Genetic parameter estimation for growth traits of Pacific white shrimp(Litopenaeus vannamei)

Abstract

Eighteen half-sib families and fifty-four full-sib families were constructed using methods of nest design and artificial insemination,in which each male mated three females.Sixty 5-month-old shrimp were measured for nine growth traits including the body weight(BW),the total length(TL),the body length(BL),the carapace length(CL),the carapace width(CW),the carapace depth(CD),the first abdominal segment depth(FASD),the third abdominal segment depth(TASD),and first abdominal segment width(FASW).According to quantitative genetics theory,the heritability of each growth trait,and the genetic and phenotypic correlation among the traits were statistically studied utilizing the method of variance and covariance analysis.The results showed that the heritability estimates in the narrow sense from intra-group correlation of paternal half-sib were precise and unbiased,and the heritability values for the above nine traits were 0.460,0.392,0.303,0.234,0.251,0.330,0.282,0.321 and 0.356,respectively.All of them belonged to moderate and high heritability,thus showed a high potential for selective breeding.The estimates of genetic correlation coefficients were 0.750-0.976,where the highest(0.976)was that between the BW and the TL,while the lowest(0.750)was seen between the TL and the TASD.The estimates of phenotypic correlation coefficients were 0.507-0.947,where the highest(0.947)was seen between the BW and the TL,while the lowest(0.507)was that between the FASD and the CD.Very significant difference was detected by t-test(P0.01)among the nine growth traits for both genetic and phenotypic correlation coefficients,which indicate all the nine traits may respond favorably to direct and indirect selection for growth.