Effects analysis of morphometric attributes on body weight for Egyptian strain of Oreochromis niloticus in different growth phases

To study the effect of morphometric attributes on body weight of Egyptian strain of Oreochromis niloticus in different phases,119 fries were injected with RFID electronic tags to track and measure growth characteristics for comparative analysis. The attributes used in this study included total length,standard length,body depth,head length,caudal peduncle length,caudal peduncle depth,body width and body weight. Correlation coefficients matrices were constructed,in which the body weights were used as the dependent variable and other morphometric attributes as independent variables for correlation analysis and path analysis. The correlation coefficients,path coefficients and determination coefficients were calculated,and major morphometric attributes were determined. The results showed that all the correlation coefficients between each independent variable and dependent variable(body weight) were significantly different(P 0. 01) in the total two different phases. In the first phase(2- 13 months),the trait with the path coefficients of significant difference(P 0. 01) were total length(0. 417),body depth(0. 339) and body width(0. 212). The multiple regression equation rela-ting the body weight was established as y =- 307. 492 + 13. 667 X1+ 29. 638 X4+ 3. 545 X7,where y was body weight, X1,X4and X7were total length,body depth and body width respectively,and correlation index of equation was 0. 862. In the second phase(14- 25 months),the trait with the path coefficients of significant difference(P 0. 01) were body depth(0. 550) and total length(0. 387). The multiple regression equation relating the body weight was established as y =- 68. 559 + 82. 443 X4+ 22. 717 X1,where y was body weight,X1and X4were total length and body depth respectively, and correlation index of equation was 0. 784. The results above indicated that morphological traits impacted body weight differently in Egyptian strain of Nile tilapia of different culture phases. We should pay more attention in selecting key morphological traits in complex traits selection to improve the accuracy of breeding projects.