Optimum crude protein levels for high saline tiger shrimp farming
The effect of crude protein level on growth and protein utilization was studied in the juveniles of tiger shrimp Penaeus monodon in high saline conditions. The experiment was conducted with 2.5 g size animals at 40 ppt salinity for period of 6 weeks with four dietary crude protein levels of 40, 33.5, 27.3 and 23%. The experimental animals were acclimatized by changing 2 ‰ per day using crude common salt obtained from Kelambakkam salt pans. Signifi cantly (P<0.05) high growth rates were observed at 40 and 33.5% dietary crude protein levels. At 33.5% crude protein, signifi cantly (P<0.05) better Protein Effi ciency Ratio (PER) and Apparent Protein tilization (ATU%) were observed. The Free Amino Acid (FAA) levels of non-essential amino acids both in haemolymph and muscle was not signifi cantly different across all the treatments whereas the essential FAA levels were higher at 33.5% CP fed shrimp both in haemolymph and muscle. Haemolymph ammonia and urea N levels were highest at 40% CP fed shrimp indicating that the shrimps are under stress. Based on these results it can be concluded that at high salinity (40%), protein utilization effi ciency was better at 33.5% dietary protein level.