Influence of Phytogenic Feed Additives on The Health Status in The Gut and Disease Resistance of Cultured Fish

Abstract

Phytogenics are plant-derived natural compounds in the diets that aim to improve animal production. Several of these plant-derived substances have been tested in various aquaculture fish species particularly on their effects on growth and systemic immune response. Most of the previous studies demonstrated positive effects in improving growth, lowering the feed conversion ratio (FCR) and modulating the various immune response parameters in fish. While nutritional strategies are mostly designed towards the use of plant-based materials as feed ingredients or partial substitutions for the more expensive fish meal in the fish diets, recent initiatives have been targeting the use of these phytogenics as feed additives. The tissues and organs of the digestive system are the ones that have close contact with the phytogenic additives once these are ingested by the fish. Once, digested and absorbed, these substances are distributed throughout the body where they affect the physiological conditions of the fish, including its ability to provide resistance against various infectious diseases. The present work provides a short review on the effects during dietary administration with these phytogenics on gut health and disease resistance in fish. A synthesis of available information on these biological aspects in fish will provide a platform towards developing functional feeds in aquaculture.