A recent study from the National Autonomous University of Mexico (UNAM) puts that question to the test. But before getting into the results, it’s worth understanding why this kind of research matters in the first place.
The poultry industry has spent years searching for alternatives to traditional growth promoters. With growing restrictions on antibiotic growth promoters (AGPs) in many markets, and constant pressure to improve efficiency without compromising animal health, functional nutrition has become an active field of research.
Within that search, fungal fermentation-based additives have gained ground as serious contenders. The logic behind them isn’t new: during fermentation, fungi like Aspergillus produce secondary metabolites — enzymes, organic acids, bioactive compounds — that the animal can use directly, without its own digestive system having to synthesize them from scratch.
Why the starter phase matters so much?
In broiler chickens, the first 21 days of life are an especially sensitive window. This is when the bird develops its digestive and enzymatic capacity, establishes its gut microbiota, and lays the groundwork for its immune system. Any challenge during this stage — heat stress, inconsistent raw material quality, mycotoxin exposure, or simply the shift from liquid to solid feed — can leave a mark on performance throughout the entire production cycle.
That’s why nutritional strategies aimed specifically at this phase carry outsized weight. It’s not just about feeding more — it’s about helping the bird digest and absorb what it’s already eating more efficiently, while keeping gut integrity intact under stress.
Where Aspergillus comes in?
Dried Aspergillus solubles fermentation meals sit right in that space. They’re credited with improving gut integrity, reducing systemic inflammation, and lowering oxidative stress — three factors that, left unchecked, tend to show up as worse feed conversion and lower weight gain.
Aspergillus oryzae in particular has shown benefits for feed conversion under conditions of stress or poor digestion. The proposed explanation is that its metabolites support nutrient absorption and help control mycotoxins and pathogens in the digestive tract.
So far, all of this sounds promising in theory. The real question for any nutritionist or producer is different: does this actually translate into measurable results under controlled conditions?
To find out, a team at the Center for Teaching, Research and Extension in Poultry Production (CEIEPAv), part of the School of Veterinary Medicine and Animal Science at UNAM, designed a trial with chicks during their first three weeks of life: they tested different amounts of the product in the feed and compared growth against a group that received none.
The results were clear: chickens given the mid-level dose grew noticeably more than the rest — around 750 grams of final body weight, compared to 716 grams in the group without the additive. Interestingly, they ate roughly the same amount of feed as the other groups. In other words, they didn’t grow more because they ate more — they grew more because they made better use of what they ate.
The finding points to an optimal dose rather than a simple “more is better” relationship — which lines up with how fungal metabolite-based additives tend to behave. The researchers themselves acknowledge a limitation: the study only covers the starter phase, and they recommend extending the evaluation to the full six-week production cycle to confirm whether the effect holds up in later stages.
For those formulating diets or evaluating functional additives, having controlled, academically-backed evidence — in this case, from UNAM — provides a stronger basis for deciding on inclusion of this type of product. The next step, as the researchers themselves point out, will be confirming whether this effect holds throughout the entire production cycle.
Source
Sánchez, K., Miguel Iriarte, J., Ávila, E., Priego, C., y Cortes, A. (2026). Evaluación de Pri-A-Ferm como promotor del crecimiento en dietas maíz-soya en pollos de engorda en iniciación [Informe técnico]. Centro de Enseñanza, Investigación y Extensión en Producción Avícola (CEIEPAv), Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México.
