Improving feeds and feeding for small scale aquaculture in Vietnam and Cambodia

• Can Tho University, Vietnam
• Royal University of Agriculture, Cambodia
• Lake Argyle Industries Pty Ltd, Australia
• Research Institute for Aquaculture No. 1, Vietnam
• Aquaservice, Vietnam

Aquaculture, or fish farming, is the fastest growing food production sector in the world. It is being seen as a sustainable solution to the growing pressure that increased fishing activities are placing on wild resources. Advances in culturing fish are reducing the capture of wild juvenile fish, to then grow to size, boosting the value of fish farming. But further advances are needed to ensure aquaculture itself remains a viable and sustainable option for smallholders and the environment alike. One component where advances could enhance sustainability is in fish diets. Most fish farmers do not buy commercial feeds. The high cost of these are not adequately returned in the market price of fish. Farmers make their own feeds using available ingredients, such as rice bran and trash fish. Often these formulations do not sufficiently meet the nutritional needs of growing juvenile fish. To compensate some farmers ensure excess food and nutrients are available, eating into profit margins and increasing the likelihood of environmental impacts.

In Vietnam and Cambodia smallholder farmers are keen to get involved in aquaculture. The main barrier is a lack of information on the ingredients for diets. This, when assessed against the nutritional needs of fish species farmed, can help in formulating optimal diets. Differences in feed requirements also extend to the stage of development; high protein and energy required in juvenile fish is not always suitable for maintaining health in fully grown fish. Bio-energetic modelling, using these variables, can define protein and energy requirements and then guide the formulation of diets using local ingredients to match these parameters.

The overall aim of the project is to enhance the development of sustainable aquaculture using locally (Vietnam/Cambodia) derived ingredients and better formulated feeds to:
develop diets based on locally-available ingredients for improved production of (Pangasius catfish and tilapia in southern Vietnam, Pangasius catfish in northern Vietnam and Cambodia and barramundi in Australia),
demonstrate/evaluate the potential of new improved feeds in on farm trials, and
transfer technology and extend information.

Objective 1
a prospective inventory of locally available ingredients with feed potential prepared
survey and collection of samples and supply data
identification of best ingredients to use and evaluation using digestibility assessment methods for catfish and tilapia
d etermination of the efficiencies of protein and energy use
diets for tilapia defined using existing specifications and digestible nutrient data of key ingredients
refined bio-energetic model for barramundi defined

Objective 2
laboratory validation trials of new improved feeds
on-farm validation trials of new improved feeds
assessment of the economic impact of existing farm practices and feed use and of altering feed use from traditional to progressively more complete feeds

Objective 3
workshops held for extension officers and farmers
NGO's trained to help extend results to farmers
extension officers attached to both the Ministry of Fisheries and the commune system in Vietnam approached to participate in extension workshops and supported where possible to transfer results as widely as possible

The project achieved its primary objectives, with progress being excellent in the Mekong Delta (the main focus of the project). Progress in northern Vietnam was good but delayed by project staff changes. In Cambodia progress was mainly related to capacity building.
The project sought to develop diets based on locally available ingredients for improved production of Pangasius catfish and tilapia in southern Vietnam, Pangasius catfish in northern Vietnam and Cambodia, and barramundi in Australia. The project team collected regional and seasonal information on the availability and nutrient composition of local feed ingredients, which included trash fish and commercial grain products. These data are being compiled into a database that will be published, either in print or on the Internet, to make it as widely available as possible to potential users.
Formulation of efficient and cost-effective diets for the fish species of interest was through the development of a bio-energetic model for each species, to relate protein and energy requirements to size of fish and water temperature during culture. The model requires data from a complex series of experiments for each species. Together with information on the nutritional value of locally available ingredients, this model can be used to assist in the formulation of feeds and the feeding strategy for the particular feeds. This work progressed extremely well with outstanding results for barramundi and catfish. Good results were also obtained for tilapia but these will require further refinement.
The Principal Investigator interacted closely with the Australian barramundi farming industry to pass on the information on the project's barramundi bio-energetic model. New diet formulations for barramundi, based on the model have been produced, tested and adopted by commercial feed manufacturers in Australia.
Diets for catfish and tilapia that were formulated and produced at RIA1 in Vietnam were assessed on a number of small farms. The on-farm trials were used to compare locally prepared (on-farm) feeds with the feeds produced at RIA1.
The economic benefit of these diets is still being assessed. The main constraints to increasing use of formulated feeds to replace low-value fish as feeds for key species in Vietnam (other than Pangasius catfish production in the Mekong Delta) are the lack of information to demonstrate the cost-effectiveness of formulated feeds in comparison to trash fish, lack of the information needed to formulate cost-effective feeds, the perceived high price of currently-available formulated feeds relative to trash fish, and lack of a compelling argument to encourage the support and commitment of feed companies to manufacture the feed once a formulation is developed.
Future priority research initiatives to address these constraints are associated with the development of cost-effective feeds. Priorities include understanding the production status and potential demand for feed for target species, current status and use of trash fish and barriers to changing practice, better understanding of the nutritional requirements of target species, evaluation of the potential of available ingredients for use in formulated feeds, understanding of how feeding strategies need to change to adapt to formulated feeds, finally overcoming the barriers for feed companies to manufacture formulated feeds and for farmers to use these feeds.