Bioprediction of Body Weight from Zoometrical Traits of Nondescript Goats using Linear and Non-Linear Models in North Central Nigeria

Data on body weight and four zoometrical measurements – rump height, withers height, heart girth and body length of 135 Non-descript goats were used to develop linear, quadratic and allometric equations to predict body weight. The animals were extensively managed in north central Nigeria. They were stratified into two groups on the basis of dentition. Goats that were between 1.0–14.3 months old (milk teeth age) were classified as kids while those between 19.4–30.6 months old (animals having between 2–8 permanent incisors) were categorized as adults. Animals were also classified on the basis of incidence of wattle into wattled and non–wattled goats. Highly significant (P<0.01) coefficients of determination (R2 = 0.38–0.95) were recorded, showing the inter-relationship between body weight and the linear body measurements investigated. However, body weight was better estimated in kids (pooled data for males and females) than adult (does) goats (R2 = 0.84–0.94; MSE = 0.01–1.55 versus R2 = 0.41–0.92; MSE =0.005–16.80). Withers height appeared as the highest single prediction variable in kids (R2 = 0.91–0.94; MSE = 0.01–0.88), while in adult goats, heart girth was found to account more for variation in the body weight (R2 = 0.91–0.92; MSE = 0.005–2.54). Among the prediction equations tested, the allometric model seemed to give a better fit, closely followed by the quadratic and linear models respectively. The wattle gene impacted mostly on adult parameters where prediction accuracy appeared to be better in wattled adults compared to their non-wattled counterparts. The present findings could be exploited in designing appropriate management and selection programmes