EVALUATION OF LOCALLY SOURCED FEED INGREDIENTS FOR PACIFIC WHITE SHRIMP Litopenaeus vannamei  

The rising costs of feed transportation have affected the productivity of shrimp farms in Hawaii and other remote islands. However, there are many tropical algal, agricultural and fishery by-products available in these areas, such as defatted Haematococcus (DH), Republic of the Marshall Islands (RMI) fish meal, and copra meal. These ingredients can be used to locally produce cost-effective aquatic feeds. The goal of this study was to evaluate the effects of several diets incorporating local ingredients on the growth performance and nutritional composition of Pacific white shrimp (Litopenaeus vannamei). These ingredients were selected based on their local abundance and cost.

Four diets were processed using a triple-pass method: a control diet (D-1), and the D-1 formula incorporating RMI fishmeal (D-2), defatted Haematococcus (D-3), and copra meal (D-4). Two diets (D-5, D-6) were processed with a modified steamless pelleting method using the same ingredient formulas as D-1 and D-3, respectively. Pellets of all diets went through heat-drying treatment (75 ^°C, 8 min). A commercial feed (D-7) was also used as a reference diet in the test. Each of the seven diets had three repetitive tanks (150L) and each tank was stocked with 12 juvenile shrimp and supplied with air stones and flow-through seawater at 25°C. After the 8 week indoor feeding trial, D-6 achieved significantly the highest weight gain (13.14 g), growth rate (1.64 g/wk) and specific growth rate (2.65 %/day) as shown in Table 1. This suggests that the diet which incorporated defatted Haematococcus and was processed by the modified method showed the best shrimp growth performance. The defatted Haematococcus diet also obtained significantly higher growth rates than commercial feed, although it contained lower amounts of  crude protein (34%) and  crude lipid (8%) than commercial feed (40% crude protein, 9% crude lipid). The defatted Haematococcus is a microalgae byproduct containing 40% to 42% crude protein with balanced amino acid profiles for the shrimp. Diets processed with the modified method (D-5, D-6) had similar or higher effects on shrimp growth performance as triple-pass method-processed diets (D-1, D-3). The modified method is a simple, quick, low-cost feed pelleting method. This study also analyzed proximate content, amino acid and fatty acid profiles for the tested diets and shrimp meat products.

These results indicate that the local defatted Haemattococcus and RMI fishmeal could be used as protein ingredients to produce cost-effective aquatic feed.