Received: 03-08-2012 / Accepted: 25-09-2012
Litopenaeus vannamei) cultured in biosecurity system. Three groups of experimental shrimp (initial weigh 20.1±1.9 g/male and 21.4±2.2 g/female) were stocked at densityof10, 20 and 30 heads/m3in4m3indoor tank system. Each treatment was run in triplicate and fed with about 4% shrimp weight daily with pellet diets of CP 7704S and 7704P (38% crude protein), feeding four times a day. The water temperature ranged from 20.0 - 28.5oC and salinity ranged from 20-28‰. Water was renewed 80% volume weekly. The highest growth rate in weight was recorded in broodstock candidates cultured at 10 heads/m3(1.03 g/week/male; 1.11 g/week/female), followedby 20 heads/m3(0.89 g/week/male; 0.98g/week/female) and the least for 30 heads/m3(0.53 g/week/male; 0.62 g/week/female). Similarly, survival rate of shrimp at 10 heads/m3(71.7 ± 2.7%) ranked highest and the lowest rate for the 30 heads/m3 (60.1 ± 2.8%; P<0.05). Nevertheless, there is no significant difference in the survival rate between shrimp cultured at 10 heads/m3(71.7% ± 2.7%) and 20 heads/m3(71.5 ±3.0%; P>0.05). Size variation (CV%) and FCR recorded on 10 heads/m3 (CV%: 6.34 ± 1.12%; FCR: 2.78 ± 0.5) and 20 heads/m3(CV%: 6.68 ± 1.20%; FCR: 2.86 ± 0.3) were found remarkably lower than that for 30 heads/m3(CV%: 10.56 ±2.24%; FCR: 3.42 ± 0.8; P<0.05). The percentage ofshrimp harvested thatmet the criteria of broodstock was 67.1 ±2.6% and 66.7 ± 3.2% for the 10 and 20 heads/m3, respectively, whereasonly 23.1 ± 5.4% for the 30 heads/m3. All shrimp sample tissues were found negative for WSSV, YHV, TSV, MBVandIHHNV.