Insect meals improved protein profile of maize silage in waterfowl study

A new Animals paper explores a niche but increasingly relevant feed question: whether insect meals can improve maize silage that might be used in waterfowl diets. In the trial, maize forage ensiled with a lactic acid bacteria inoculant and supplemented with either Hermetia illucens or Tenebrio molitor meal produced silages with higher crude protein than the inoculant-only control, while the black soldier fly treatment also increased fat content and calculated metabolizable energy for poultry. The microbial profile was largely unchanged across treatments, and mycotoxin shifts were selective rather than sweeping. (pmc.ncbi.nlm.nih.gov)

The work sits at the intersection of two longer-running trends: interest in lower-cost forage inclusion in ducks and geese, and interest in insects as alternative protein sources for livestock feeds. The study authors note that maize silage can help reduce reliance on concentrate feeds in waterfowl systems, but its low protein density limits its value unless it’s paired with a richer nitrogen source. They also point out that most insect-meal evidence in poultry still comes from broilers, with comparatively sparse data in ducks and geese. (pmc.ncbi.nlm.nih.gov)

In this experiment, the researchers compared five treatments after eight weeks of ensiling: lactic acid bacteria inoculant alone, inoculant plus urea, inoculant plus H. illucens meal, inoculant plus T. molitor meal, and inoculant plus lauric acid. The underlying insect ingredients were nutrient-dense: the black soldier fly meal analyzed at about 349 g/kg crude protein and 340 g/kg ether extract on a dry matter basis, while the mealworm meal analyzed at about 458 g/kg crude protein and 311 g/kg ether extract. In the finished silages, crude protein rose from 49.73 g/kg dry matter in the inoculant-only control to 64.94 g/kg with H. illucens and 67.32 g/kg with T. molitor; the H. illucens treatment also nearly doubled ether extract relative to control and produced the highest calculated AMEn value. (pmc.ncbi.nlm.nih.gov)

On hygiene and safety, the findings were more measured. Total viable count, coliform bacteria, lactic acid bacteria, and microscopic filamentous fungi did not differ significantly among treatments. Among the mycotoxins tested, only deoxynivalenol, fumonisin B1, and fumonisin B2 were consistently detected across silages, with deoxynivalenol present in all samples and at the highest concentrations overall. Compared with the control, deoxynivalenol was lower in the urea, black soldier fly, and mealworm groups, while fumonisin B1 was lower in the mealworm and lauric acid groups. Aflatoxins, ochratoxin A, and zearalenone were not detected. (pmc.ncbi.nlm.nih.gov)

There doesn’t appear to be much direct outside commentary yet on this specific paper, but the broader expert view is consistent: insect meals are promising, though not simple plug-in replacements. A recent Frontiers in Veterinary Science review describes insect meal as a nutritionally useful alternative protein source for poultry, while stressing that quality varies with rearing substrate and processing, and that contaminants such as mycotoxins, heavy metals, pesticides, and dioxins remain important control points. That substrate point is not theoretical. In a separate Frontiers in Veterinary Science study, black soldier fly larvae fed yellow wine lees performed best at moderate inclusion levels: replacing cornmeal and wheat bran with about 20% to 30% yellow wine lees improved larval growth efficiency and raised crude protein content to roughly 48%, while 40% to 50% inclusion suppressed growth, reduced microbial richness, and was associated with gut community imbalance, dietary acidification, and ethanol accumulation. Ether extract also increased as yellow wine lees inclusion rose. In other words, the nutritional quality of the insect ingredient entering a silage system can shift meaningfully depending on how the larvae were produced. EFSA has similarly said the biological and chemical hazards associated with insect-derived feed depend on how insects are produced, what they’re fed, when they’re harvested, and how they’re processed. (frontiersin.org; frontiersin.org)

Why it matters: For veterinarians, nutritionists, and technical teams advising poultry producers, this study is less about immediate ration reformulation and more about proof of concept. It suggests insect meals may improve the nutritional profile of silage-based ingredients for waterfowl without obvious deterioration in basic microbial quality. But it doesn’t answer the practical questions clinicians and feed advisors care most about yet: bird performance, liver and gut health, palatability, economics, consistency across batches, and how mycotoxin behavior changes under farm conditions. That caution is especially important because maize silage is already a known mycotoxin risk matrix, and insect-derived ingredients add another variable tied to substrate control and processing quality. The newer black soldier fly substrate work reinforces that point by showing that even before an insect meal reaches the feed mill, its protein, fat, and likely biological consistency can be shaped by the waste stream used to rear the larvae. (pmc.ncbi.nlm.nih.gov; frontiersin.org)

There’s also a regulatory and market context here. In the EU, processed animal protein derived from farmed insects has been authorized for use in poultry feed since August 2021 under specified production and cross-contamination controls, which has helped move insect protein from novelty toward commercial feed ingredient status. That doesn’t directly validate insect-supplemented silage as a standard practice, but it does mean the broader feed ecosystem is becoming more receptive to insect-based inputs. (food.ec.europa.eu)

What to watch: The next phase to watch is animal-level validation, especially duck and goose trials that connect silage composition with growth, feed conversion, immune outcomes, carcass traits, and residue or toxin surveillance. It will also be important to see whether future work standardizes or at least reports insect rearing substrates more clearly, because emerging evidence suggests those upstream production choices can affect the nutrient profile and biological quality of the insect meal itself. If those data are favorable, the conversation could shift from whether insect meals can alter silage chemistry to whether they can do so consistently, safely, and at a price point that makes sense for commercial waterfowl programs. (pmc.ncbi.nlm.nih.gov; frontiersin.org)