Title page for ETD etd-05312012-014508


Document Type Doctoral Thesis
Author Hope-Jones, Michelle
Email phoeka80@yahoo.com
URN etd-05312012-014508
Document Title Effects of dietary beta-agonist treatment, Vitamin D3 supplementation and electrical stimulation of carcasses on meat quality of feedlot steers
Degree PhD
Department Animal and Wildlife Science
Supervisor
Advisor Name Title
Dr P E Strydom Co-Supervisor
Prof E C Webb Supervisor
Keywords
  • meat quality
  • beta-agonist treatment
Date 2012-04-19
Availability unrestricted
Abstract
In this study, 20 young steers received no beta-adrenergic agonist (C), 100 animals all received zilpaterol hydrochloride, with 1 group only receiving zilpaterol (Z) while the other 4 groups received zilpaterol and vitamin D3 at the following levels and durations before slaughter: 7 million IU Vit D3 /animal/day for 3 days (3D7M); 7 million IU Vit D3/animal/day for 6 days (6D7M); 7 million IU Vit D3/animal/day for six days with 7 days no supplementation (6D7M7N) and 1 million IU Vit D3/animal/day for 9 days (9D1M). Left carcass sides were electrically stimulated (ES) and the right side not electrically stimulated (NES). Samples were aged for 3 or 14 days post mortem. Parameters included Warner Bratzler shear force (WBSF), myofibril filament length (MFL), sarcomere length and calpastatin and calpain enzyme activities. For drip loss and instrumental colour measurements, samples were analysed fresh (1 day post mortem) or vacuum-aged for 14 days post mortem.

Both ES-treatment and prolonged aging reduced WBSF (P < 0.001). Treatments 6D7M, 6D7M7N and Z remained significantly tougher than C (P < 0.001), while 3D7M and 9D1M improved WBSF under NES conditions. ES was shown to be more effective at alleviating beta-adrenergic agonist induced toughness than high vitamin D3 supplementation. Aging increased drip loss, lightness, redness and yellowness while ES increased drip loss. In general, Z showed increased drip loss, lighter meat, and reduced redness. Vitamin D3 supplementation could not consistently overcome the adverse effects of zilpaterol hydrochloride in feedlot steers.

2011 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Hope-Jones, M 2011, Effects of dietary beta-agonist treatment, Vitamin D3 supplementation and electrical stimulation of carcasses on meat quality of feedlot steers, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-05312012-014508/ >

D12/4/458/ag

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