TY - JOUR
T1 - Evaluation of coated steroidal combination implants on feedlot performance and carcass characteristics of beef heifers fed for constant or varying days on feed
AU - Ohnoutka, C. A.
AU - Bondurant, R. G.
AU - Boyd, B. M.
AU - Hilscher, F. H.
AU - Nuttelman, B. L.
AU - Crawford, G. I.
AU - Streeter, M. N.
AU - Luebbe, M. K.
AU - MacDonald, J. C.
AU - Smith, Z. K.
AU - Johnson, B. J.
AU - Erickson, G. E.
N1 - Funding Information:
This research is a contribution of the University of Nebraska Agricultural Research Division supported in part by funds provided by Merck Animal Health (De Soto, KS).
Publisher Copyright:
© 2021 American Registry of Professional Animal Scientists
PY - 2021/2
Y1 - 2021/2
N2 - Objective: Two experiments evaluated the effects of delayed, long-lasting implant strategies for finishing heifers fed for constant or varying days on feed. Materials and Methods: In Exp. 1, heifers (n = 500; initial BW = 280 ± 21 kg) were allotted randomly to 1 of 5 treatments, including no implant (CON), Revalor-XH on d 1 (XH), Revalor-200 on d 1 (E200), Revalor-XR on d 1 (XR), or Revalor-200 on d 70 (D200). All implants contained 200 mg of trenbolone acetate and 20 mg of estradiol. In Exp. 2, 720 heifers (initial BW = 281 ± 10 kg) were assigned randomly to treatments in a 3 × 4 factorial arrangement, with 3 implant treatments [no implant (NCON), Revalor-200 on d 1 and 100 (PCON), or Revalor-XH on d 1 (XH)] and 4 serial slaughter dates following 151, 165, 179, or 193 d on feed. Results and Discussion: In Exp. 1, implanted heifers were heavier, gained more, and were more efficient (P ≤ 0.03) compared with CON heifers, but no differences were observed among implant treatments (P ≥ 0.21) over the 198-d finishing trial. Implanted heifers had greater hot carcass weight but lower marbling scores compared with CON heifers (P ≤ 0.04). In Exp. 2, there were no serial slaughter × implant treatment interactions for growth performance (P ≥ 0.23) or carcass characteristics (P ≥ 0.31). Final BW, fat thickness, and numerical YG increased linearly (P < 0.01), whereas ADG (P = 0.01) and G:F (P = 0.02) decreased linearly, with increasing days on feed. Implications and Applications: Hot carcass weight was increased by implanting strategy and increasing days on feed, but aggressive initial implants did not improve performance.
AB - Objective: Two experiments evaluated the effects of delayed, long-lasting implant strategies for finishing heifers fed for constant or varying days on feed. Materials and Methods: In Exp. 1, heifers (n = 500; initial BW = 280 ± 21 kg) were allotted randomly to 1 of 5 treatments, including no implant (CON), Revalor-XH on d 1 (XH), Revalor-200 on d 1 (E200), Revalor-XR on d 1 (XR), or Revalor-200 on d 70 (D200). All implants contained 200 mg of trenbolone acetate and 20 mg of estradiol. In Exp. 2, 720 heifers (initial BW = 281 ± 10 kg) were assigned randomly to treatments in a 3 × 4 factorial arrangement, with 3 implant treatments [no implant (NCON), Revalor-200 on d 1 and 100 (PCON), or Revalor-XH on d 1 (XH)] and 4 serial slaughter dates following 151, 165, 179, or 193 d on feed. Results and Discussion: In Exp. 1, implanted heifers were heavier, gained more, and were more efficient (P ≤ 0.03) compared with CON heifers, but no differences were observed among implant treatments (P ≥ 0.21) over the 198-d finishing trial. Implanted heifers had greater hot carcass weight but lower marbling scores compared with CON heifers (P ≤ 0.04). In Exp. 2, there were no serial slaughter × implant treatment interactions for growth performance (P ≥ 0.23) or carcass characteristics (P ≥ 0.31). Final BW, fat thickness, and numerical YG increased linearly (P < 0.01), whereas ADG (P = 0.01) and G:F (P = 0.02) decreased linearly, with increasing days on feed. Implications and Applications: Hot carcass weight was increased by implanting strategy and increasing days on feed, but aggressive initial implants did not improve performance.
KW - feedlot
KW - heifers
KW - implant payout
KW - serial slaughter
UR - http://www.scopus.com/inward/record.url?scp=85099852551&partnerID=8YFLogxK
U2 - 10.15232/aas.2020-02013
DO - 10.15232/aas.2020-02013
M3 - Article
AN - SCOPUS:85099852551
VL - 37
SP - 41
EP - 51
JO - Applied Animal Science
JF - Applied Animal Science
SN - 2590-2873
IS - 1
ER -