Liveweight gain, herbage intake, and ingestive behaviour in Compudose®-treated and untreated steers at pasture

Twenty 14-month-old Friesian steers and sixteen 14-month-old Angus cross steers were randomly assigned within 'breed' to Compudose® treatment (24 mg of oestradiol-17β impregnated in a silicone rubber implant with an active life of 200 days) or left untreated. Fasted liveweight gain (LWG) of the steers was recorded as were calculated herbage intakes and grazing behaviour, measured on two occasions (days 34-50 and days 168-184 of treatment). Compound-treated steers gained a mean of 856 g/day compared with 710 g/day by the control steers over the treatment period (20.6% increase, P < 0.001). The final fasted liveweight of treated steers was improved by 29.5 kg (7.1%) over that of the untreated steers (P < 0.001). There were no significant differences in the amount of herbage eaten or in components of grazing behaviour between the treated and untreated groups. Under pastoral conditions, as in feedlots, Compudose treatment appears to increase both LWG and the efficiency of that gain.