The objective of this work was to study the effect of genetic and non genetic factors on weights at birth (BW), weaning (WW), yearling (YW), 18 months (EW) and 24 months (TW) of age, and weight gains from birth to weaning (GBW), weaning to yearling (GWY), yearling to 18 months (GYE), and 18 to 24 months (GET) of age, of crossbred Canchim x Nellore animals, sired by Canchim (5/8 Charolais + 3/8 Zebu) bulls. The data were studied by the least squares method with a model that included the fixed effects of year and month of birth, sex of calf, cow origin, age of cow at calving, and the random effects of sire within year. Heritabilities were obtained using the sire of calf variance component. Year and month of birth affected all studied traits, except GYE and BW, respectively. The animals were heavier and had higher weight gain when weighed during or just after the summer (from January to March). The males were heavier than the females from weaning to 24 months of age and gained more from birth to weaning, and from 18 to 24 months of age. Cow origin had an effect on WW, GWY, and GET. Age of cow had no effect on the studied traits, while sire of calf did not affect only gain from 18 to 24 months of age. The heritability estimates were 0.41 ± 0.14 (BW), 0.42 ± 0.15 (WW), 0.53 ± 0.16 (YW), 0.46 ± 0.19 (EW), 0.63 ± 0.20 (TW), 0.37 ± 0.14 (GBW), 0.33 ± 0.14 (GWY), 0.34 ± 0.17 (GYE) and 0.15 ± 0.16 (GET).
beef cattle; environmental factors; heritabilities; body weights
