566
Effects of technology use in feedlot production systems on feedlot performance and carcass characteristics

Wednesday, July 23, 2014: 2:00 PM
2104B (Kansas City Convention Center)
Casey L. Maxwell , Oklahoma State University, Stillwater, OK
Bryan C Bernhard , Oklahoma State University, Stillwater, OK
Charlotte F. O'Neill , Oklahoma State University, Stillwater, OK
Blake K. Wilson , Oklahoma State University, Stillwater, OK
Cody Hixon , Oklahoma State University, Stillwater, OK
Catherine Haviland , Oklahoma State University, Stillwater, OK
Andrew Grimes , Oklahoma State University, Stillwater, OK
Michelle Sarah Calvo-Lorenzo , Oklahoma State University, Stillwater, OK
Deborah L. VanOverbeke , Oklahoma State University, Stillwater, OK
Gretchen G. Mafi , Oklahoma State University, Stillwater, OK
Christopher J. Richards , Oklahoma State University, Stillwater, OK
D. L. Step , Oklahoma State University, Stillwater, OK
Ben P. Holland , Merck Animal Health, DeSoto, KS
Clinton R. Krehbiel , Oklahoma State University, Stillwater, OK
Recorded Presentation (mp4)
Abstract Text: The objectives of this study were to examine the effects of conventional feedlot production systems with and without the use of a β-adrenergic agonist compared to a natural production program on feedlot performance and carcass characteristics.  Natural crossbred beef steers (n = 336; initial BW = 379 ± 8 kg) were randomized to one of three treatments in a RCBD (14 steers/pen; 8 pens/treatment).  Treatments consisted of a natural treatment (NAT), a conventional treatment (CONV), and a conventional treatment with a beta-agonist (CONV-Z).  The NAT cattle received no growth promoting technologies. The CONV and CONV-Z cattle were implanted with 40 mg of estradiol and 200 mg of trenbolone acetate on d 0, and were fed 33 and 9 mg/kg of monensin and tylosin daily, respectively.  The CONV-Z cattle were fed zilpaterol hydrochloride at 6.76 mg/kg (90% DM basis) for the last 20 DOF.  There was no effect of treatment on DMI (P = 0.83), however CONV-Z steers gained 3.8% faster (1.64 vs. 1.58 kg/d; P < 0.01) and were 5.3% more efficient (0.160 vs. 0.152; P < 0.01) than CONV steers, and CONV steers gained 32.8% faster (1.58 vs 1.19 kg/d; P < 0.01) and were 26.7% more efficient (0.152 vs. 0.120; P < 0.01) than NAT steers. Hot-carcass weight was increased by 8 kg for CONV-Z steers compared to CONV steers (394 vs. 386 kg; P = 0.05) and 46 kg compared to NAT steers (394 vs. 348 kg; P < 0.01).  Fat thickness was less for CONV-Z compared to CONV cattle (1.10 vs 1.22 cm; P = 0.03), but not different from NAT (P > 0.05).  Longissimus muscle area was increased by 3.6 cm2 for CONV-Z steers compared to CONV steers (92.29 vs 88.67 cm2; P = 0.02) and 12.1 cm2 for CONV-Z steers compared to NAT steers (92.29 vs. 80.16 cm2; P < 0.01), resulting in a 17.9 percentage unit reduction in USDA YG 3 for CONV-Z steers compared to NAT steers (30.70 vs. 48.61%; P < 0.05).  There was no difference in marbling score for CONV steers compared to NAT steers (470 vs. 471; P = 0.99) however, CONV-Z steers had a lower marbling score compared to the other treatments (432; P < 0.01).  The results of this experiment show that CONV-Z and CONV production results in a significant improvement in feedlot performance and USDA Yield Grade, compared to NAT.

Keywords: conventional, beef cattle natural

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