Estimation of Live Weight of Calves from Body Measurements within Different Genetic Groups

Body weight, chest girth, body length and wither height were monitored on 731 animals comprising 228 Bunaji or White Fulani (WF), 70 Sokoto Gudali (SG), 380 Friesian x White Fulani (Fr x WF) and 53 Charlolais x Sokoto Gudali (Ch x SG) calves over a 24-month period at the National Animal Production Research Institute (NAPRI), Shika, Nigeria. The effects of breed, sex, season and body conditions on these measurements were also investigated. All the variables examined, except sex, had significant (P<0.001) effects on all body measurements. Sex differences were significant (P<0.05) only for wither height. Linear body measurements were significantly (P<0.05) greater for the SG than for WF breed at the same age, while differences between the Zebu and the crossbred cattle were not significant. Values obtained for measurements taken during the rainy season were significantly (P<0.05) higher than for the dry period. Similarly, fat animals had higher measurements than lean animals, and so were the measurements for male as compared to female animals. All phenotypic correlations between body measurements were positive and significant (P<0.001). The highest correlation coefficient was found between chest girth and body weight. The polynomial equation using chest girth as an independent variable predicted body weight more accurately within breed as compared to the linear equation