Alternative Proteins for Feed: What Already Works and How to Formulate

Global animal protein production is growing at a pace that conventional plant and animal protein sources can't keep up with without increasing pressure on land, water, and greenhouse gas emissions. At the same time, ingredients like soybean meal and fish meal show structural price volatility that makes excessive dependence on these sources a real operational risk for any feed plant. This set of factors has, in recent years, been accelerating the development and adoption of alternative proteins as viable ingredients for animal nutrition.

This article doesn't treat the topic as a distant future trend. It treats it as an ongoing technical reality, with ingredients at different stages of maturity, each with its own nutritional profile, formulation challenges, regulatory limitations, and potential for partially replacing conventional sources. The goal is to give nutritionists and formulators an objective technical view of what each category of alternative protein delivers in practice, where it can already be used safely, and what still needs to be resolved before broader adoption.

Why the search for alternative proteins is structural

The pressure on conventional protein sources isn't cyclical. It has deep roots in three simultaneous, mutually reinforcing dynamics.

The first is growing global demand for animal protein. As per capita income rises in emerging countries and meat, egg, milk, and fish consumption expands, demand for feed grows consistently. That growing demand needs to be met without proportional expansion of deforestation and without further increasing pressure on already-stressed water resources.

The second dynamic is the supply vulnerability of conventional proteins. Fish meal, historically the most digestible protein available for aquaculture and young swine production, depends on fish stocks that already operate near their sustainable limit in several regions of the world. Soybean meal, the main protein source for poultry and swine in Brazil and worldwide, is subject to weather variations, trade policies, and exchange-rate swings that create recurring cost-pressure cycles for formulators.

The third dynamic is the growing demand for certifications and traceable practices from institutional buyers, retail chains, and export markets. Companies able to demonstrate the use of ingredients with a smaller environmental footprint and better traceability are increasingly favored in supplier-qualification processes.

In this context, alternative proteins don't need to completely replace conventional sources to be relevant. In many cases, partial substitution — which reduces dependence and improves the formulation's sustainability profile without compromising animal performance — is already a real gain.

Insect meal: from research to commercial use

Among the alternative proteins that have advanced the most in recent years, insect meal stands out for combining high nutritional value, production efficiency, and growing scientific backing. The most studied and commercially relevant species is the black soldier fly (Hermetia illucens), whose larvae are raised on organic substrates and processed into meal with protein content typically ranging between 40% and 50% on an as-fed basis, with an essential amino acid profile that compares favorably to soybean meal.

Nutritional composition and digestibility

Protein from Hermetia illucens larval meal shows good digestibility in poultry and swine, with standardized ileal digestibility coefficients (SIDC) for essential amino acids like lysine, methionine, and threonine reported in studies between 75% and 90%, depending on the processing applied. Fat content can be high (between 10% and 35% in the whole larva) and, when not removed during processing, contributes significantly to the ingredient's energy value, but also increases the risk of rancidity during storage.

Chitin, present in the insect cuticle, has been studied both as a factor limiting protein digestibility and as a compound with potential prebiotic and immunomodulatory effects in poultry and swine. At high inclusion levels, chitin content can reduce the digestibility of other dietary nutrients, which is why practical inclusion limits are set.

Inclusion limits and target species

In broilers, studies indicate that partially replacing soybean meal with insect meal at inclusion levels of 5% to 10% doesn't compromise production performance and, in some studies, improves gut health parameters. In carnivorous fish such as salmon and tilapia, replacing fish meal with insect meal has been tested at higher levels, with promising results in species that tolerate chitin better. In swine, performance data in growing and finishing phases are positive at moderate inclusions, though comparative cost remains a relevant limitation.

Regulatory status in Brazil

In the European Union, the use of insect meal in poultry and swine feed was authorized in 2021, expanding on regulation that had previously only been established for aquaculture in 2017. In Brazil, MAPA still has no specific, consolidated regulation for the use of insect meal in feed for production animals, which is the main barrier to this source's commercial expansion in the domestic market in the short term. Experimental production and some niche-market uses already exist, but the absence of clear normative guidance limits scale.

Algae and microalgae: differentiated potential by species and function

Algae represent a heterogeneous category of ingredients with quite distinct applications among themselves. It's important to distinguish the use of microalgae as a protein source from the use of macroalgae as a functional additive, since the mechanisms of interest and the challenges differ in each case.

Microalgae as a source of protein and fatty acids

Microalgae such as Spirulina (Arthrospira platensis) and Chlorella vulgaris have very high protein content, often between 55% and 70% on a dry-matter basis, with a complete essential amino acid profile. Spirulina has been used in pet food and in small inclusions in poultry and aquaculture feed, with positive effects on pigmentation, immunity, and gut health parameters documented across several species.

The main obstacle to using microalgae at industrial scale in animal production feed is production cost, which is still much higher than conventional protein sources. Producing Spirulina and Chlorella in photobioreactors has a unit cost that makes inclusion in commercially produced poultry and swine feed unfeasible, except in high-value-added products. The prospect of viability depends on the scalability of cultivation systems and the cost reduction that comes with any technology's maturation.

Macroalgae and reducing methane emissions in ruminants

One of the most discussed advances in recent years in the field of alternative ingredients is the use of the red macroalgae Asparagopsis taxiformis as an additive in ruminant diets to reduce enteric methane emissions. Research published in high-impact scientific journals has shown methane emission reductions of more than 50% with inclusions below 0.5% of the diet's dry matter, thanks to the bromoform compound present in the alga, which inhibits methanogenesis in the rumen.

Despite the effectiveness demonstrated in research, commercialization at scale still faces challenges related to consistently producing the alga with stable levels of the active compound, product stability during storage and transport, production cost, and regulatory questions about the use of halogenated compounds in animal feed. In the Brazilian context, where cattle farming has great economic relevance and growing pressure to reduce its carbon footprint, interest in this line of research is significant.

Single-cell proteins: established ingredients and emerging technologies

The single-cell protein category brings together sources at very different stages of commercial maturity, from ingredients with decades of established use to technologies still at pilot scale.

Brewer's yeast and fermentation yeasts

Dried brewer's yeast (Saccharomyces cerevisiae) is one of the oldest and most established alternative ingredients in Brazilian animal nutrition. With protein content between 40% and 50% on a dry-matter basis and an interesting profile of nucleotides, beta-glucans, and mannan-oligosaccharides with documented prebiotic effects, yeast is a well-characterized ingredient with known nutritional matrices and use widely established in poultry, swine, cattle, and aquaculture feed.

Yeast's nutritional challenge is its relatively low methionine content, which requires specific supplementation when it replaces part of the soybean meal in poultry and swine diets. In addition, its nucleic acid content, which converts into uric acid in metabolism, imposes more conservative inclusion limits in some species, especially in young, high-performance animals.

Gas protein and next-generation SCP

A technological frontier receiving growing investment is producing single-cell proteins from gases or electricity, using chemoautotrophic or heterotrophic bacteria that convert carbon dioxide, hydrogen, or methane into protein biomass. Companies like NovoNutrients and Solar Foods, among others, are developing industrial processes that produce meals with 60% or more protein from substrates that don't compete with conventional agriculture.

The commercial viability of these technologies depends on reducing energy costs and on the industrial scale of the fermentation processes. The first commercial products are reaching the aquaculture and pet food markets, where willingness to pay for high-purity proteins is greater. Inclusion in industrial-scale production animal feed is still subject to proving economic viability in the coming years.

Agricultural byproducts and industrial co-products: the most accessible alternatives

For formulators working in the Brazilian market today, the category of alternative proteins with the greatest potential for immediate impact isn't the most technological one: it's agricultural byproducts and industrial co-products with relevant protein composition and reasonable regional availability.

Oilseed meals beyond soy

Canola meal and sunflower meal are protein sources with 35% to 40% crude protein content and an amino acid profile distinct from soybean meal, notably methionine, which is comparatively more abundant in sunflower meal. The main antinutritional factor in canola meal is glucosinolates, which at high inclusion levels affect thyroid function in poultry and swine. Low-glucosinolate canola varieties, known as canola 00, substantially reduce this risk and allow higher inclusions.

Sunflower meal's limitation is its high crude fiber content when produced with hulls, which restricts its use in high-requirement phases like growing broilers and piglets. When dehulled, its nutritional profile improves significantly, though the processing adds cost.

Distillery and grain-processing co-products

With the expansion of corn ethanol in Brazil, dried distillers grains with solubles, known by the acronym DDGS, have become increasingly available in the domestic market. Corn DDGS has protein content between 26% and 30%, with high amino acid digestibility and relevant energy value, but also significant compositional variability depending on each ethanol plant's production process.

This variability makes DDGS an ingredient that requires systematic laboratory analysis of each received batch before it's incorporated into formulas. Using fixed table values for this ingredient is one of the most common mistakes leading to unexplained nutritional deviations in feeds that use it.

Fermentation as a nutritional-value-enhancement technology

Solid-state fermentation and submerged fermentation are technologies that have been successfully applied to improve the nutritional value of byproducts with a high presence of antinutritional factors. Fermentation by filamentous fungi or lactic acid bacteria degrades phytates, glucosinolates, tannins, and other compounds that limit digestibility, while it can increase digestible protein concentration through substrate concentration. Fermented soy flours and fermented-yeast-based products with partially hydrolyzed cell walls are examples of ingredients that combine the characteristics of a conventional source with the added value of a biotechnological process.

The formulation challenges with alternative proteins

Regardless of the category of alternative protein under consideration, incorporating it into formulation efficiently requires attention to a set of challenges that recur, with variations, across sources.

The first challenge is nutritional variability. Alternative sources at early stages of commercial maturity tend to show greater compositional variability than conventional ingredients with decades of standardized production. This means the nutritional matrices used in formulation software need to be built and updated based on actual analyses of batches available in the market, not just literature values. Systematic receiving analyses and periodically updating matrices are indispensable practices for any formulator working with these ingredients at scale.

The second challenge is antinutritional factors specific to each source. Chitin in insects, glucosinolates in canola meals, tannins in tropical legumes, soluble fiber in algae, nucleic acids in yeasts: each alternative ingredient brings its own compounds that, in excess, limit digestibility and can affect animal performance or health. Setting safe inclusion limits requires technical knowledge of the ingredient's profile and, ideally, experimental evaluation in the target species and production phases.

The third challenge is palatability. New ingredients may be nutritionally adequate but have organoleptic characteristics that reduce voluntary feed intake, especially in early phases like broiler pre-starter, nursery piglets, or juvenile fish. Palatability testing is part of the qualification protocol for any ingredient entering formulas for these animal categories.

The fourth challenge is economic. The viability of using an alternative protein doesn't depend only on its unit cost, but on its cost-per-unit-of-delivered-nutrient ratio compared to available conventional sources. A meal with 40% digestible protein can be competitive against soybean meal with 46% if the price per ton is sufficiently lower and if the limiting amino acids can be synthetically supplemented without compromising the cost equation. This analysis can only be done precisely within formulation software that compares sources in terms of nutrients delivered per unit of cost, treating synthetic amino acids as part of the set of available ingredients.

How to strategically incorporate alternative proteins into formulation

Adopting alternative proteins at scale doesn't start with the maximum possible replacement of a conventional source. It starts with careful technical qualification followed by a gradual introduction that lets the formulator validate the ingredient's performance under their operation's specific conditions.

The qualification process begins with fully characterizing the ingredient's nutrition, with in-house analyses of at least three to five different batches to understand the actual range of compositional variation. Next, a period of controlled animal trials is recommended, starting with conservative inclusions below the limits reported in the literature, monitoring zootechnical performance, feed intake, and, when possible, gut health parameters.

Once safe inclusion is validated, the ingredient can be added to the portfolio of raw materials available in the formulation software, with a nutritional matrix calibrated from in-house analyses and inclusion limits set by the trials performed. From there, it naturally enters the least-cost optimization process, being used when and in the proportion that it's economically advantageous relative to available conventional sources.

This cycle of qualification, testing, validation, and gradual adoption is what allows alternative proteins to stop being technical curiosities and become regular ingredients in the formulation portfolio, contributing both to cost reduction and to diversifying the supply portfolio and the products' sustainability profile.