Species dependent correlation analysis and regression models of body weight on linear body measures in indigenous sheep and goats of Zimbabwe

Abstract

Measurements of live weight in goats and sheep are an important source of information for a range of scientific fields and applications in animal husbandry activities. The study was conducted to investigate the relationship between body weight and body measurements and to predict live body weight from body measurements in indigenous Matabele goats and indigenous Sabi sheep at Matopos Research Station in Zimbabwe. For this purpose, data on body weight (BWT) and linear body measurements (LBM) such as heart girth (HG), body length (BL), wither height (WTH) and rump height (RH) were collected from randomly selected females of each species of the age of 4 years. The corresponding means, standard deviations (SD), and coefficients of variation (CV) were determined for body weight and linear body measurements. Bivariate correlations between bodyweight and linear body measures characteristics were also determined. Simple and multiple regression were used to develop a model to predict BWT using linear body measures. Indigenous Matabele goat females’ CV ranged from 15.77% to 22.68%, while indigenous Sabi sheep females’ CV ranged from 19.16% to 19.37%. The CV was calculated by dividing the mean by the standard deviation. At 4 years of age, the mean BWT of the indigenous Sabi sheep and female Matabele goat were 35.96 ± 0.83 kg and 27.90 ± 0.66 kg, respectively. In indigenous Matabele goat females, the average linear body measures were HW (74.20 ± 0.53 cm), WTH (48.55 ± 0.53 cm), BL (47.53 ± 0.61 cm), and RH (57.50 ± 0.88 cm). The mean values for native Sabi sheep were 63.33 ± 0.70 cm, WTH (52.00 ± 0.80 cm), BL (51.26 ± 0.78 cm), and HW (85.56 ± 1.04 cm). The results showed a strong and positive correlation between BWT and linear body measures in female indigenous Matabele goats. The phenotypic correlation values were HG (r = 0.79), BL (r = 0.70), WTH (r = 0.68), and RH (r = 0.56), in decreasing order. In indigenous Sabi sheep the phenotypic correlation for BWT and linear body measurement was high and positive for HG (r = 0.73) with positive and moderate to low with WTH (r = 0.41), BL (r = 0.32) and RH (r = 0.36). Again, the results also indicated that HG had a high and positive phenotypic correlation with BL (r = 0.53) while modest correlation was observed with HG and WTH (r = 0.41) and HG and RH (0.32). The optimal regression models for easily measuring body weight using HHG are BWT = −46.711 + 1.006HG (R² = 60%) and BWT = −15.209 + 0.586HG (R² = 53%) for indigenous Matabele goats and indigenous Sabi sheep, respectively. It is recommended that smallholder farmers use HG measurements to estimate body weight in both indigenous Sabi sheep and indigenous Matabele goat females at the age of 4 years.