The Addition of Immunostimulant in Self-Formulated Feed to Improve Immunity and Growth of Juvenile Cobia (Rachycentron canadum)

Abstract

The aims of the experiment were to determine optimum dietary immunostimulant level in self-formulated on nonspecific immune response and growth performance of juvenile cobia fish. Fish were kept in net cages (0.8 x 0.8 x 0.6 m³) installed in fiberglass tanks which were completed with aeration and flow-through water system for 30 days. Design of the study was completely randomized design with 4 treatments, each consisting of 3 replications. Initial density was 50 fish for each replication with average body weight 4.69 g. the self-formulated feed (crude protein 46% and lipid 9%) containing three levels of immunostimulant additional levels, namely A (0.3%), B (0.5%), and as control, K (commercial feed as first control) and M (0.0% as second control without added immunostimulant. The data observed were growth performance which were consisted of absolute weight, total feed consumption, survival rate, specific growth rate, feed conversion rate and protein retention and mortality rate after challenge test with LD50 (1.0 x 10⁹ CFU/ml) of pathogenic bacteria Vibrio alginolyticus. The growth performances showed that fish fed with addition of immunostimulant 0,3% (A) obtained higher absolute weight values and significantly different (p<0,05) from M, but not significantly different from K. Challenge test at the end of the study showed that treatment A had lower mortality compared to other treatments which was indicated had higher immunity level compare to other treatments. Based on the results above, it can be concluded that the self-formulated feed with added immunostimulant 0.3% (0.7% total in the feed) showed the survival rate and optimal growth performance of juvenile cobia.