Study tests black soldier fly larvae meal in broiler diets

Black soldier fly larvae meal is getting another look as a soybean meal substitute in broilers, and a newly published Veterinary Sciences study adds to the case that poultry diets can absorb at least partial replacement without obvious performance penalties. In the trial, researchers assigned 160 Ross 708 broilers to diets where black soldier fly larvae meal replaced soybean meal at 0%, 20%, 40%, or 60% from 10 to 42 days of age, then measured growth performance, carcass traits, meat quality, and blood biochemical responses. The paper frames the work around a familiar industry challenge: how to reduce dependence on soybean meal while preserving bird health, carcass value, and feed efficiency. (mdpi.com)

That question has been building for years. Soybean meal remains a cornerstone of broiler formulation, but it also sits at the center of cost, supply, and sustainability debates. Insect-derived proteins, especially Hermetia illucens, have drawn interest because they can be produced on by-products, offer a competitive amino acid profile, and contain bioactive compounds such as lauric acid and chitin that may influence gut and immune responses. A recent Frontiers in Animal Science paper described black soldier fly larvae as a promising alternative to soybean meal and fishmeal, while also noting ongoing concerns around digestibility, fat deposition, substrate quality, contamination risk, and cost-effectiveness at commercial scale. (frontiersin.org)

The new Veterinary Sciences paper is notable because it looked beyond weight gain alone. According to the article record, the team evaluated daily weight gain, feed intake, feed conversion ratio, carcass traits, meat quality, and blood biochemistry across starter, grower, and overall periods. That broader design matters because insect ingredients often look acceptable on top-line growth, but questions remain about liver-related markers, mineral balance, oxidative status, and downstream meat characteristics. Earlier broiler work summarized by the Poultry Science Association found black soldier fly oil could replace soybean oil without harming growth performance, though higher replacement levels were associated with changes in aminotransferase and blood urea nitrogen, reinforcing the idea that “works” and “optimal” aren’t always the same thing. (mdpi.com)

Other broiler studies help sharpen that point. In an Animals trial involving 1,750 Ross 308 males, adding full-fat Hermetia illucens or Tenebrio molitor meal at 2% or 4% did not affect growth performance, feed intake, feed conversion, mortality, or overall carcass quality. Breast yield was actually higher in insect-fed groups than in controls, suggesting some production upside at low inclusion levels. But the same study also picked up subtler shifts: the HI4 group had lower breast pH and higher cooking loss, thigh meat showed dose-dependent lipid accumulation in insect-fed birds, T. molitor diets increased total cholesterol alongside HDL without changing LDL, and T. molitor was associated with shorter ileal length. In other words, low-level inclusion looked safe and productive, but not biologically invisible. (mdpi.com)

The wider literature is moving in a similar direction: moderate inclusion appears more reliable than aggressive substitution. A 2025 Frontiers study proposed a phased feeding strategy of 5% inclusion in the starter phase and 10% in the grower phase, then removal in the finisher phase, partly to manage digestibility, carcass quality, and cost concerns. Older broiler reporting cited by Feed Strategy likewise found that replacing half the soybean meal with defatted black soldier fly larvae meal did not adversely affect meat quality. And importantly, not every low-soy strategy performs well on its own. An Animals study of Cobb broilers found that a diet with soybean meal reduced by 10% increased mortality and feed intake during days 22–42 and reduced ether extract availability, while also shifting cecal microbiota toward higher relative abundance of Campylobacterota and Helicobacter. Adding graded raffinose partly modulated those changes and tended to reduce mortality, but also lowered some measures of nutrient utilization. That is a useful reminder that reducing soybean meal is not automatically equivalent to improving the diet; the replacement ingredient and the formulation strategy matter. (frontiersin.org)

Industry and expert commentary has been consistent on one point: formulation details and substrate controls are everything. The Poultry Science Association’s 2024 interpretive summary emphasized that nutrient composition can vary with larval feedstock and that heavy metals or other contaminants can accumulate if substrates are poorly controlled. The same summary also highlighted a regulatory boundary that matters for U.S. veterinarians and nutrition advisers: black soldier fly larvae for poultry feed must come from feed-grade substrates under the applicable AAFCO definition. In Europe, the regulatory environment has been more explicitly supportive of insect protein expansion in poultry and pig feed since Regulation (EU) 2021/1372. (poultryscience.org)

Threshold effects are another recurring theme across species. In flathead grey mullet, for example, an Animals study found that partially defatted black soldier fly meal did not significantly impair growth overall, but higher inclusion levels were associated with poorer condition factor, worsening intestinal histology, and spleen changes, while a lower-inclusion diet appeared to support intestinal morphology and innate immune stimulation without harming performance. Fish are not broilers, of course, but the pattern is familiar: insect ingredients may offer a useful nutritional tool, yet benefits can give way to tradeoffs once inclusion rises beyond a species- and diet-specific sweet spot. (mdpi.com)

Why it matters: For veterinary professionals, this is less a novelty story than a feed-risk management story. If black soldier fly larvae meal can reliably replace part of soybean meal while maintaining growth, carcass quality, and acceptable health markers, it gives poultry systems another lever when soybean pricing, sourcing, or sustainability targets become more difficult. But veterinarians advising integrators or feed programs will still need to ask practical questions: Was the ingredient defatted or full-fat? What substrate was used? How consistent is the amino acid profile lot to lot? What happens to liver enzymes, gut health, litter quality, and carcass composition at higher inclusion levels? The research trend is encouraging, but it still points toward controlled inclusion, not blanket substitution. It also suggests that “soy reduction” should not be treated as a win by itself; poorly balanced low-soy diets can carry their own mortality, nutrient-use, and microbiome penalties. (mdpi.com)

There’s also a pet parent-facing angle, even if this study is squarely about broilers. Insect proteins are already familiar in companion animal nutrition discussions, and poultry-sector validation tends to strengthen the broader narrative that these ingredients are moving from niche to mainstream. Work outside poultry is adding to that perception: a recent Frontiers in Veterinary Science study reported that live Tenebrio molitor larvae improved early feed efficiency, growth, and health indicators in post-weaning piglets, even allowing a moderately reduced crude-protein diet to perform comparably to a standard-protein control. That does not make species-to-species extrapolation appropriate, but it does show why insect ingredients are being discussed less as novelty proteins and more as functional feed tools. Still, animal health professionals will want to separate sustainability messaging from evidence-based feeding decisions. Performance parity in a controlled trial doesn’t automatically translate to commercial readiness if ingredient cost, supply reliability, or regulatory compliance lags behind. (poultryscience.org)

What to watch: The next step is likely more commercial-scale validation, especially trials that compare full-fat versus defatted ingredients, define upper inclusion thresholds by growth phase, and track health and meat-quality endpoints long enough to support field adoption. There is also likely to be continued interest in complementary feed strategies that shape meat quality or help offset formulation tradeoffs as conventional protein inputs are reduced. Regulatory clarity and ingredient standardization will matter just as much as biology. (frontiersin.org)