In order to increase milk production per cow, Friesian cows are being bred to Holstein bulls. As yet, there are few pure-bred Holsteins in commercial production in Ireland but there are increasing numbers of Holstein x Friesian and Holstein x (Holstein x Friesian) calves available for beef production. The main difference between Holstein and Friesian steers is that the former have poorer carcass conformation. The use of anabolic agents and an increase in slaughter weight might improve carcass conformation. The objectives of the present experiment were (1) to compare the growth and carcass composition of 3/4 Holstein and Friesian steers, (2) to measure the effects of implantation with anabolic agents in both these breed types, (3) to determine the effects of a higher feeding level and delayed slaughter on carcass traits.