Path analysis of the relationship between body weight and some linear characters in West African Dwarf sheep

Abstract

The usefulness of correlation analysis in life sciences is enhanced when the coefficient is partitioned into direct effects of one trait on the other and indirect effects caused by other characters which may be of importance in selection. A total of 417 mature (>22 months) West African Dwarf (WAD) sheep comprising of 201 rams and 216 ewes intensively reared were used for this study. Data were taken on body weight (BW) and 19 linear conformation traits. Linear body measurements considered were rump width (RW), rump length (RL), tail length (TL), wither height (WH),thorax depth (TD), shin circumference (SC), heart girth (HG), paunch girth (PG), rump height (RH), ear length (EL), fore-leg length (FLL), rear-leg length (RLL), body length (BL), shoulder width (SW), neck circumference (NC), head length (HL), head width (HW), horn length (HoL) and hock length (Hock). Descriptive statistics and path coefficients were computed. Correlation analysis was also explored to determine the degree of association among variables. Sexual dimorphism was observed in all traits considered (p< 0.05), except RL. Large coefficients of variation were obtained for BW, PG and NC relative to other traits considered. All linear traits had significantly positive (p< 0.05) correlations with BW in both sexes. The ranges of correlation between BW and all linear body parameters were, 0.227–0.726 and 0.183–0.878 in rams and ewes, respectively. The highest correlations with BW in rams and ewes were obtained for HG and NC, respectively. Significant path coefficients were obtained for HG and TD in rams while HG, FLL, PG, NC and RL had significant (p< 0.05) path coefficients in ewes. Though many predictor variables were considered in this study, it was concluded that HG contributed most to the coefficient of determination in both sexes. Moreover, all other predictor variables with similar (p> 0.05) path coefficients had high correlations with BW, their indirect effects were obtained mostly through HG.