Non genetic factors affecting calf growth traits in mashona cattle

The objective of this study was to evaluate the effects of sex of calf, year of birth, age of calf and age of dam on growth traits of indigenous Mashona calves. The growth traits under study were weaning weight (W2), yearling weight (W4) and 600day weight (W6). Data from 1834 purebred Mashona calves were employed, which included calf identity, year, sex, age, sire and dam, as well as age of dam. The data was analysed using the General Linear Models (GLM) procedure of the Statistical Analysis System. Tukey’s multiple range tests were performed for testing differences between least square means. Weaning weight increased as dam age increased up to 10 years after which growth tended to decline. Post-weaning compensatory growth was apparent in calves of young dams. Male calves grew faster and were heavier at all stages than female calves. Sex of calf and age of dam significantly affected calf weaning, yearling and 600day weights. A number of years showed a significant difference from each other for all the traits measured. Records of these traits should always be adjusted for sex of calf, year effects and age of dam so as to increase the accuracy of estimation of breeding values as well as rate of genetic gain per generation of selection.