and at higher dose biocide effects. Their anti-inflammatory, antioxidant, antimicrobial activities are now well documented. Like vitamins and trace elements, they contribute to the homeostatic balance and therefore to the maintenance of a good state of health (Figure 1). Besides, early researchers like Albert Szent-Györgyi (Nobel prize for the discover of vitamin C) proposed that flavonoids should be considered as vitamins. While nutritionists have considered the need for vitamins and trace elements in feed formulas for farm animals, how could we have forgotten these essential ingredients?
Plant extracts and essential oils In fact, when distributed to healthy animal at inappropriate level, most of the PSMs have so called “antinutritional” activities. They can reduce digestibility, some of them, because of their bitter taste, can decrease feed intake and at higher doses they become toxic. Furthermore, if we only focussed on nutritional requirements of healthy animals in healthy situations, PSMs distributed at high doses can reduce the growth and production of farm animals. The success of antibiotics in livestock production has probably something to do with the fact that we did not consider the need for these specific nutrients that are PSMs in livestock diets. In the 2000s, a lot of research on antibiotics used in animal production showed that, in addition to their antibacterial effects, they also had anti-inflammatory effects… like PSMs. In facts, antibiotics probably took the place that PSMs have in “natural nutrition”. Since then, working on plants parts providing PSMs or plant extracts and essential oils that concentrate them, has become an essential part of livestock nutrition research and diet formulation. Fred Provenza (professor emeritus of Behavioural Ecology at Utah State University) summarises this evolution as follows “The challenge of feeding systems is incorporating mixes of plants with bioactive properties in ways that enhance health and welfare without compromising production”. CCPA anticipated this challenge more than 20 years ago, working in three complementary directions: • Measure the biological activities of plants to screen plants and synergic associations of plants
• Characterise plants and their composition to ensure stable effects
• Evaluate in vivo the health, welfare and production bene- fits for livestock animals and farmers
We develop in vitro test to evaluate antimicrobial activities of PSMs and their effects on gut microbiota. Anti-inflammatory and antioxidant activities are screened with specific cells models (Figure 2).
Inspired by nature Working with the department of Hormonal and Nutritional Biochemistry of Grenoble Hospital and Dr Michel Brack, oxidative stress specialist, we developed the first oxidative
0.6 0.4 0.2 0 Control Plant 1 Plant 2 Plant 1 + 2 ▶ ANTIBIOTIC REDUCTION | DECEMBER 2021 55
stress diagnostic tool adapted to farm animals. Each year, around 20 in vivo trials are done in our research station Euronutrition or in collaboration with international research teams to define nutritional requirements for plants secondary metabolites in pigs, poultry and ruminants, as we do for all classical nutrients. Even if there is still a lot of research to do, this strategy inspired by nature turns out to be a success in many phases of breeding in reducing or stopping preventive use of antibiotics.
References available on request.
Figure 2 - In vitro inflammation marker (TNF α) expression under pro inflammatory condition (LPS model) with addition of standardised plant extracts (10 mg/ml). CCPA and Rennes 1 University.
1.2 1 0.8
Harnessing the power of nature can offer a solution to reducing the use of antibiotics in livestock.
PHOTO: SANDRA CUNNINGHAM Relative TNF α gene expression in Enterocyte cell model
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