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Figure 5: Quantification of microbial classes in ileum and caecum of broilers fed the phytogenic product, relative to their abundance in control birds (set at 100%, blue dashed line). A low ratio of total bacteria and Enterobacteriaceae over lactobacilli in the ileum is generally regarded as reflecting a healthy microbial balance. In the caeca, a rich microbial population, with a substantial population of butyrate-producing bacteria, is seen as beneficial.


Figure 6: Broilers supplemented with the phytogenic product (green) outperform birds from the negative control group (grey) in average daily weight gain (ADWG), final weight and FCR, corrected at 1500 g (FCR-1500)


C. elegans worms were grown on medium, in presence or absence


of Salmonella, and with or without supplementation of the botanical extract under study. We observed that the botanical prototype, when supplemented at low concentrations that did not affect Salmonella growth, was able to significantly increase survival of the roundworms. Given that that the mortality resulting from Salmonella infection is QS- dependent, and that the botanical prototype is capable of inhibiting QS in vitro, it can be hypothesized that this result can be explained by the QS inhibiting effect of the prototype.


Effect on gut health and performance Subsequently, field trials were set up to evaluate the effect of supplementing broilers with the botanical prototype. The microbial composition of birds fed the phytogenic product shifted toward a profile that is typically associated with an increased gut health (Figure 5). In line with that, their zootechnical performance was better than that of control birds (Figure 6).


Conclusion Intestinal bacteria are of vital importance to the wellbeing and performance of production animals. Several feed additives, including


botanical products, have therefore been commercialized to modulate gut microbial bacteria and to support intestinal health. In vitro tests are valuable tools to develop such botanical products.


Apart from screening for bacteriostatic effects, it can be argued that biological activities playing a role at much lower concentrations, such as the modulation of gut bacterial QS, should be considered. The experiments described above demonstrate that QS assays


can be used to develop a phytogenic feed additives, which in subsequent analyses has been shown to improve gut health parameters and animal performance. The importance of QS in production animals is currently not


fully clear and the potential and consequences of inhibiting QS in the digestive tract remain to be further investigated. However, it is important that the effects that botanical substances can exert at low concentrations are explored; as such, QS is a potential promising tool to be considered for such investigations.


This article is based on the text of a paper presented by Dr Goossens at the recent Society of Feed Technologists Poultry meeting


FEED COMPOUNDER MARCH/APRIL 2017 PAGE 47


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