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Effect of ractopamine hydrochloride on environmental gas emissions, growth performance, and carcass characteristics in feedlot steers

Authors
  • Ross, Elizabeth G1
  • Ball, Jase J2
  • Werth, Samantha J1
  • Mejia-Turcios, Sebastian E1
  • Zhao, Yongjing3
  • Pan, Yuee1
  • Taube, Patrick C2
  • Meinert, Todd R2
  • Van Engen, Nicholas K4
  • Mitloehner, F M1
  • 1 Department of Animal Science, University of California, Davis, Davis, CA 95616 , (United States)
  • 2 Zoetis, Inc., Kalamazoo, MI 49007 , (United States)
  • 3 Air Quality Research Center, University of California, Davis, Davis, CA 95616 , (United States)
  • 4 Johnson Research, LLC., Parma, ID 83660 , (United States)
Type
Published Article
Journal
Journal of Animal Science
Publisher
Oxford University Press
Publication Date
May 03, 2021
Volume
99
Issue
5
Identifiers
DOI: 10.1093/jas/skab143
PMID: 33939826
PMCID: PMC8153700
Source
PubMed Central
Keywords
Disciplines
  • AcademicSubjects/SCI00960
License
Unknown

Abstract

With a growing global population and increased environmental concerns around animal agriculture, it is essential to humanely maximize animal performance and reduce environmental emissions. This study aims to determine the efficacy of feeding ractopamine hydrochloride ( RAC ), an orally active, β 1-adrenergic agonist ( β 1 AA ), to feedlot steers in the last 42 d of finishing to reduce ammonia (NH3) emissions and improve animal performance. A randomized complete block design was used to allocate 112 Angus and crossbred Angus steers (initial body weight [ BW ] = 566.0 ± 10.4 kg) to 8 cattle pen enclosures. Pens ( n = 4 per treatment, 14 steers per pen, and 56 steers per treatment) were randomly assigned to one of two treatments: 1) CON; finishing ration containing no RAC, 2) RAC; finishing ration containing 27.3 g/907 kg dry matter ( DM ) basis RAC. Steers were weighed on day −1 and 0 before treatment and day 14, 28, and 42 during treatment. Treatment rations were mixed and delivered daily by masked personnel. Measured emissions included NH3, nitrous oxide (N2O), methane (CH4), hydrogen sulfide (H2S), and carbon dioxide (CO2). The primary response variables assessed were emissions standardized by live weight ( LW ) and hot carcass weight ( HCW ). Steers were harvested on day 43 and carcass data were collected on day 43 and 44. Steers fed RAC reduced NH3 emissions by 17.21% from day 0 to 28 ( P = 0.032) and tended to reduce NH3 from day 0 to 42 by 11.07% ( P = 0.070) vs. CON. When standardized for LW, NH3 was reduced by 23.88% from day 0 to 14 ( P = 0.018), 17.80% from day 0 to 28 ( P = 0.006), and 12.50% for day 0 to 42 ( P = 0.027) in steers fed RAC vs. CON. Steers fed RAC had 14.05% ( P = 0.013) lower cumulative NH3 emissions when standardized by HCW vs. CON. Feeding RAC to Steers reduced H2S by 29.49% from day 0 to 14 ( P = 0.009) and tended to reduce H2S over day 0 to 28 by 11.14% ( P = 0.086) vs. CON. When H2S emissions were standardized for LW, RAC fed steers had a 28.81% reduction from day 0 to 14 ( P = 0.008) vs. CON. From day 0 to 42 the RAC fed steers tended to have a 0.24 kg/d greater average daily gain ( ADG ) ( P = 0.066) and tended to eat 4.27% less ( P = 0.069) on a DM basis vs. CON. The RAC fed steers had a 19.95% greater gain to feed ratio ( G:F ) compared to CON ( P = 0.012). Steers fed RAC had an average of 12.52 kg greater HCW ( P = 0.006) and an increase of 1.93 percentage units in dressing percent ( DP ) ( P = 0.004) vs. CON. Ractopamine is an effective medicated feed additive for reducing NH3 and improving end product performance through HCW yields.

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