Effect of Protein Quality on Optimal Daily Protein Supply for Juvenile of Patin (Pangasianodon hypophthalmus)

Abstract

Two types of diet with different protein quality were formulated, namely High Fish Meal (HFM with 46.8 g CP kg-1) and Low Fish Meal (LFM with 46.3 g CP kg-1). Feeding rates were calculated to provide six different protein supplies 8, 14, 20, 23, 26, and 30 g kg-1 day-1 to duplicate groups of fish. Fishes were 3-inch length with an average mass 6.4±0.2 g. The density was 12 fish per aquarium. Daily ration was given in the 3 equal meals at 08.00, 12.00 and 16.00 for 6 weeks. Amino acid profiles show that HFM diet fulfilled requirement according to recommendations for channel catfish, while LFM diet appeared deficient in lysine. The specific growth rate, food conversion ratio, body fat, protein retention, fat retention and protein efficiency ratio were significantly different among treatments. On contrary, dry matter, protein, ash, gross energy did not differ significantly between treatments. Both dry matter and protein digestibility led to similar values for the two diets. Regarding response to protein supply, the results indicated that higher protein supply was required to reach maximum growth with LFM (17.8 g kg-1 day-1 for 2.04% day-1) than with HFM (16.1 g kg-1 day-1 for 2.5% day-1) diet. This suggests that increase in protein supply may partially compensate lower growth with lower dietary protein quality.