Southern Bluefin Tuna Aquaculture Subprogram Project 2: development and optimisation of manufactured feeds for farmed southern bluefin tuna
SARDI Food Safety and Innovation
Robert van Barneveld
At present the tuna farming industry is almost entirely dependent on whole defrosted pilchards as a feed, with about 50% of the 15 - 20 thousand tonnes used in 1994/95 sourced overseas. The development of a suitable manufactured feed is a high priority with industry and government because: a) international supplies of pilchards are variable in volume and quality (eg. Japanese supplies have declined markedly and the fat content of pilchards used in feeds varies from 1 - 22%); b) manufactured diets will provide the potential for improved product quality (in particular fat content, colour and texture) as they are more stable in storage than pilchards and can be altered to better meet the requirements of fish farming and the markets; c) manufactured diets will reduce industry feeding costs as their generally lesser moisture content and better feed conversion ratio will reduce the quantities required and therefore costs associated with feed storage and transport; d) manufactured diets will greatly reduce environmental concerns associated with the present use of pilchards, including: reducing the overall requirement for pilchards, minimising risks of importing and dispersing undesirable diseases and pests, and reducing organic wastes in the farm environment which can harbor and promote diseases as well as detrimentally effect water quality. The development of manufactured diets has been clearly recognised as a high priority by the Tuna Boat Owners Association of Australia (TBOAA) (numerous scientific workshops), the CRC for Aquaculture (Tuna Research Review Task Force) and the national Task Force on the Importation of Fish and Fish Products. Participating feed companies are also supportitive as they will benefit from the desired outcome. The economic benefits of the development of a suitable formulated feed has been estimated (see B6 - Benefits and Beneficiaries) to be as high as $9.5 million/annum to the TBOAA and $5 million to successful feed manufacturers. Additional economic benefits would be expected to flow from ongoing research leading to further enhancements of feeds.
1. Develop a cost-effective, sustainable manufactured diet for farmed SBT that contains reduced levels of fish meal, trash fish and fish oils while maintaining growth performance and flesh characteristics.
2. Assess the response of farmed SBT to changes in diet moisture and protein content.
3. Assess the influence of artificial colour enhancers on the flesh characteristics of farmed SBT.
4. Identify extrusion techniques that will produce a cost-effectice, acceptable manufactured feed for farmed SBT.
5. To determine the efficiency of digestion of farmed SBT fed manufactured diets
6. Improve our understanding of the physiological responses by farmed SBT to manufactured diets.
7. Reduce nutrient excretion through improved knowledge of the nutritional value of diet ingredients for farmed SBT.
Principal Investigator: Dr R.J. van Barneveld, Dr C.G. Carter, Dr B.D. Glencross & Mr S.M. Clarke