This study aimed to investigate sources of variation of average daily gain in beef cattle, with an on farm approach, in the Veneto region. Data of 38707 animals fattened in 29 farms and belonging to 5 genotypes (Charolais, Charolais Female, French Crossbred, Limousin and Polish Friesian) were analysed considering type of farm, farm nested within type, genotype, housing system, arrival live weight, percentage of dead and injured animals, season of sale and diet. Genotype, farm, percentage of unhealthy animals and season of sale significantly affected average daily gain. Charolais and French Crossbred showed the highest values of average daily gain, Charolais Female the lowest. The effect of farm suggests that management is very important for growth performance in beef cattle. Moreover, batches of animals with high percentage of dead and injured presented lower values of average daily gain. In spring-summer 2003 an extremely hot climate was unfavourable for growth performance.