days 22–42 and reduced ether extract availability, while also shifting the cecal microbiota toward higher relative abundance of Campylobacterota and Helicobacter. Adding raffinose partly modulated those changes and tended to reduce mortality, but it also lowered gross energy and dry matter utilization and downregulated a duodenal glucose transporter gene. For practitioners, that is a useful reminder that alternative-protein strategies have to be judged against the real consequences of moving away from soybean meal, not just against soy’s cost or sustainability profile.

Why it matters: For veterinary professionals working with poultry systems, the value of this study is less about novelty than about risk assessment. Soybean meal remains a highly familiar benchmark with well-characterized digestibility and formulation behavior. Black soldier fly meal offers a plausible alternative, but one that introduces new variables, including chitin content, fat profile, substrate-dependent composition, and possible shifts in blood chemistry or intestinal function. If the new study shows stable performance and health markers even at relatively high replacement levels, it strengthens the case for insect meal as part of a practical formulation toolkit. But the existing evidence still argues for caution around extrapolation across products, especially when moving between full-fat, defatted, larvae, prepupae, or oil fractions. (pubmed.ncbi.nlm.nih.gov)

Industry reaction has generally centered on sustainability potential, but experts keep returning to the same operational caveats: nutrient consistency, digestible amino acid values, and downstream effects on meat composition. The PSA summary, for example, highlights that nutrient composition varies with feedstock and warns that contaminants can accumulate if larvae are grown on polluted substrates. That makes veterinary oversight relevant not just for flock performance, but for feed safety, welfare, and food-chain confidence. Similar “threshold” thinking is showing up in other species as well. In grey mullet, partially defatted black soldier fly meal did not significantly impair growth across diets, but the highest replacement levels worsened intestinal condition and altered spleen findings, while a lower-inclusion diet appeared optimal for gut morphology and innate immune stimulation. That kind of species-specific ceiling effect reinforces the idea that black soldier fly ingredients are promising, but not infinitely interchangeable with conventional proteins.

It is also worth noting that insect ingredients are being explored for functions beyond simple protein replacement. A recent piglet study found that live Tenebrio molitor larvae improved early feed efficiency, supported growth and health after weaning, reduced diarrhea and respiratory problems, and helped a lower-protein diet perform comparably to a standard-protein control, without harming digestibility or serum metabolic markers. That does not directly answer the broiler soy-replacement question, but it does support the broader view that insect-based feeds may have behavioral or resilience-related benefits depending on species, form, and production stage. By contrast, other non-insect feed additives such as stevia extract are being studied mainly for meat-quality modulation in broilers, underscoring that feed innovation is now being judged on multiple outputs at once: performance, health, carcass value, and product quality.

What to watch: The next phase for this category will likely focus on standardizing ingredient specifications, defining economically optimal inclusion rates, and separating situations where black soldier fly meal is a straightforward soy substitute from those where it needs formulation support. More challenge-model studies, digestibility work, and commercial-scale trials should help clarify whether higher replacement levels can be used reliably in mainstream broiler production, or whether the strongest use case remains moderate inclusion with targeted health or sustainability benefits. Just as important, future work will need to keep tracking subtle endpoints — gut morphology, blood lipids, microbial shifts, water-holding capacity, and fatty acid profiles — because those are often where practical limits show up before headline growth metrics fail. (pubmed.ncbi.nlm.nih.gov)