Using factor analysis to characterise the body structure of male and female indigenous Tswana goat at kid and grower ages

Abstract

The objectives of this study were to estimate the relationships among body measurements and determine underlying factors that define the body structure in male and female Tswana goats at kid and grower ages. Body weight (BW), body length (BL), heart girth (HG), height at withers (WH), shoulder width (SW), neck length (NL), tail length (TL) and ear length (EL) were recorded from 273 female and 278 male kids and, 699 female and 281 male growers. Fifteen farmers keeping goats were randomly selected from each district excluding Tsabong and Ghanzi districts and records taken on a random sample of 4-12 animals per farm in 2004. Data were analysed using Procedures PRINCOMP and FACTOR ROTATE in Statistical Analysis System. Strong (r >0.70) and significant (P<0.05) correlations were found between BL, WH and HG for female and male kids. In female kids, moderate and significant correlations (r=0.50 to 0.70) were found between BW, TL, NL and TL for male kids. In growers, BW correlated strongly to HG in females and moderately to BL. For males, BW correlated strongly to WH and HG and moderately to BL. For female kids, one factor, general body size explained 54% of the total variability while two factors, general body size and shoulder width explained 72.3%. Important variables in characterising kids were WH, HG and BL with SW also important for male kids. For female growers, three factors, NL, BL and SW explained 58.4% while for male growers, two factors, general body size and shoulder width explained 61.3% of the total variability. Generally in characterising growers, SW and HG were important variables while BL and WH were also important for female and male growers respectively. Factor analysis can be used to characterise the body structure of female and male Tswana kids and growers using fewer variables.