Measures of relationships and association among body weight and biometric traits of donkeys in Northwest Nigeria

Body linear measurements of different age categories of donkeys were used to predict the body weight of donkeys using stepwise regression procedure. This work was conducted to estimates the live body weight of donkeys from biometric traits. A total of 700 donkeys were measured into three age groups (weaners 6 months- 1 year, young above 1- 3 years and adults 3 years and above). Morphometric measures taken were body weight, head length, head width, ear length, neck length, neck circumference, shoulder width, height at withers, heart girth, body length and tail length using random sampling technique. Significant variations were observed in morphometric (P<0.05, P<0.01) traits. The results of the study showed that significantly (P<0.01) predicted body weight of these donkeys with good efficiencies were neck circumference (NC), tail length (TL) and body length (BL) were the best predictors of body weight with R2= 100% in weaners, head width (HWD), neck circumference (NL), neck circumference (NC) and height at withers (HW) with R2= 100% in young and HW, HG with R2 = 100% in adult category. The traits were significantly (p<0.05, 0.01) and positively correlated amongst themselves (r=0.09-0.87).It is therefore concluded that the inclusion of two variables improved the prediction marginally, but the addition of further variables gave little further improvement. The association may be useful as selection criterion, since positive correlations of traits suggest that the traits are under the same gene action (pleiotropy/linkage). It is therefore recommended that tail length, neck circumference, body length, height at withers and heart girth should be used as the best predictors of body weight across the sex and age categories of donkeys.