Development of supplemental diets for carp in Vietnamese upland ponds based on locally available resources

Introduction

Son La province is located in the mountainous region of North-Western Vietnam and is one of the poorest provinces in the country with about 54% of Black Thai ethnic minority. In this region, the production of fish in ponds is one of the most typical activities and contributes to household food security and income generation.

The typical pond system in the research area can be characterized by polyculture of grass carp, other carp species and tilapia and feeding of crop residues, including leaf material and grass. The productivity in this pond system is considered as low. Even though most of farmers around Yen Chau town own at least one pond, the demand on the local market cannot be met.

The feed currently applied is mainly consumed by the macro-herbivorous grass carp and only to small extends by other fish species. So far unknown diseases causing high mortalities limit the production of grass carp. To avoid risk of loosing fish, farmers tend to change the composition of the fish species stocked in favour of e.g. common and mud carp without having an appropriate feed base for these species.

While farmers usually sell cassava and maize to traders from lowlands, which often pay relatively low prices. If farmers could convert those crops into high-value fish, they would have the chance to participate in the value added marketable production chain. Furthermore, fish is well known as an important nutritional product for human consumption and contributes thereby to food security in the region.

Objectives

The overall aim is the development of a supplemental fish feed with a crude protein content of approximately 30%, which can be produced in a cheap and easy way by farmers themselves. This could contribute to the improvement of income and food security in the region.

The specific objectives are:

• Analyzing and testing available potential feed resources such as maize, cassava and soybean in order to assess their nutritional values.
• Developing and testing appropriate supplemental feeds for the non-grass-carp species in the pond system.

·        Finding out if the supplemental feeds influence on fish growth by providing not only the amount of essential amino acids, but also the non-essential amino acids. These are the most valuable components of the diet and should be used as efficiently as possible

Progress so far

Three different compound feeds with approximately 30% of crude protein were made up from cassava powder, maize powder, soy bean, rice bran and fish meal. Those feeds, together with standard feed as control, are currently being tested on common carp (Cyprinus carpio) in the recirculation system at Hohenheim University.