Effects of inulin and Jerusalem artichoke (Helianthus tuberosus) as prebiotic ingredients in the diet of juvenile Nile tilapia (Oreochromis niloticus)

Introduction

Tilapia production has increased intensely to meet the growing global demand for fishery products. In particular, production of Nile tilapia (Oreochromis niloticus) has commercially dominated the farm-raised tilapia industry. Although Nile tilapia are easy to culture and fast growing in tropical areas, mass death in tilapia farms due to outbreaks of disease occasionally occurs, particularly when the water temperature is high during summer. Chemotherapeutic agents such as antibiotics have been used to control the risk of disease in tilapia farms. However, the overuse of antibiotics in fish farms may pose a threat to public health and also adversely impact the ecosystem. Application of biotherapeutics such as prebiotics as an alternative to chemotherapy may prove to be an environmentally friendly tool for use in fish farming.

Prebiotics are defined as non-digestible food ingredients that beneficially affect host health by selectively stimulating the growth and/or activity of healthful bacteria and by combating undesired bacteria in the intestinal tract. Inulin, which belongs to a class of carbohydrates known as fructans, is one of the most common prebiotics used in feed for livestock and aquatic animals. Inulin is composed of fructosyl residues, which are linked by -2,1-linkages. In humans and monogastric animals, fructans generally cannot be hydrolysed by digestive enzymes in the proximal intestinal tract. Instead, they are fermented in the large intestine or colon by beneficial bifidobacteria and other lactic acid producing bacteria, thereby enhancing their relative populations. Several dietary grades of inulin are available commercially, and their use as a dietary supplement in animal feed has been shownto enhance growthperformance,modulate intestinalmicrobiota, andimprovehematological andimmuneparameters in fish, poultry, and swine. Nevertheless, the use of inulin as a functional feed additive in the animal feed industry is limited by the cost of the inulin extraction process. Therefore, finding eco-friendly sources of fructan-type functional feed ingredients would contribute greatly to aquaculture productivity.