Growth Performance of Giant Freshwater Prawn (Macrobrachium rosenbergii) Fed with Supplementary Diets Containing Varying Levels of Shrimp Processing Discards

Abstract

The growth performance of giant freshwater prawns (Macrobrachium rosenbergii) was observed using four experimental diets. Prawn juveniles, approximately weighing 1.5 g, were reared for 93 days in 8 mini ponds at a stocking density of 3 prawns/m². Feeds were prepared using similar amounts of locally available indigenous feed ingredients with varying levels of shrimp processing discards (shrimp meal) and fish meal so as to obtain approximately 25% dietary protein on a dry weight basis. Feed-1, designated as the control, contained 100% fish meal. Feed-2 contained 75% fish meal and 25% shrimp meal, and Feed-3 contained 50% fish meal and 50% shrimp meal, whereas Feed-4 was prepared with 100% shrimp meal. The water quality of the experimental ponds was monitored and found to be within the acceptable limits. Initially, feeds were supplied at a rate of 10% of the body weight of prawns twice a day, followed by feeding at satiation level, as determined with the help of feed trays. The highest and lowest weight gains were observed for Feed-2 (22.85 ± 0.19 g) and Feed-3 (18.33 ± 0.11 g), respectively. There was a significant difference (P < 0.05) among the treatments. The specific growth rate of prawns ranged from 2.51 ± 0.04 to 2.87 ± 0.09 in Feed-4 and Feed-2, respectively. The mean feed conversion ratio varied between 2.26 ± 0.20 (Feed-2) and 3.33 ± 0.03 (Feed-4). The highest protein efficiency ratio was found in Feed-2 (1.71 ± 0.15), while the lowest was found in Feed-4 (1.16 ± 0.09). There was no significant difference (P > 0.05) in the various growth parameters among the treatments; however, Feed-2 apparently indicated the best growth performance compared with the control and other feeds. Muscle composition was examined after harvesting. The highest protein content of body flesh was found in prawns fed Feed-3 (18.77 ± 1.39%), and the lowest was found in those fed Feed-4 (17.10 ± 0.28%). On the other hand, the highest protein content of head flesh was found in prawns fed Feed-1 (15.88 ± 0.17%), and the lowest was found in prawns receiving Feed-2 (13.21 ± 1.01%). In conclusion, a supplementary feed containing 25% shrimp meal could be used to obtain satisfactory production of M. rosenbergii.