title: Implant sequence effects in intact male Holstein veal calves: live and slaughter traits.
abstract: Seven sequences of growth promotant implants were used in special-fed intact male Holstein veal calves (n = 443). Calves received implants 4 d after arrival at the veal barn, 42, and 84. The following implants were used: placebo (0), Z (36 mg zeranol), ET (20 mg estradiol, 200 mg testosterone), EP/2 (10 mg estradiol, 100 mg progesterone), EP (20 mg estradiol, 200 mg progesterone), and EBA (24 mg estradiol, 120 mg trenbolone acetate). The following sequences were compared: 0-0-0 (negative control), 0-ET-ET, Z-ET-ET, 0-EP-EP, Z-EP-EP, 0-EP/2-EBA, and Z-0-EBA. From 0 to 42 d, Z implants increased (P<.05) ADG by 3.4% compared to placebo. However, implant schemes without an initial Z implant (0-ET-ET and 0-EP-EP) had higher (P<.05) mean ADG for the period from d 42 to 84. From 84 d to the end of the experiment, only the 0-EP/2-EBA treatment increased (P<.05) ADG compared to 0-0-0. Over the entire trial 0-ET-ET, 0-EP-EP, Z-EP-EP, and 0-EP/2-EBA implant sequences increased (P<.05) ADG by 3.2, 3.2, 2.4, and 4.7%, respectively, compared to the 0-0-0 sequence. Blood traits measured within 2 wk before slaughter were not affected by implant sequence, except that sequences with EP had higher (P<.05) leukocyte counts than were observed for the other sequences. Testicular weight was less (P<.01) for all of the implant sequences than for the negative control and less (P<.05) for Z-ET-ET than for 0-ET-ET, 0-EP-EP, 0-EP/2-EBA, and Z-0-EBA. The type and frequency of medical treatments did not differ among implant sequences for any of the 42-d phases, or over the entire trial. Generally, the growth promotant implants currently approved for beef cattle resulted in approximately 50% of the increase in growth rate in Holstein intact bull calves, as has been observed in beef-type steers or heifers.
authors.affiliation: Department of Dairy and Animal Science, The Pennsylvania State University, University Park 16802, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Smith
authors.forename: L L
authors.initials: LL
authors.lastname: Wilson
authors.forename: D L
authors.initials: DL
authors.lastname: Swanson
mesh_terms: D000818:Animals; D002417:Cattle / Q000254:growth & development*; D003692:Delayed-Action Preparations; D004338:Drug Combinations; D004435:Eating; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology; D004968:Estrogens, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology; D012739:Gonadal Steroid Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008460:Meat; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology; D013739:Testosterone / Q000008:administration & dosage / Q000494:pharmacology; D014204:Trenbolone Acetate / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D015029:Zeranol / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D003692:Delayed-Action Preparations; D004338:Drug Combinations; D004968:Estrogens, Non-Steroidal; D012739:Gonadal Steroid Hormones; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D015029:Zeranol; D014204:Trenbolone Acetate