You can make history. Or an antibiotic-free future in animal nutrition: With phytogenics

More and more bacteria are becoming insensitive to antibiotics - even in animal husbandry. Read in this article what role phytogenics can play in antibiotic-free animal nutrition...

With all the available information about antimicrobials online and in social media, we would be excused to believe that they are a modern concept that can either save lives or lead to the death of millions of people because of its overuse and abuse.

Read in this article about:

  • the difference between antibiotics and antimicrobials
  • the history behind antibiotics
  • the actual legislation
  • the beneficial effects of phytogenics against bacteria

The word antimicrobial derives from the Greek anti (against), mikros (little) and bios (life) and refers to all agents that act against microbial organisms. It is not synonymous with antibiotics, a similar term derived from the Greek anti (against) and biotikos (concerning life). By strict definition, the word “antibiotic” refers to substances produced by microorganisms that act against another microorganism. This definition of antibiotics does not include antibacterial substances that are synthetic (sulfonamides and quinolones), or semisynthetic (methicillin and amoxicillin), or those which derive from plants (quercetin and alkaloids) or animals (lysozyme).

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All antibiotics are antimicrobials, but not all antimicrobials are antibiotics

In truth, antimicrobials have been used for a long time and there are records in ancient civilizations of the use of moldy bread in wounds in order to prevent infections. The use of antibiotics, one specific category antimicrobials, becomes particularly contentious when we speak about its use in farmed animals. Indeed the first recommendation of WHO guidelines over the “Use of Medically Important Antimicrobials in Food Producing Animals” is: “We recommend an overall reduction in use of all classes of medically important antimicrobials in food-producing animals.“

Back in 1928,

Fleming discovered penicillin, later to be claimed as the miracle drug of the 20th century, but its importance was not realized until the 1940s, when its applicability as a therapeutic agent was made possible by Florey and Chain. Since then antibiotics play a fundamental role in both animal and human health care.  

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Another major effect, discovered in the 1940s, of antibiotics in food producing animals has been it´s growth promoting effect and this use was common until the Regulation (EC) No. 1831/ 2003 that stated that, "antibiotics, other than coccidiostats and histomonostats, might be marketed and used as feed additives only until December 31, 2005. Anticoccidial substances also will be prohibited as feed additives before 2013. After this date, medical substances in animal feeds will be limited to therapeutic use by veterinary prescription.“ 

Abusive and irresponsible use of antimicrobials – such as antibiotics, both in human, veterinary health and animal food industry have been associated with the increase in antibiotic resistance. In recent days pressure is mounting to reduce its use and consumer groups are pushing even further, to completely eliminate its use in farmed animals. In this quest the health of the animals should never be compromised.

One of the most promising groups to bring the benefits of antimicrobials by controlling infections, modulating the immune system and improving growth are phytogenics.


Phytogenics are plant derived bio active compounds, natural growth promoters or non-antibiotic growth promoters used as feed additives. The term phytogenic feed additives was coined by Delacon, and was first introduced to the market in the 1980s.

The best known group of phytogenics are essential oils, but these are only one of the seven groups of phytogenics that may be combined together in order to achieve particular benefits in animals. Some essential oils and flavonoids (another group of phytogenics) for example have antimicrobial effect and are sometimes purported as a direct replacement of antibiotics, to achieve this effect however high levels of these compounds need to be included in the feed, and it may become less palatable.

Ever heard of Quorum sensing Inhibition?

A far more promising effect that can be achieved with phytogenics is bacterial quorum sensing inhibitionQuorum sensing is a mode of communication between bacteria that allows individual bacteria to sense if their population is large enough to work in synergy in order to reach a common goal, produce toxins, biofilm, adhesion factors, etc. This communication prevents individual bacteria from wasting energy in activities that are only successful if a large number of bacteria enrolls at the same time.


By interfering with quorum sensing, phytogenics disrupt the communication between bacteria, preventing them from sensing signals that would otherwise trigger them to produce toxins or to become invasive (i.e. it prevents pathogenicity). Instead of simply killing bacteria, Phytogenics make bacteria “blind and deaf” to the signals from the other bacteria, preventing these from becoming pathogenic or virulent.

Another way in which phytogenics bring benefits to animals is by increasing anti oxidative enzymes, immune modulation and direct free radical scavenging. Oxidative stress is an imbalance between the production of free radicals and the ability of the organism to counteract or detoxify their harmful effects through neutralization by antioxidants. Free radicals and oxidative stress are associated with increased cell ageing and early death, leading to a vicious cycle by increasing oxidative stress.

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One of the main purposes of using antibiotic growth promoters in the past was to improve the efficiency of feed usage and zootechnical performance of the animals. Phytogenics have been shown to positively impact the feed intake of animals but most importantly to improve the feed conversion ratio (FCR), key for sustainable farming maximizing the use of available resources.

So, in summary…

…antibiotics may still be necessary (even if the tendency is the total abolition, especially of the ones approved for human use) to ensure that animal´s health is safeguarded. But natural plant bio actives that allow us to control the pathogenicity and virulence of microbes, modulate inflammation and immunity, control free radicals and preventing oxidative stress are already available to us.
Phytogenics tick all the boxes allowing better farming practices and a sustainable production of animal protein in an antibiotic-free way.

Ricardo Neto

Ricardo Neto

Ricardo Neto was part of the Delacon PDI team as CTS manager swine from February 2019 until early 2020. Ricardo is a Doctor of veterinary medicine, graduated from UTAD in Portugal and he worked in a specialized pig practice in England for 4 years. After this period in practice, he joined the pharmaceutical industry launching the first PCV2 vaccine in the UK and Ireland and later the first Swine influenza vaccine. He joined the global repro team to support the reproductive franchise providing training and regional support. Ricardo is passionate about sustainable and ethical pig production.

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