The effects of 5 different implant programs on the health outcomes, growth performance, and carcass characteristics of lightweight beef steers

Abstract

Objective

Our objective was to evaluate 5 different implant programs on the health outcomes, growth performance, and carcass characteristics of lightweight beef steers.

Materials and Methods

Crossbred steers (n = 3,817; initial BW 195 ± 1.1 kg) were used in a randomized complete block design and fed to a common number of days on feed (280 d). Steers were blocked by time of arrival (n = 10 blocks) and assigned randomly to 1 of 5 treatments: (1) 200 mg of trenbolone acetate (TBA) and 40 mg of estradiol 17β administered on d 0 (XS0); (2) 200 mg of TBA and 40 mg of estradiol 17β administered on d 60 (XS60); (3) 200 mg of TBA and 40 mg of estradiol 17β administered on d 80 (XS80); (4) 200 mg of TBA and 40 mg of estradiol 17β administered on d 100 (XS100); and (5) 80 mg of TBA and 16 mg of estradiol 17β administered on d 0 followed by 200 mg of TBA and 40 mg of estradiol 17β administered on d 80 (IS-XS).

Results and Discussion

The proportion of steers treated once for bovine respiratory disease was less in XS60 and XS100 than XS0, XS80, and IS-XS. No difference was noted in mortality among treatments. Steers in XS0 and IS-XS had greater DMI than XS60, XS80, and XS100. Gain:feed differed among treatment, in which XS60, XS80, and XS100 had greater G:F than XS0 and IS-XS, both with dead and removed steers included and excluded. No differences were observed in carcass traits, except in fat thickness, marbling, and estimated empty body fat, indicating that implant timing influences carcass characteristics.

Implications and Applications

In steers fed more than 220 d, delaying Revalor-XS for 60 or 80 d after arrival does not differ from using a reimplant strategy in which Revalor-IS was followed by Revalor-XS or administering Revalor-XS on d 0. Delayed implantation with an extended-release implant can meet new US Food and Drug Administration guidelines without negatively affecting growth performance or carcass quality.