Development of Innovative Feed Products and Feed Concepts for Marine Species in Aquaculture

The sustainability challenges of the aquaculture sector will probably be closely linked with continuing interest in ingredients as alternatives to fishmeal for use within aquafeeds. Among the many protein sources available, plant proteins appear to be the most appropriate alternatives. Different aspects on the health implications of using vegetable feed ingredients on the digestive tract, plus possible effects on quality of the fish, are some of the most relevant problems currently confronting the aqua industry. The need to understand this phenomenon leads to the present thesis, in which the investigation on the feasibility of the inclusion of plant protein in aquafeed was undertaken through a multidisciplinary approach. The first study highlighted that inclusion of soybean meal in combination with different blends of plant protein maintains optimal growth in 20% fish meal dietary level for the on-growing of European sea bass. Despite fiber is considered as a component that cannot be utilized by most fish, inclusion up to 9.3% has no effects on growth, feed efficiency and digesta transit time in European sea bass. It was encouraging to note that inclusion of high levels of plant protein sources and fiber did not affect health and nutritional status of the animals. When replacing fish meal in aquafeeds, besides the research on alternative ingredients, also the nutritional profile should be considered. In the third study, it was demonstrated that taurine is a required nutrient for juvenile Southern flounder. The fourth study, highlighted that increasing the inclusion of plant ingredients, in substitution of fish meal, had no effects on quality traits of the commercial product. However, it is not yet an easy or economi¬cally feasible task to reduce the aquaculture dependence from marine feedstuff, the present thesis has contributed to provide some insights on the feasibility of the replacement of fish meal in aquafeed.