Genetic parameters and response to selection for harvest body weight of the giant freshwater prawn Macrobrachium rosenbergii

Genetic parameters and response to selection were estimated for harvest body weight of the giant freshwater prawn Macrobrachium rosenbergii using a fully pedigreed synthetic population from three introduced strains. The data included 65,917 progeny that were from 331 sires and 544 dams in five generations with a nested mating structure. Harvest body weight was transformed by square root for analysis. Variance components and genetic parameters were estimated using an animal model and the restricted maximum likelihood method. The estimated breeding values of all animals over five generations were calculated using best linear unbiased prediction. Within generations, the heritability estimates for harvest body weight in each generation ranged from low to moderate (0.055 +/- 0.012 to 0.223 +/- 0.045) and were significantly different from zero (P<0.05). Only the common environmental effect of the three generations from G1 to G3 could be estimated, which was found to vary from 0.024 +/- 0.012 to 0.032 +/- 0.014. Across generations, the heritability and common environmental effect estimates were low (0.056 +/- 0.014 and 0.039 +/- 0.005, respectively) and significantly different from zero (P<0.05). Heritability of harvest body weight in females was significantly higher than that in males across populations. However, the genetic correlation of harvest body weight between sexes across population was close to unity (0.942 +/- 0.070), indicating that body weight in male and female shrimp is most likely controlled by the same genes. The response to selection in harvest body weight was estimated by two methods (the realised and predicted responses). The realised response was estimated from the difference in the least squares means of body weight for the selection and control populations, while the predicted response was obtained from the difference in the mean breeding values between generations. The back-transformed realised response was 26.22%, while the predicted responses estimated using two set of genetic parameters obtained from within- and across-generations datasets were 18.06% and 12.38% in actual units, respectively, after performing four selections. The results are discussed in relation to selection work with other farmed shrimps, and solutions for increasing and disseminating genetic gain are outlined. (c) 2012 Elsevier B.V. All rights reserved.