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¹ Guangdong Ocean University, Fisheries College, Zhanjiang, Guangdong, PR China DOI : 10.4194/1303-2712-v18_1_05 Viewed : 6476 - Downloaded : 4612 Based on restricted maximum likelihood (REML) method under animal model, the genetic parameters in Litopenaeus vannamei for growth-related traits on body weight (BW, g), body length (BL, cm), abdominal segment length (ASL, cm), carapace length (CL, cm), and survival (SU) under conditions of 96 hours of ammonia exposure at 14 and 21 weeks of age were estimated, respectively. The heritability estimates for growth-related traits at different growth stages were moderate, ranging from 0.24±0.09 to 0.30±0.06 for 14-week-old shrimp and 0.26±0.07 to 0.31±0.06 for 21-week-old shrimp, respectively. The heritability estimates for survival under conditions of high Ammonia-N concentrations were 0.13±0.11 for 14-week-old shrimp and 0.17±0.08 for 21-week-old shrimp, respectively. Genetic correlations between growth-related traits within age cohorts were generally high (ranging from 0.74±0.06 to 0.89±0.16), but for growth-related traits between ages were low (ranging from 0.14±0.05 to 0.46±0.09); genetic correlations between growth-related traits and survival under conditions of high Ammonia-N concentrations were all positive (ranging from 0.25±0.03 to 0.32±0.05). Our results suggest that selection to improve any single body trait would likely produce correlated responses in the other traits examined and that selecting for growth will cause a positive correlated response in terms of Ammonia-N tolerance; estimates of genetic parameters for Ammonia-N tolerance should be calculated at a later age. Keywords : Litopenaeus vannamei, growth-related traits, Ammonia-N tolerance, heritability, genetic correlation