Growth promotant implants in suckling calves and stocker cattle

Mode of action, performance response, and practical recommendations

Abstract

Growth promotant steroid implants increase average daily gain (ADG) by approximately 5% when used in suckling calves, and approximately 14% when used in stocker cattle. Implants used during the suckling or stocker phase do not affect subsequent growing or finishing performance, nor diminish the performance response to implants used during subsequent production phases. Weight added due to the use of implants is, generally speaking, cumulative over the productive life of the animal. In carcasses with a similar degree of marbling, implants do not affect tenderness or eating satisfaction of beef. Dosage of implant should be matched to the weight and age of the animal and to the level of nutrients available; that is, suckling calves should be given a mild implant approved for use in suckling calves, whereas weaned stocker calves grazing a moderate-quality and abundant-quantity forage base should be given a moderate dose implant approved for use in grazing cattle. There is a risk that implants given to replacement heifers at birth may reduce subsequent pregnancy rate; if a single estrogenic implant is provided after 1 to 3 months of age the risk is minimal. A 5% increase in ADG for calves gaining 1.88 lb (0.85 kg)/day for 100 days after implant administration through weaning equates to 9.4 additional pounds (4.26 kg) per calf for sale at weaning, which, based on a $1.82/lb market value for 500 lb (226.80 kg) calves with a 14 cent/lb slide from 500 to 600 pounds (226.80 kg to 272.16 kg), results in an additional $10.40 per calf sold at weaning.