INTERACTIVE EFFECTS OF DIETARY PROTEIN LEVELS AND PROTEIN QUALITY ON GROWTH PERFORMANCE OF MALAYSIAN PRAWN, Macrobrachium rosenbergii

A feeding trial was designed to determine the effects of dietary protein levels and dietary fishmeal (FM) replacement levels; and the interaction between them on growth performance and feed utilization of freshwater prawn. This experiment was conducted in 2 factorial design. Macrobrachium rosenbergii post larvae culture in tank 100L (fill with 80L) for 50 days. The experimental treatments were assigned in triplicates. Six test diets were formulated to contain two different protein levels (P35% and P40%) and three levels of FM replacement (FM0%, FM35%, FM70%). The dietary FM was replaced with a blend of palm kernel meal (PKM) and fish bone meal (FBM). The diets were designated as Diet 1 (P35 FM0), Diet 2 (P35 FM35), Diet 3 (P35 FM70), Diet 4 (P40 FM0), Diet 5 (P40 FM35) and Diet 6 (P40 FM70), respectively. Result of the present study indicated that both dietary protein levels and FM replacement levels had significant (P<0.05) effects on growth performance and feed conversion ratio, while no interaction was found between the two factors on the analyzed parameters. Increasing dietary protein from 35% to 40% increased the growth performance of prawn. On the contrary, replacement of FM significantly decreased the growth performance of prawn. The freshwater prawn fed Diet 4 (P40 FM0) showed significantly highest growth performance, while the lowest was found in prawn fed Diet 3 (P35 FM70). On the other hand, survival rate was not significantly varied among the treatments. The highest level of PKM & FBM (70%) inclusion in diets gave significantly lower growth performance and nutrient utilization of M.rosenbergii in both dietary protein levels. However, differences were not found in the performance of prawn fed Diet1 (P35 FM0) and Diet 6 (P40 FM70). Similar results were evident for feed intake and protein efficiency ratio. Therefore, the present study concluded that at 35% dietary protein level, a mixture of fish bone meal and palm kernel meal could replace up to 35% FM and increasing dietary protein to 40% could replace up to 70% fishmeal with the blend of PKM and FBM. Therefore, PKM and FBM are proven potential alternative protein sources which could replace a significant portion of fishmeal protein in aquafeeds. Fishmeal replacement levels could be further improved by increasing 5% dietary crude protein.