Vet Life - Controlled release implant provides an effective daily dose of estradiol for suckling steers, pastured growing steers, and finishing steers and heifers for 400 days. No additional effectiveness may be expected from re-implanting. In less than 400 days. Implant time: suckling steers: at castration or later; pasture steers: at weaning; finishing steers and heifers: at arrival at feedlot. No withdrawal.