NUTRITIONAL EVALUATION ON LOCAL FEED INGREDIENTS FOR TILAPIA (O. Hornorum) PRODUCTION IN HAWAII

Aquaculture in Hawaii and other Pacific regions relies heavily on imported ingredients and feeds. The rising costs for transportation and the unstable supplies of imported feeds become one of the major concerns for a profitable aquaculture in these regions. Thus this study was aimed to develop a local feed for tilapia production in Hawaii.

Local feed ingredients or coproducts including a fish meal, copra meal, microalgae meals, black soldier fly pupae meal, cassava, wheat mill bran, and breadfruit were analyzed for their proximate composition, minerals, and amino acids. Fatty acid compositions of macadamia oil and black soldier fly meal were determined compared with the compositions of menhaden and soybean oil.  Selected ingredients were determined for apparent digestibility coefficient (ADC) of protein and dry matter and then used to formulate a local feed for tilapia (Oreochromis U. Hornorum).  Results of this study showed that the ADC of dry matter for the local fish meal, spirulina, and cassava were similar to the dry matter ADC of menhaden fishmeal (P≥0.05).  Haematoccus, wheat mill bran, black soldier fly meal, and copra meal were shown to have a lower value of ADC than menhaden fishmeal (P<0.05).

A 6-week of feeding trial was conducted to feed juvenile tilapia (average body weight, 9.5 g) raised indoor with test diets including different local ingredients.  Nutritional potential of test diets were evaluated based on growth performance (specific growth rate, feed conversion ratio, protein efficiency ratio, hepatosomatic index and carcass index) and proximate nutritional composition (protein, lipid, ash and moisture) carcass. No significant impairment was found on fish with the replacement of menhaden fishmeal, wheat flour and corn meal by the local fishmeal, wheat meal bran and copra meal. A feed being formulated with local ingredients (fish meal, haematococcus, wheat meal bran, cassava, and copra meal) to replace up to 94% of imported ingredients did not caused any adverse effect on the growth performance and all the nutrient compositions of carcass except for a lower lipid level in the carcass of tilapia.  Furthermore, replacement of canola oil with macadamia oil did not influence the growth performance and nutritional composition of the tilapia.

The results of this study demonstrated the significant potential of local feed production in Hawaii from a nutritional point view. Results based on a long term feeding will be needed to confirm this finding.  A comprehensive economic analysis on local feed production is also recommended for future research.