Abstract
In this study, genetic parameters were obtained for growth and cold tolerance of 99 Fenneropenaeus chinensis juvenile families by means of indoor artificial cooling (starting from 14°C, 2°C/d). A linear mixed model was fitted to estimate variance components using the ASReml software package. Heritabilities estimated for body weight (BW) and body length (BL) of F. chinensis juveniles were 0.078 ± 0.124 and 0.131 ± 0.133, respectively. The estimates of heritability were low in magnitude for both traits. The differences between the heritabilities estimated for the two growth traits were not significant with each other, and the heritabilities were not significantly different from zero (P > 0.05). The phenotypic and genetic correlation coefficients between BW and BL were as high as 0.9408 ± 0.0040 and 0.9562 ± 0.0551, respectively, and both were significantly different from zero (P < 0.01). The heritabilities of temperature at death (TAD) and cooling degree hours (CDH) were 0.265 ± 0.091 and 0.077 ± 0.058, respectively. The heritability estimates for TAD was moderate and significantly different from zero (P < 0.01). The correlation analysis indicated that the phenotypic correlation coefficient between TAD and CDH was -0.5470 ± 0.0174, and the genetic correlation coefficient was -0.6707 ± 0.3635. In the analysis of growth traits and cold tolerance traits, the values of phenotypic correlation coefficient were floating between -0.1055 and 0.1098, both were significantly different from zero (P < 0.05), while the genetic correlation had a larger range (0.0526 ~ 0.9914), and all were not significantly different from zero (P > 0.05). In this study, there was a low correlation between growth and cold tolerance traits, indicating that growth traits and cold tolerance traits should be considered collectively in the breeding program of shrimp.
Highlights
The mean of body weight (BW), body length (BL), temperature at death (TAD), cooling degree hours (CDH) and survival rate for each family at half lethal time (SR50) were 0.073g, 19.790mm, 6.506 ̊C, 333.937 ̊Ch, 48.950%, respectively, with coefficient variation ranging from 18.226% to 59.919%
The phenotypic and genetic correlation between BW and BL were as high as 0.9408 ± 0.0040 and 0.9562 ± 0.0551, respectively, which were significantly different from zero (P < 0.01). These results indicated that growth traits (BW and BL) were highly correlated
The research results showed that the heritabilities for body weight and body length of F. chinensis juveniles were low (0.078 ± 0.124 and 0.131 ± 0.133, respectively)
Summary
Facing the difficulty in the farming of shrimp, breeding staff, after a long struggle, developed 3 new varieties of Chinese shrimp namely “Huanghai No 1” (2003), “Huanghai No 2” (2008) and “Huanghai No 3” (2013) [3,4,5], which enabled gradual recovery of China’s farming of F. chinensis. The intensified abnormal climate especially repeated cold disaster nationwide has resulted in mortality of a large number of shrimps and serious economic losses to shrimp farmers; on the other hand, the optimum temperature of F. chinensis restrains breeding season and region, and further restrains pond stocking time and harvest specifications of shrimp, and indirectly affects yield and benefit of breeding, and the breeding of cold tolerance varieties is expected to solve all the above problems
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