Black soldier fly larvae show promise as partial soy replacement

A new Veterinary Sciences paper adds another data point to the fast-moving conversation around insect protein in poultry diets: black soldier fly larvae meal may replace a meaningful share of soybean meal in broilers, but only up to a point. In the study, low to moderate replacement levels, 20% and 40%, preserved growth performance, meat quality, and health-related measures, while the highest tested level, 60%, hurt productive outcomes. (mdpi.com)

That question has been building for years as poultry producers face pressure around feed cost volatility, soybean dependence, sustainability targets, and ingredient resilience. Black soldier fly larvae have drawn attention because they can be produced on side streams and offer a protein-and-fat package that is increasingly being studied across poultry species. Prior work has shown mixed results depending on inclusion level, processing method, bird type, and what exactly is being replaced in the formula. A recent meta-analysis concluded black soldier fly meal appears safe in broilers up to about 10% of the diet, while a 2023 systematic review found low insect meal inclusion generally performs comparably to conventional diets in broilers without intestinal challenge. (publish.csiro.au)

In the new study, the researchers used 160 ten-day-old Ross 708 chicks and tested four diets with 0%, 20%, 40%, or 60% black soldier fly larvae meal replacing soybean meal on a 100% equivalent basis. Their main conclusion was straightforward: partial replacement worked, but the highest inclusion level did not. According to the paper summary, birds on the 20% and 40% diets maintained growth performance, nutrient digestibility, physiological status, and meat quality, whereas birds on the 60% diet showed poorer productive responses. (mdpi.com)

That pattern broadly fits the wider literature. Other broiler studies have reported that moderate insect meal inclusion can preserve performance, while higher levels may introduce tradeoffs tied to digestibility, gut effects, carcass traits, or fatty acid shifts. One useful comparison comes from an Animals study of 1,750 Ross 308 broilers fed full-fat Hermetia illucens or Tenebrio molitor meal at 2% or 4% of the diet. In that trial, growth, feed intake, feed conversion, and mortality were unchanged across groups, and breast yield was actually higher in insect-fed birds than in controls. At the same time, some secondary effects emerged: the higher black soldier fly treatment was linked to lower breast pH and greater cooking loss, thigh meat showed dose-dependent lipid accumulation, Tenebrio increased total and HDL cholesterol without affecting LDL, and Tenebrio-fed birds had shorter ileal length. The overall message was still reassuring at low inclusion levels, but it also illustrated why “safe” does not always mean nutritionally identical in every downstream trait. (mdpi.com)

There is also a useful cautionary parallel in work on soybean meal reduction itself. In another broiler study, a diet with soybean meal reduced by 10% increased mortality and feed intake during the grower-finisher period and lowered ether extract availability, while also shifting the cecal microbiota toward more Campylobacterota and Helicobacter. Raffinose supplementation partly modulated some of those changes, including reversing the microbiota shift, but it also reduced some measures of energy and dry matter utilization. For practitioners, that study reinforces an important point: moving away from soybean meal is not automatically beneficial unless the replacement strategy preserves digestible nutrients, gut function, and microbial stability. (mdpi.com)

Research outside broilers points in the same direction. In grey mullet, partially defatted black soldier fly meal supported growth across diets, but intestinal and immune findings suggested a threshold effect: around 10% inclusion appeared optimal, whereas 20% was associated with worse intestinal condition and dose-related spleen changes. Different species obviously have different tolerances, but the broader lesson is familiar: insect ingredients may work best within a practical window rather than at maximal replacement levels. (mdpi.com)

The regulatory backdrop is also changing in ways that could make this research more commercially relevant. In AAFCO meeting materials published in 2025, dried black soldier fly larvae were listed for use in finfish, poultry, and swine feed, provided the larvae are raised on feed-grade materials and labeled appropriately. The same materials also show movement on black soldier fly larvae oil for poultry. That doesn’t settle every market-access or formulation question, but it does signal that insect-derived feed ingredients are moving further into the mainstream U.S. feed framework. (aafco.org)

There wasn’t a widely reported outside expert reaction tied specifically to this new paper in the search results, but the broader industry and academic commentary is fairly consistent: insect meals are promising as alternative proteins, yet they are not simple drop-in replacements. Reviews point to recurring formulation issues around chitin, mineral content, amino acid balance, and fat composition, all of which can influence digestibility, feed conversion, gut morphology, and final product quality. Other feed-additive research in broilers also shows how sensitive meat and production outcomes can be to formulation details: for example, stevia extract supplementation in yellow-feathered broilers altered multiple meat-quality-related parameters, including sensory and physicochemical traits, fatty acid and amino acid composition, and storage-related measures. In other words, the question is no longer just whether black soldier fly larvae can work, but under what nutritional conditions they work best. (mdpi.com)

Why it matters: For veterinarians, poultry nutritionists, and technical service teams, this study is useful because it sharpens the practical message. Black soldier fly larvae meal looks increasingly viable as a partial soybean meal replacement in broilers, which could help producers diversify protein sources and potentially improve supply-chain resilience. But the downside at 60% replacement is a reminder that “sustainable” and “nutritionally equivalent” are not the same thing. Advisers working with pet parents in backyard flocks, or with commercial poultry clients, will still need to pay close attention to formulation quality, ingredient consistency, and the difference between replacing a protein source on paper versus matching digestible nutrients in the bird. The broader literature supports that caution: low insect inclusion can be well tolerated and sometimes even favorable for carcass traits, but higher inclusion or poorly balanced low-soy diets can shift gut morphology, nutrient use, or health outcomes in ways that matter clinically and economically. (mdpi.com)

What to watch: The next phase will likely center on commercial validation, including cost-per-gain, digestible amino acid balancing, processing methods such as defatting, and whether regulators and feed-control bodies continue broadening approved insect ingredient uses in poultry diets. It will also be worth watching whether insect ingredients can deliver functional benefits beyond simple protein replacement. A recent piglet study found live Tenebrio molitor larvae were rapidly consumed, improved early feed efficiency and growth, lowered diarrhea and respiratory problems, and helped maintain performance even when dietary crude protein was reduced. That does not translate directly to broilers, but it hints at a wider opportunity for insect-based feeds to support intake and resilience as well as formulation flexibility. If those pieces advance together, black soldier fly larvae meal could move from an experimental sustainability story to a more routine formulation tool.