This study was conducted to assess the impact of implanting intact beef males with protein
anabolic agents at varying intervals throughout life. Ninety-six intact males were assigned to three implant treatments: 1) not implanted, 2) implanted at 9 wk of age, weaning and at 56-d intervals thereafter with a 36-mg
zeranol implant or 3) estradiol implant at 9 wk of age and 68 d post-weaning. During the 118-d, post-weaning growing period, eight animals per treatment (one replication) were castrated. After a 114-d finishing period, cattle were slaughtered (average age of 13 to 14 mo). Feedlot performance, carcass and palatability data were obtained. Average daily gains and feed efficiency did not differ (P|.05) between
zeranol and estradiol-implanted intact males. Regardless of implant treatment, steers had lighter carcass weights (P|.05) and higher (P|.01) quality grades than intact males. Implanting either intact males or steers with
zeranol or estradiol resulted in higher (P|.05) numerical yield grades.