|
Litopenaeus shrimp (Litopenaeus vannamei) has a good adaptability to the excellent characteristics of the fast growth rate, strong disease resistance and resilience, and thus the shrimp species is introduced into our country and get a wide range of promotional results Litopenaeus vannamei coastal and inland areas has now become the main varieties of shrimp farming, aquaculture accounted for shrimp farming 70%. As Litopenaeus vannamei China Sea natural distribution, so China's only multi-generation breeding years ago broodstock from abroad to keep seed offspring. Litopenaeus vannamei introduction groups do not have to take rigorous and systematic breeding and the original species preservation, the result of the Litopenaeus vannamei growth traits showed significant changes, including reduced incidence of favorable performance, but poor performance including slow down the growth rate, extend the breeding cycle and a serious differentiation of individual size. In recent years, in order to alleviate the Litopenaeus vannamei growth traits degradation, some of our departments again introduced from abroad a large number of broodstock, take these can really make broodstock Fl on behalf of good growth traits, but the resilience or lower . Although F2 has a high ability to withstand adversity, but growth traits significant degradation, in addition to the introduction of a large number of broodstock lead to substantial loss of foreign exchange. Because of the above reasons, so as soon as possible Litopenaeus vannamei original species conservation and breeding system. This study established in Litopenaeus vannamei cultivation of new varieties on the basis of, regression analysis and discriminant analysis between the growth traits associated with the target traits, with an estimated Litopenaeus vannamei May the Growth Character genetic parameters for Savannah The vannamei selective breeding to provide basic parameters of the scientific and rational way to guide the practice of shrimp production. The main contents are as follows: a of L. vannamei morphological traits on weight stepwise regression analysis to select the 5-month-old Savannah shrimp 900, measured total length, body length, the first abdominal segment back third abdominal segment back the first abdominal segment back width, carapace length, carapace width, carapace height and weight of 9 traits, correlation analysis and path analysis to calculate various morphological traits and body weight between any two path coefficient and the coefficient of determination coefficient, morphological traits weight as the dependent variable as the independent variables, quantitative analysis of the effects of morphological traits on body weight. The results show that: the L. vannamei 8 morphological shape and weight of the correlation coefficient between any two have reached a significant level (P lt; 0.01); Path Analysis reveals the true relationship of the more independent variables in the multivariate analysis with the dependent variable, an important indicator of full-length, body length, the first abdominal segment back, back width of the first abdominal segment, carapace width and carapace high weight path coefficient reached a very significant or significant level, so they are a direct impact on weight , in which the total length of the direct impact on body weight (0.32838 **), are the most important factors that influence body weight, followed by carapace width (** 0.24249) (0.15095 **), body length, carapace (0.12038 **) and the first abdominal segment back width (0.10981 **), the first abdominal segment back directly affect the high weight (0.04922 *) minimum; third abdominal segment back high correlation with weight coefficient (0.73571 ** ), but with the direct impact of carapace length on body weight are very small, they mainly through other traits related to indirect effects of body weight, secondary factors influence body weight, were excluded; coefficient of determination and path analysis The results have a consistent trend, selected morphological traits and body weight of the multiple correlation coefficient R2 = 0.9449, the main independent variables that influence body weight has been found; stepwise regression analysis to establish a full-length (X1), body length (X2), the first an abdominal segment back (X3), the first abdominal segment back width (X5), carapace width (X7) and carapace height (x8) of body weight (Y) multiple regression equation, the regression intercept and the corresponding regression the coefficients were -22.599,1.043,0.547,0.969,2.279,6.118 and 2.797, this study provides a theoretical basis for the shrimp breeding. 2 of L. vannamei months of age traits. Principal component and discriminant analysis in order to study the growth law of L. vannamei traits and determine miss the best growing season L. vannamei in line with its size months of age, the study, from January to June age of L. vannamei 1000 each measured length, body length, the first abdominal segment back, the third abdominal segment back, back width of the first abdominal segment, carapace length and weight of 7 traits, the use of the main composition and discriminant analysis method. The results showed that: L. vannamei traits of the old and showed a significant positive correlation (P lt; 0.01), the most obvious of which the total length and body length, 1-month-old Savannah shrimp weight and morphological traits related coefficient is small. The main component of the old and Litopenaeus vannamei, Litopenaeus vannamei vary ,1-2-month-old first main component length factor, and the second main component width factor, the third main component of the height factor; Where a 3-month-old vannamei the first principal component with 1-2 month-old Savannah shrimp, but the second principal component height factor, the third main component of the weight factor; L. vannamei first 4-6 months of age - the main component of weight factor, a second main ingredient for a height factor, the third main component is a width factor. These results can be analyzed :1-3-month-old Savannah shrimp morphological traits developmental priority in weight, but the development of the 4-6 month-old Savannah shrimp morphological traits weight catch up. Miss the best growing season of L. vannamei its size matches the month-old discriminant described in this article to determine the discriminant results: total discriminant accuracy rate of 98.98%, of which 2-4 month-old Savannah shrimp The discriminant accuracy rate of 100%. 3 L. vannamei May age growth traits genetic parameters of the estimated system design (nested design), the end of each male shrimp mating three female shrimp, completed a total of 21 paternal half-sib family system, and 47 full-sib family system, respectively. measured total length (TL), body length (BL), carapace length (CL), carapace width (CW), the carapace (CD), the first abdominal segment back (FASD), third abdominal segment back (TASD), back width of the first abdominal segment (FASW) and body weight (BW) and other 9 traits, the total number of shrimp measurement 1387. Use of the MANOVA analysis methods, the use of multivariate mixed animal models the MtdfremL software analysis to estimate the heritability and genetic correlation coefficient. The results show that the total length (TL), body length (BL), the first abdominal segment back (FASD), the back of the third abdominal segment (TASD) first abdominal segment back width (FASW), carapace length (CL ), carapace width (CW), carapace (CD) and body weight (BW) heritability was 0.39 ± 0.08,0.30 ± 0.07,0.23 ± 0.09,0.25 ± 0.05,0.33 ± 0.12,0.28 ± 0.06 , 0.32 ± 0.07,0.35 ± 0.14,0.46 ± 0.11, are moderate heritability Range, one of the first abdominal segment back (FASD), the lowest heritability, the highest heritability of body weight (BW). The various traits showed high positive correlation length (TL) and body weight (BW) of the genetic correlation maximum length (TL) and third abdominal segment back TASD genetic minimum.
|