Abstract:The objective of this study on Pacific white shrimp (Litopenaeus vannamei) was to evaluate the fillet yield performance of different families in the conservation population. A multivariate linear regression equation of fillet yield was established to find alternative indirect traits of fillet yield. A total of 2094 shrimps from 42 full-sib families were randomly sampled for measuring phenotypic traits and fillet yield in the conservation population after rearing 350 days. These traits were measured for each shrimp: fillet weight(FW), body weight(BW), carapace length(CL), segment length(SL), the length from the base of eye stalk to the 6th segment(ESL), body length(BL), total length(TL) and condition factor(CF). Fillet yield was obtained after anatomizing the shrimp and taking the meat. Differences of fillet yield between different families were analyzed using the ANOVA method. The component of variance and heritability of fillet yield trait were estimated using REML method and an individual animal model. Correlation coefficients between the phenotypic traits and fillet yield were calculated, and the prediction equations for fillet yield were established using step-wise regression analysis method. The results showed that the average fillet yield was 53.59% in L. vannamei. The mean of fillet yield between families ranged from 50.25% to 59.51%. The variation coefficient of fillet yield was 6.08% and there were significant differences between families (P<0.01). Three traits having strong correlation with fillet yield were FW (r=0.478), ESL (r=0.376) and SL(r=0.370). The multivariate linear regression equation for fillet yield was composed of ESL, BW and ESL/TL, and the coefficient of determination of the equation was 0.172. This study first implied that difference between families for fillet yield was significant. Although genetic variation for fillet yield was poor at the family level in the conservation population of L. vannamei, improved strains or populations will be introduced to increase genetic gain of fillet yield, and desirable genetic gain will be obtained using inter-family and within-family selections. Indirect selection traits with moderate correlation with fillet yield were found because correlation coefficient between phenotypic traits and fillet yield varied from low to moderate. In this study, the prediction accuracy of the constructed multiple linear regression equation for predicting fillet yield was low. Therefore, new technologies including ultrasound, magnetic resonance imaging should be developed, and new traits including cross-sectional area of muscle, circumference of segment should be measured in the future study.
