Assessment of the relationship between body weight and body measurement in indigenous goats using path analysis

Abstract

Body measurements have been used in animals to estimate body weight especially in rural areas where scales are not readily available. The study was conducted in Sekhukhune District of the Limpopo province, South Africa where the goats between the ages of 20 and 30 months were used. Body weight and four morphological traits were taken on each goat in the morning before they were released for grazing in a total of 613 indigenous goats of both sexes (62 male and 551 female). Body weight was measured in kilogram (kg) using a balance scale, hip height and shoulder height measurement (cm) were done using a graduated measuring stick and the body length and heart girth were measured in centimetre (cm) using a tape rule. Means, standard deviations (SD) and coefficients of variation (CV) of body weight and morphological traits were calculated. Pair wise correlations among body weight and morphological traits were also determined and range from 0.81-0.91 for male and 0.72-0.89 for female goats, respectively and were significant (P<0.01). The direct effect of heart girth on body weight was the strongest in both sexes (path coefficient of 0.58 and 0.62 in males and females, respectively). Body length (males) and body length and hip height (females) also positively (P<0.05) influenced body weight. The direct effects of other linear type traits on body weight in both sexes were non-significant as revealed by t-test. These traits were indirectly realized mostly via heart girth. Thus, they were removed from the final regression equations to obtain much more simplified prediction models. The optimum multiple regression equation for male goats included heart girth and body length, In female goats, however, the v variables included in the final prediction model were heart girth, body length and shoulder height. The forecast indices obtained in this study could aid in weight estimation, selection and breeding programmes