Ractopamine Hydrochloride and Estradiol + Trenbolone Acetate Implants Alter Myogenic mRNA, <i>β</i>-Adrenergic Receptors, and Blood Metabolites  

作　　者：T. L. Harris Z. K. Smith F. R. B. Ribeiro M. A. Jennings G. J. Vogel B. J. Johnson T. L. Harris;Z. K. Smith;F. R. B. Ribeiro;M. A. Jennings;G. J. Vogel;B. J. Johnson(Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, USA;Elanco Animal Health, Greenfield, Indiana, USA;Department of Animal Science, South Dakota State University, Brookings, South Dakota, USA;Phytobiotics North America LLC, Cary, North Carolina, USA;Elanco Animal Health, Greenfield, Indiana, USA)

机构地区：[1]Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, USA [1]Elanco Animal Health, Greenfield, Indiana, USA [2]Department of Animal Science, South Dakota State University, Brookings, South Dakota, USA [3]Phytobiotics North America LLC, Cary, North Carolina, USA [4]Elanco Animal Health, Greenfield, Indiana, USA

出　　处：《Open Journal of Animal Sciences》2020年第3期447-467,共21页动物科学期刊（英文）

摘　　要：Two commonly used growth promotants in the United States beef industry are <em>β</em>-agonists and anabolic steroid hormones. Each has been shown to increase lean muscle deposition in cattle provided treatments of each growth technology, but much is still unknown of how steroidal implants and <em>β</em>-agonists work in combination. It was our goal to determine the effect of implant strategy and <em>β</em>-agonist administration in beef feedlot heifers (n = 264). A 3 × 2 factorial randomized complete block design was used with 2 levels of OPT and 3 different durations of terminal implant (TI) windows for a total of 6 treatment groups with 9 replications. Terminal implants (20 mg estradiol/200 mg trenbolone acetate implant, Component TE-200) were provided to heifers 140 d from slaughter (TI140), 100 d from slaughter (TI100), or 60 d from slaughter (TI60). Animals receiving the later two TI being first implanted on day 0 (8 mg estradiol/80 mg trenbolone acetate implant, Component TE-IH). The second treatment of the cattle received was the orally active beta adrenergic agonist, ractopamine-hydrochloride (RH) in the form of Optaflexx<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">&#174;</span>(OPT;0 (NO) or 200 (YES) mg/hd<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>d^-1) over the final 28 days of the trial. Thirty animals were subjected to longissimus muscle (LM) biopsies on d 0, 40, 80, 112, and at slaughter on d 140 to view mRNA levels of myogenic related genes and protein quantities of the <em>β</em>1-adrenergic receptor (<em>β</em>1 AR) and <em>β</em>2-adrenergic receptor (<em>β</em>2 AR). On the same days, blood samples were taken from 108 animals to assess changes in plasma blood urea nitrogen (BUN), non-esterified fatty acids (NEFA) and progesterone due to treatments. Relative mRNA levels of myosin heavy chain IIX (MHC IIX), AMPKα, and IGF-I were increased (<em>P</em> < 0.05) in aniTwo commonly used growth promotants in the United States beef industry are <em>β</em>-agonists and anabolic steroid hormones. Each has been shown to increase lean muscle deposition in cattle provided treatments of each growth technology, but much is still unknown of how steroidal implants and <em>β</em>-agonists work in combination. It was our goal to determine the effect of implant strategy and <em>β</em>-agonist administration in beef feedlot heifers (n = 264). A 3 × 2 factorial randomized complete block design was used with 2 levels of OPT and 3 different durations of terminal implant (TI) windows for a total of 6 treatment groups with 9 replications. Terminal implants (20 mg estradiol/200 mg trenbolone acetate implant, Component TE-200) were provided to heifers 140 d from slaughter (TI140), 100 d from slaughter (TI100), or 60 d from slaughter (TI60). Animals receiving the later two TI being first implanted on day 0 (8 mg estradiol/80 mg trenbolone acetate implant, Component TE-IH). The second treatment of the cattle received was the orally active beta adrenergic agonist, ractopamine-hydrochloride (RH) in the form of Optaflexx<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">&#174;</span>(OPT;0 (NO) or 200 (YES) mg/hd<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>d^-1) over the final 28 days of the trial. Thirty animals were subjected to longissimus muscle (LM) biopsies on d 0, 40, 80, 112, and at slaughter on d 140 to view mRNA levels of myogenic related genes and protein quantities of the <em>β</em>1-adrenergic receptor (<em>β</em>1 AR) and <em>β</em>2-adrenergic receptor (<em>β</em>2 AR). On the same days, blood samples were taken from 108 animals to assess changes in plasma blood urea nitrogen (BUN), non-esterified fatty acids (NEFA) and progesterone due to treatments. Relative mRNA levels of myosin heavy chain IIX (MHC IIX), AMPKα, and IGF-I were increased (<em>P</em> < 0.05) in ani

关 键 词：β-Agonist β-Receptor Muscle Hypertrophy Myogenic mRNA Ractopamine Hydrochloride Steroid Hormones 

分 类 号：R73[医药卫生—肿瘤]