Modeling the relationships of growth and morphometrics to dress-out traits in the oriental river prawn, Macrobrachium nipponense

Abstract

Macrobrachium nipponense is a crustacean species of economic importance. The dress-out traits in this species cannot be directly selected for improvement due to their failure to be reliably measured. In this study, the path analysis approach was used to make clear how much dress-out traits were determined by growth (body weight at harvest) and morphometrics (body length, chela length, abdominal length, cephalothorax width, second abdominal segment width, second abdominal segment height). Then efforts were made to establish reliable prediction models of dress-out traits in both sexes. Results showed that abdominal meat weight was 0.69 (± 0.17) g for females, and 0.75 (± 0.25) g for males; abdominal meat percentage was 34.67 (± 4.21) %, and 33.94 (± 4.85) %. Body weight was the only determinant of abdominal meat weight in both sexes (P < 0.01), whereas the coefficients of determination of growth and morphometrics on abdominal meat percentage were all nonsignificant in both sexes (P > 0.05). According to the results of path analysis, models of abdominal meat weight on body weight were established, with R2 value reaching 0.952 for females, and 0.949 for males. Residuals analysis showed the adequacy of the abdominal meat weight models. The shrinkage on cross-validation of the abdominal meat weight was 0.004 for females, and 0.006 for males, showing the applicability of the models. Growth and morphometrics were not able to be used for predicting abdominal meat percentage. In practical breeding program of this species, direct selection of abdominal meat weight can be pursued through predictions using the reliable models established in our study, alternatively indirect improvement of abdominal meat weight through direct selection for growth. Abdominal meat percentage is not suggested for the target of improvement in M. nipponense.