ISSUE FOCUS FEED & ADDITIVE MAGAZINE March 2022 41 Most of these classes are summarized by the scientific term “secondary plant products,” referring to substances produced by a plant in relatively small amounts related to survival strategies. They are used as a defense against herbivorous, to prevent some parasites, or to attract pollinators by producing a particular smell or causing a typical plant color. Thus, although they are not directly needed for the plant's survival like primary products (carbohydrates, proteins, vitamins…), secondary plant products can have a crucial impact on its lifespan. When taken up by livestock, they may influence the animal's physiology and improve milk production. A single plant can produce different types of extracts or substances. The composition of active ingredients of a plant can vary depending on the type of extract, the weather conditions under which it developed, the geographical origin, or even its subspecies and cultivars. On the other hand, a given active component can be found in different plants (like thymol, found in thyme and oregano, for instance), making the supply of that substance more flexible. Therefore, when formulating a PFA, it is better not to refer to the amount of plant extract itself but consider the concentration of active ingredients inside. To do so, some lead substances are identified as the active components selected to obtain the desired mode of action of the product. They are analyzed and dosed in the different raw materials used to formulate the PFA, to guarantee the consistency of the final product batch, independently of the plant's origin. ACTIVE INGREDIENTS AND TECHNOLOGY TO IMPROVE AVAILABILITY Based on the extraction methodology, the active components differ. For instance, if we consider spices, it is possible to extract oleoresins or essential oils (EOs). Oleoresins are a natural mixture of EOs and resin extracted from the plant source by solvent extraction, whereas EOs result from steam distillation since they are not miscible with water. They can then be analyzed by spectrometry to determine the different lead substances composing them to ensure the final PFA's expected composition will be met. Saponins are another example: depending on the part of the plant they are originating (bark, root, seeds, etc.), the extraction method is different, as is the mix and concentration obtained of the various saponins. To quantify the effect of the resulting saponin extracts, some such as the HPLCmethodology can be performed.
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