Dietary inclusion of virginiamycin to ameliorate the effect of heat stress on broilers

dc.contributor.advisorJansen van Rensburg, Christine
dc.contributor.emailluhandri@gmail.comen_ZA
dc.contributor.postgraduateVan der Walt, Luhandri
dc.date.accessioned2020-02-06T12:33:28Z
dc.date.available2020-02-06T12:33:28Z
dc.date.created2020-04-24
dc.date.issued2019
dc.descriptionDissertation (MSc)--University of Pretoria, 2019.en_ZA
dc.description.abstractHeat stress is a cause of great economic loss in poultry production throughout the world. Many methods have been researched to find a solution to alleviate the negative effects of heat stress. Methods include but are not limited to: adequate ventilation and facility orientation, the acclimation of birds to elevated temperatures, electrolyte and acid-base balance to maintain body fluid homeostasis, water management to aid in evaporative cooling, feed management by means of fasting and nutrition to ensure a balance diet during reduced intake and non-nutritive feed additives to improve performance. Previous research has shown that the inclusion of virginiamycin (VM) in poultry diets during periods of heat stress may improve growth rate, feed intake, feed conversion ratio, survivability and carcass weight. This was tested by conducting an experiment on 1408 male broilers. A randomised block design was used with 32 pens in each side of the house. Chicks were randomly assigned to four treatments with 16 replications, each containing 22 broilers. Data was statistically analysed as a randomised block design with the GLM model and mortality data by Chi-square. The broilers were subjected to a temperature profile which simulated a cyclic heat wave with high temperatures during the day and lower temperatures at night. From day 16 to 32, house temperature was gradually increased from 8:00-11:00 until the set maximum temperature of the profile was achieved and decreased at 18:00 to 24 °C. The control group received a diet without antibiotic growth promoters. The second group which was a positive control group received a diet with zinc bacitracin 15% (334 g/ton). The third group received a diet with VM (20 g/ton) in all feeding phases whilst the fourth group received VM (20 g/ton) in all feeding phases with exception of the post-finisher phase. Broiler performance, intestinal morphology and carcass and blood composition of birds were measured. The addition of VM to the feed of broilers subjected to heat stress had no significant (P<0.05) effect on body weight or carcass and blood composition. Mortality within the third and fourth group was significantly lower, both before and after the onset of high cyclic temperatures. Supplementation of VM could be beneficial to lower the mortality rate of birds subjected to heat stress.en_ZA
dc.description.availabilityUnrestricteden_ZA
dc.description.degreeMscen_ZA
dc.description.departmentAnimal and Wildlife Sciencesen_ZA
dc.identifier.citationVan der Walt, L 2019, Dietary inclusion of virginiamycin to ameliorate the effect of heat stress on broilers, Msc Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/73133>en_ZA
dc.identifier.otherA2020en_ZA
dc.identifier.urihttp://hdl.handle.net/2263/73133
dc.language.isoenen_ZA
dc.publisherUniversity of Pretoria
dc.rights© 2019 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.
dc.subjectUCTDen_ZA
dc.subjectAnimal scienceen_ZA
dc.titleDietary inclusion of virginiamycin to ameliorate the effect of heat stress on broilersen_ZA
dc.typeDissertationen_ZA

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