The expansion of cage aquaculture, particularly for Asian seabass (Lates calcarifer), in Cambodia is increasing the demand for low-value ‘trash’ fish and fishmeal as feed sources. The negative aspects of using ‘trash’ fish as an aquafeed are well documented, and in Cambodia the cost of ‘trash’ fish is increasing year by year because of increasing demand. To reduce feed costs and increase sustainability of cage aquaculture, we have been evaluating the availability of local feed ingredients that can be used for compounded aquafeeds.
To determine the availability of feed ingredients, we surveyed several sources in Preah Sihanouk province. Maximum availability of fishmeal is 216 tonnes per month from April to May which is the period of peak catches, and minimum availability is about 180 tonnes from October to November when catches decline because of the rainy season. The availability of squid followed a similar pattern with peak catches, and availability, in April, and minimum availability in October. In addition, the Angkor beer factories in Preah Sihanouk province produce fermented brewery yeast as a waste product, with 9–13 tonnes available monthly. Other potential ingredients that are readily available include rice bran, soybean, Leucaena leaf, and Moringa leaf.
Proximate analysis of a sub-set of ingredients was carried out according to AOAC (1999) methods to provide data for feed formulation (Table 1). Future research will focus on developing feeds for Asian seabass that incorporate local ingredients. In particular, we are evaluating the use of brewery yeast as a protein source to reduce the proportion of fishmeal in diets for Asian seabass.