Monday, November 16, 2015

Plant Extracts in Aquaculture Feeds: From Modes of Action to Practical Application

Clementine Oguey, Aqua Product Expert, PANCOSMA & Associates

The term plant extracts usually refers to components naturally occurring in plants, and namely regroups true plant extract such as essential oils or oleoresins, and nature identical molecules. These additives commonly suffer from a lack of transparency in the commercially available products and an inconsistency in their contents in active molecules, explaining the great discrepancy of activity between products containing similar compounds. However, as long as the additives considered have standardized formula and manufacturing process, their mode of action at recommended dosage can be consistently elucidated. This consequently explains the beneficial effects of these products on performance and health.
Historically, the effect of plant extracts is based on their antimicrobial activity. The minimum inhibitory concentrations of these compounds remain much higher than the standard dosages recommended in animal diets. This suggests that the effect of these products is not associated to a direct antimicrobial activity and highlights the importance to test them at their recommended dosage.
Well defined plant extracts such as standardized capsicum, turmeric oleoresins or cinnamaldehyde have been shown to modulate immunity at reduced levels and affected the systemic immune response of animals challenged with bacteria or viruses. The clarification of the mode of action of single plant extract associated to comparative physiology enable to develop combinations targeting specific applications.
Under standard animal production practices, the beneficial impact of these plant extracts on gut immune modulation can explain their efficacy to consistently improve gut function and subsequent fish resistance to disease and performance.
Plant extracts generally suffer from a lack of consistency to improve productive performance of target species. Consecutive trials demonstrated that compared to a negative control, a blend of three specific phytocomponents consistently increased body weight gain by and reduced feed conversion ratio in tilapia.
In addition to this beneficial impact on productive performance, the gut immunity effect of some plant extracts can also be exploited to increase the resistance of aqua species to diseases induced for example by bacteria.
Despite common belief, well defined and standardized plant extracts based feed additives are good tools to improve health and performance in current aqua production systems. The extended knowledge of the primary effects of these compounds opens new fields of utilization. However, the nutritional application of such products also involves taking into account gut physiology, immunology and microbiology, and farm practices.

Clementine Oguey received her B.S. degree in animal nutrition, and M.S. degree in Agro-food and health from ISAB, a French university specializing in agricultural engineering. Following her graduation in 2006, she joined Pancosam's R&D department in Geneva, Switzerland, where she currently works as a Technical Expert, focusing on the XTRACT® range of plant extract-based products, for all animals, including aquatic species. Her role is to coordinate all field trials worldwide, to provide technical support, as well as to publish scientific articles and participate in international conferences. She has been working on the practical application of plant extract based feed additives in aqua species for three years.

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