Can Antibiotic Growth Promoters Be Replaced with Phytogenic Feed Additives?

The use of AGPs in the animal feed industry has been decreasing due to their link with antimicrobial resistance. Concerns around increasing levels of antimicrobial resistance has resulted in AGP bans in several countries. In 2006, the use of AGPs in animal feed was banned in the EU. In 2017, the Food and Drug Administration (FDA) brought in new rules sharply curtailing the routine use of antibiotics on farms across the US.

Since the restriction of AGPs, the animal feed industry has faced the big problem of finding adequate replacements in order to sustain and even increase output to meet the growing demand for animal protein worldwide. The main mode of action of AGPs is assumed to be their antiinflammatory properties (Niewold, 2007), hence alternative products with similar effects on the inflammatory system are highly sought after.

PFAs are an alternative to AGPs

One alternative to AGPs are PFAs. PFAs have been used as natural performance enhancers for many centuries. PFAs are extracted from plants of different origins and include essential oils from herbs and spices, single essential oil compounds, plant extracts and mixtures thereof (Figure 1). PFAs have a broad spectrum of chemical compounds depending on their origin, extraction method and mode of application.

There are several PFAs commercially available on the market, ranging from products providing powder or essential oil from a single plant, to highly specialized PFAs comprising a mixture of different essential oils from herbs and spices and plant extracts. Such highly specialized PFAs have the advantage of showing additive and synergistic effects on animal performance.


Figure 1. The origins of phytogenic feed additives

Source: BIOMIN
The origins of phytogenic feed additives

Figure 2. Digestarom® mode of action

Source: BIOMIN
Digestarom®​​​​​​​ mode of action

Knowing what is in your PFA

It is very important to know the composition of the PFA to better understand its mode of action. BIOMIN supplies the phytogenic product line Digestarom®, a specialized PFA with a proven mode of action consisting of essential oils from herbs and spices, and non-volatile extracts.

Digestarom® works in a number of ways (Figure 2) including:

  • Enhancing the palatability of feed
  • Increasing endogenous enzyme secretions
  • Improving nutrient digestibility
  • Modulating the gut microbiota
  • Suppressing inflammatory processes
  • Protecting the gut and promoting gut health All of these effects lead to optimized feed conversion and performance enhancement.

Palatability improvements

Digestarom® has sensory effects due to its volatile aroma and active constituents. These influence the smell (olfactive) and taste (gustatory) perception of the animal, enhancing the palatability of the feed, and promoting and supporting feed intake. These sensory properties are of major relevance since many animal species have more taste buds than humans, making them more susceptible to taste perception. Additionally, it has been shown that Digestarom® stimulates the release of endogenous enzymes such as maltase, sucrase and aminopeptidase, which results in better carbohydrate and protein digestion. Furthermore, the digestibility of essential amino acids can be improved with the inclusion of Digestarom®, which contributes to better animal performance and can provide nutrient-sparing effects.

Improving intestinal morphology

When Digestarom® was included in the feed, positive effects on intestinal morphology were demonstrated. Villi length increased, which resulted in an enhanced epithelial surface, and crypt depth decreased, which resulted in improved nutrient absorption.

gut microbiota of the animal. The main effects are a reduction in the total microbial number (aerobic and anaerobic) and a decrease in the pathogenic Gram-positive bacteria Staphylococcus aureus and Clostridia. At the same time, Digestarom® promotes the growth of beneficial bacteria such as Lactobacilli. This shift towards more eubiotic conditions in the gut contributes to fewer intestinal challenges, e.g. a reduction in the inflammatory processes in the gut wall.

Direct anti-inflammatory effects

Digestarom® also demonstrates direct anti-inflammatory effects through the down-regulation of NF-κB mediated intestinal inflammation markers (IL-6, ICAM-1, MCP-1), and increases cell protective effects by up-regulating Nrf2 mediated gut protection markers (CYP1A1, HO-1, UGT1A1). Hence, the animal is relieved from intestinal stress, meaning that energy can be utilized for optimizing performance rather than for fighting inflammation.


Digestarom®, a specialized PFA consisting of essential oils from herbs and spices and non-volatile extracts optimizes feed conversion and improves animal performance. With its proven mode of action, Digestarom® is therefore a powerful tool in any AGP replacement strategy.


Digestarom® is an effective replacement for AGPs thanks to:

  • its volatile aroma and active constituents that improve the palatability of feed
  • its ability to stimulate the release of endogenous enzymes to improve nutrient digestibility
  • its positive effects on intestinal morphology, improving nutrient uptake
  • its effect on the gut microbiome, promoting the growth of beneficial bacteria
  • its direct anti-inflammatory effects, allowing more energy to be used for growth


Niewold, T, A. (2007). The Non-antibiotic Anti-Inflammatory Effect of Antimicrobial Growth Promoters, the Real Mode of Action? A Hypothesis. Poultry Science. 86(4). 605–609.