Phytogenics: overall potential as an alternative to AGPs

Feeding the world is an important objective since the rising global population comes with an increasing demand for food. Addressing this challenge, animal production transformed during time from a basic need to a significant economic sector: The value of global livestock production in 2013 has been estimated at about 883 billion dollars. Hence, several strategies were applied to maximize animal production with always keeping the farm’s profitability in mind: besides the establishment of breeding lines selected for fast fattening animals, the development of special feed and feed additives, which are adapted to the particular needs of the target animals, represents a crucial factor for the profitability of state-of-the-art animal production.
Taking the first steps with antibiotics
In modern agriculture, antibiotics have been routinely used as growth promoters in animal feeding. Consequently, the widespread application of antibiotic growth promoters has strongly contributed to the development of resistant bacteria:Already in the post war era of the later 1940s, first observations on growth promoting effects of antimicrobial substances were reported for swine and poultry. Antibiotics, such as streptomycin or sulphasuccidine, were said to increase both, feed utilization and growth rate, whilst simultaneously decreasing animals’ mortality. Although not fully understood, the most important mode of action of AGPs seems to be the reduction of microbial metabolic activity in the gastrointestinal tract of target animals avoiding sub-clinical infections and also diminishes the competition for nutrients. The reduced exposure to harmful bacteria or their toxic and growth depressing metabolic products is paralleled by anatomical changes in the gut. Hence, the use of antibiotics is related to an establishment of thinner intestinal villi and reduced gut walls, both as a proof of enhanced nutrient digestibility. Also anti-inflammatory effects result in reduced metabolic costs of the immune system.
Nevertheless, besides these benefits arising from AGP use, severe negative consequences come along with a widespread and non-specific intake of antimicrobial drugs. Actually, in the 1950s – only few years after the discovery of growth promoting effects of antibiotics – first reports on resistances in food animals came up. Today, the rate of establishing resistances increases above an unnatural level. As a result, antibacterial drugs have become less effective or even ineffective with negative impacts not only for industrial agriculture, but also for human medicine. A recent report from the World Health Organization warns that many infectious diseases may soon be untreatable due to antimicrobial resistance (AMR), and that antibiotic failure will convert minor community and hospital problems into fatal diseases.
Going away from AGPs
However, by focusing on the essential short-term effect of a fast growing livestock, the management of long-term consequences on animal and human health in view of in-feed antibiotics was underestimated over years. In the last decades a rethinking is taking place and with an increasing consumers’ demand for only safe products to appear in the food-chain, highest authorities of several countries counteract the use of antibiotics in sub-therapeutic quantities. In 2006, the European Union initiated the ban on the use of growth promoting in-feed antibiotics in animal production for reasons of antimicrobial resistance. Currently this prohibition is gradually spreading to other countries worldwide, with the USA restricting the use of antibiotic growth promoters by 2017. Nevertheless, by today there is no sufficient solution to counteract fully the production losses arising when omitting in-feed antibiotics. It is likely that countries, which have modern production systems applying good hygiene and production practices would also see limited productivity and economic effect of phasing out AGPs. However, countries with less optimized production systems could observe larger productivity effects and as a consequence larger economic effects. Anyhow, it is worth to say that negative consequences on production level are present in increased feed conversion ratio of about 1% and a strongly reduced weight gain of -2.7% in broilers and from -2.6% (weaners) to -6% (finishers) in pigs. Addressing the question what to use instead of AGPs, the most promising approach is rather to combine different strategies than solely trusting to find one ‘silver bullet’. In this manner first of all improvements in the animal management and highest hygiene standards should be established. This represents the basics to optimize further a farm’s profitability with the help of nutritional performance enhancers.
The natural and safe path
Research on alternatives like phytogenic feed additives has become prevalent to develop alternatives to in-feed antibiotics, as demanded by consumers and by legislation. When it comes to antibiotic-free animal production, nutritionists, veterinarians and animal producers often pursue a diet composition including phytogenic feed additives, a term coined by Delacon, in order to support the intestinal health of the animal. The wide range of modes of action of phytogenic additives can optimize nutrient digestibility and support the intestinal health.
Generally speaking, phytogenic feed additives represent powdery or liquid products to be mixed into compound feed of diverse livestock animals ranging from ruminants to monogastrics, such as poultry and swine. Phytogenics are characterized by their plant-derived origin and thus being natural and proven to be safe. Phytogenic feed additives consist mainly of essential oils, bitter and pungent substances, saponins, flavonoids, mucilages and tannins, it is evident that they are not only for sensorial stimulation but are also effective and potent in influencing the physiology in various species on various levels: Phytogenics are potent to improve nutrient utilization, stimulate enzymatic acitivity and even show anti-bacterial and anti-infammatory effects. Although, phytogenics and especially essential oils are demonstrated to come up with direct anti-bacterial effects, but occurring only at high concentrations and thus are unattractive to be processed into commercial feed additives for economic and/or sensorial reasons. Nevertheless, even in small amounts various plant-derived essential oils effectively interfere with a regulation system of bacteria, the so-called Quorum Sensing, which is crucial for the formation of a stable biofilm and hence, represents an essential factor in the infection process of pathogenic bacteria. Thus, these phytogenic components are potent to disturb the adhesion and colonization of pathogens via their anti-quorum sensing effects even in a low concentration, which can be used for feed additive production and which would not show any direct bactericidal consequences.
In view of this wide spectrum of different modes of actions, phytogenic feed additives using plant extracts are more effective compared to chemical nature-identical substances. This advantage is based on the synergistic effects of all agents within a plant, which have not been reduced to the effects of a single lead substance. Hence, an elaborated blend of different phytogenic components results in highly powerful natural feed additives, which are – together with highest standards in hygiene and livestock management – a promising solution supporting to compensate the consequences of withdrawing antibiotic growth promoters.
References upon request
*Delacon is the manufacturer of phytogenic feed additives.

by Dr. Stefan Hirtenlehner, Delacon