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dc.contributor.authorBarrett, Nathaniel Wadeen_US
dc.date.accessioned2016-11-03T08:00:27Z
dc.date.available2016-11-03T08:00:27Z
dc.date.issued2016-11-02en_US
dc.identifier.othervt_gsexam:8986en_US
dc.identifier.urihttp://hdl.handle.net/10919/73369
dc.description.abstractCommercial laying hens are heavily selected for increased egg production, but little selection has occurred for resistance to extreme temperatures. The objective of the experiment was to determine the effects of a daily cyclic heat stress (HS) on performance, body temperature, egg quality, nitrogen corrected apparent metabolizable energy, and blood chemistry in laying hens at acute and chronic time points. In total, 407 pure line laying hen pullets (18 wk) were sourced from Hy-Line International and housed individually for the duration of the experiment. Feed intake, egg production, and body weights were significantly decreased while egg weight and feed efficiency increased due to HS exposure. All egg quality parameters except yolk weight were decreased by HS exposure, including Haugh unit, eggshell and albumen weights. Egg yolk weights were increased over the first 2 wk of HS before falling. Blood chemistry was affected by HS resulting in respiratory alkalosis likely caused by increased respiration and evaporative cooling. There was a decrease in the PCO2, an increase in pH and a reduction in iCa in the blood within 4 to 6 hours of HS when compared to pre-HS levels. The data indicate that the hens were negatively affected by HS and the response was different for acute and chronic time points. At the acute time point the changes to the hen's physiology were caused by altered blood chemistry, but after chronic exposure, the low feed intake seemed to influence the responses.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.rightsThis Item is protected by copyright and/or related rights. Some uses of this Item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).en_US
dc.subjectHeat stressen_US
dc.subjectlaying henen_US
dc.subjectperformanceen_US
dc.subjectblood chemistryen_US
dc.subjectegg qualityen_US
dc.titleThe Acute and Chronic Effects of a Cyclic Heat Stress on 24 to 28 Week Old Laying Hens on Performance, Egg Quality, Apparent Metabolizable Energy, and Blood Chemistryen_US
dc.typeThesisen_US
dc.contributor.departmentAnimal and Poultry Sciencesen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineAnimal and Poultry Sciencesen_US
dc.contributor.committeechairPersia, Michael E.en_US
dc.contributor.committeememberSchmidt, Carl J.en_US
dc.contributor.committeememberDalloul, Rami Alien_US


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