Estimates of strain additive and non-additive genetic effects for growth traits in a diallel cross of three strains of giant freshwater prawn (Macrobrachium rosenbergii) in Vietnam

Abstract

Additive genetic, heterotic and strain reciprocal effects were estimated using a diallel cross of two local wild strains of the giant freshwater prawn (Macrobrachium rosenbergii) in Vietnam (Dong Nai and Mekong) and a third domesticated Hawaiian strain, newly introduced to Vietnam. While some minor heterotic outcomes were detected in specific crosses, strain additive genetic and reciprocal effects were more significant sources of variation for all growth traits measured. Strain additive genetic effects were highest for the Hawaiian strain (+10.2%) and lowest for the Mekong strain (-11.6%) for harvest body weight. A similar pattern of strain additive genetic effects was observed for carapace and standard length. Average heterotic outcomes for all growth traits were small and not significantly different from zero (P>0.05), and ranged from +0.7 for carapace length to +1.5% for body weight. The reciprocal effect had a positive effect on growth rate, because crosses between the Dong Nai (D) or Mekong (M) strains as dam and the Hawaiian (H) strain as sire grew faster than did their reciprocal crosses (HD and HM). The relative high correlation between strain additive performance and total performance for all traits (r=0.71 to 0.77) suggests potential for exploiting strain additive variation to improve M. rosenbergii culture stock via direct selection among strains. A breeding strategy for genetic improvement of giant freshwater prawn in Vietnam is discussed.