Session: Beef Species II: Growing and Finishing Systems

95 - Effects of Three Implant Programs on Growth Performance, Carcass Outcomes, and Weekly Activity Minutes of Finishing Steers Fed Different Days on Feed

Friday, July 16, 2021

2:00 PM – 2:15 PM EST

Location: Kentucky International Convention Center (KICC), M101 & 102

Presenting Author(s)

Socorro L. Martinez, Masters Student

Graduate Assistant Researcher
West Texas A&M University
Canyon, Texas

PDF Slides and Audio

Author(s)

AW

Alyssa B. Word, PhD

Cactus Feeders
Amarillo, Texas
BH

Ben P. Holland, PhD, MBA, PAS

Director of Business Development and Operations Analysis
Cactus Feeders
Canyon, Texas
KK

Kendall Karr

Cactus Feeders
Amarillo, Texas
JH

John P. Hutcheson

Merck Animal Health
Madison, New Jersey
LW

Lee-Anne J. Walter

Merck Animal Health
Madison, New Jersey
JR

John Richeson, n/a

Associate Professor of Animal Science
West Texas A&M University
Canyon, Texas
TL

Ty E. Lawrence

Professor of Animal Science
West Texas A&M University
Canyon, Texas
KS

Kendall L. Samuelson, n/a

Assistant Professor
West Texas A&M University
Canyon, Texas

This study evaluated the effects of a single slow-release implant compared to two re-implant programs administered at either 120 days on feed (DOF) or 80 days from harvest on performance, carcass characteristics, and activity of serially harvested feedlot cattle. Using a randomized complete block design, steers (n = 4,680) were randomly assigned to 72 pens and 1 of 12 treatments in a 3 × 4 factorial arrangement. Treatments were either a slow-release implant (SR), an initial slow-release implant followed by re-implant at 120 DOF (SR+RI-120), or an initial slow-release implant followed by re-implant 80 days from harvest (SR+RI-80) administered to cattle harvested at 166, 180, 194, or 208 DOF. A 3-axis accelerometer ear-tag was used in a subset (n =1,080) of animals to quantify rumination time and activity. No interactions (P ≥ 0.09) were observed for implant × DOF. Implant did not affect (P ≥ 0.25) final BW, ADG, or DMI, but re-implanted steers had a greater (P < 0.01) G:F ratio than SR. Re-implanted steers also had greater (P ≤ 0.03) HCW, dressed yield, and ribeye area, but less (P < 0.01) backfat, marbling, and empty body fat (EBF) compared to SR. Re-implanted steers had less (P < 0.01) choice and yield grade 4 and 5 carcasses than SR steers. As DOF increased, HCW, dressed yield, backfat, marbling, and EBF increased linearly (P < 0.01). The percentage of choice and yield grade 4 and 5 carcasses also increased (P < 0.01) linearly with additional DOF. An implant × day effect (P < 0.01) for weekly activity minutes suggests re-implanted steers had greater activity after re-implant administration. Re-implanting within the payout period of a slow-release implant increases feed efficiency, HCW, dressed yield, and activity minutes, but decreases carcass fatness and reduces quality grade regardless of timing of secondary implant administration.