Predicting Body Weight of Three Ethiopian Thin-Tailed Sheep Breeds from Linear Body Measurements

Abstract

Growth and conformation are the most important characteristics in small ruminant production for live animal sale and meat production. Linear body measurements are also important parameters to measured growth and as a selection criterion for breeders and prediction of body weight in sheep. Weight is determined by estimating some linear parameters under field condition where weighing scale is inaccessible. The study was conducted to examine the relationship between the body weight and morphological traits of three Ethiopian thin-tailed sheep breeds, Begait, Gumz and Rutana. A total of 327 ewes, the average age of 2-4 years, were used for body weight and body linear measurements. Morphological data on body length, heart girth, height at withers, tail length, pelvic width, ear length, rump height, and rump length and body weight were measured using standard descriptor adopted from Food and Agriculture Organization. Mean, standard error and coefficient of variance of weight and linear measurements of each breed were analyzed and tested for significance using the GLM procedure of SAS. Least square means and standard error of body weight of Begait, Gumz and Rutana sheep were found to be 39.79 ± 0.65, 36.27±0.62 and 43.10±0.69, respectively. Most variables were significantly p<0.05 and positively correlated with body weight. All sheep populations showed the highest correlation between body weight and heart girth with a correlation value of 0.72, 0.85 and 0.77 for Begait, Gumz and Rutana, respectively. Two of the body measurements heart girth and pelvic width were fitted for the model with a coefficient of determination R2 value in the range of 52-77% of the live weight in Begait sheep. Four body measurements heart girth, body length, and chest depth and ear length were fitted for the model with a coefficient of determination R2 in range of 72 to 81% for Gumz sheep. Four body measurements heart girth, body length, pelvic width, and chest depth were best fit for the model with coefficient of determination R2 value in the range of 55 to 87% for Rutana sheep. Rutana sheep population has higher p<0.001 body weight followed by Begait. Except for body weight and tail length, Rutana and Begait sheep populations have statistically similar body measurements. Gumz Sheep have P<0.05 lower body weight and body linear measurement than the others. In this study, the body measurements had a positive and high correlation with body weight implicating that linear body measurements can be used for estimation of body weight. In all studied sheep populations and age groups, heart girth is the first predictor that best fit for the model. The mean actual body weight and predicted body weight have shown almost similar value for all sheep populations and age groups. Therefore, prediction of body weight using only heart girth is preferred due to its reasonable precision and reasonably easy as a single measurement.

Keywords: Body weight, linear body measurement, regression equation, thin-tailed sheep