Sequential feeding of β-adrenergic agonists to realimentated cull cows

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Show simple item record Weber, Melissa Jean 2011-01-04T18:15:01Z 2011-01-04T18:15:01Z 2011-01-04
dc.description.abstract Sixty cull cows were utilized to investigate the effects of feeding a single or sequence of β-adrenergic agonists (β-AA) on performance, mRNA expression, carcass traits, economics, meat palatability, and ground beef color. Treatments included: 1) concentrate fed for 74 d (C); 2) concentrate fed for 49 d then supplemented with ractopamine-HCl for 25 d (RH); 3) concentrate fed for 51 d then supplemented with zilpaterol-HCl for 20 d (ZH); 4), concentrate fed for 26 d then supplemented with RH for 25 d followed by ZH for 20 d (RH + ZH). No differences existed among treatments for performance or carcass characteristics. However, cows supplemented with ZH (ZH and RH + ZH treatments) had increased LM areas (P = 0.18) compared to control and RH cows. Sequential feeding of RH followed by ZH had no influence on β2-adrenergic receptor (AR) mRNA expression. However, β2-AR mRNA was increased (P < 0.05) in the RH and ZH treatments when RH or ZH was supplemented during the last 20 to 25 d of feeding. Myosin heavy chain (MHC) Type IIa mRNA decreased (P < 0.05) from d 24 to 51 in all cows, while MHC-IIx increased (P < 0.05) in the ZH and RH + ZH treatments during ZH supplementation. No differences were observed in ground beef color shelf-life among treatments. Effects of β-AA supplementation on meat palatability varied among muscles. Infraspinatus steaks had improved (P < 0.05) WBSF values with β-AA supplementation. Psoas major steaks from the RH + ZH treatment were rated as more tender than steaks from all other treatments. Non-enhanced LM steaks from ZH supplemented cows had higher (P = 0.12) WBSF values along with decreased (P < 0.0001) percentages of degraded desmin compared to control and RH cows. Collagen solubility of the LM was increased with ZH supplementation compared to RH and control cows. Enhancement of steaks with 0.1 M calcium lactate improved LM tenderness of β-AA supplemented cows. Implanting and feeding cull cows for 74 d, regardless of β-AA supplementation, added value by transiting cows from a “cull” cow to “white” cow market. en_US
dc.language.iso en_US en_US
dc.publisher Kansas State University en
dc.subject realimentation en_US
dc.subject cull cows en_US
dc.subject ractopamine-HCl en_US
dc.subject zilpaterol-HCl en_US
dc.subject carcass and meat traits en_US
dc.subject β2-adrenergic receptors en_US
dc.title Sequential feeding of β-adrenergic agonists to realimentated cull cows en_US
dc.type Dissertation en_US Doctor of Philosophy en_US
dc.description.level Doctoral en_US
dc.description.department Department of Animal Sciences and Industry en_US
dc.description.advisor Michael E. Dikeman en_US
dc.subject.umi Agriculture, Animal Culture and Nutrition (0475) en_US
dc.subject.umi Agriculture, Food Science and Technology (0359) en_US 2011 en_US May en_US

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