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Selection for Body Weight in Chickens: Resource Allocations and Scaling

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dc.contributor.authorJambui, Michelleen
dc.contributor.committeechairSiegel, Paul B.en
dc.contributor.committeememberHonaker, Christa Fersten
dc.contributor.committeememberCline, Mark A.en
dc.contributor.departmentAnimal and Poultry Sciencesen
dc.date.accessioned2017-12-01T07:00:20Zen
dc.date.available2017-12-01T07:00:20Zen
dc.date.issued2016-06-08en
dc.description.abstractEvaluated were correlated responses to 54-generations of divergent selection for 8-week body weight (BW) and of BW at other ages and reproductive traits. Evaluated first was the influence of scaling on phenotypic responses to selection, phenotypic correlations of means and standard deviations, and unadjusted vs. standardized responses. Measured was BW at 4 (BW4), 8 (BW8), 24 (BW24), and 38 (BW38) weeks of age. Correlations between means and standard deviations were positive and greater in the LWS than HWS. Scaling masked the degree more than the pattern of response and was line specific with the magnitude of response greater in the LWS than HWS. While BW ratios across ages were not influenced by scaling in LWS, they were evident in HWS. Also measured were correlated responses of reproductive traits in selected and relaxed lines. Traits were age at first egg (AFE), body weight at first egg (WFE), their ratio (WAFE), and hen-day normal egg production (HDP). Although sexual maturity was delayed, the effect was more pronounced in the low than high weight lines. Selection for low BW decreased WFE, WAFE and HDP. Selection for high BW resulted in lower HDP, while WFE and WAFE were generally higher. Minimum AFE, WFE and WAFE in relation to sexual maturity were line specific. Opposition between relaxed and artificial selection resulted in a higher reproductive performance and fitness with relaxed than artificial selection. Overall, results demonstrate that correlated responses to long-term divergent selection were masked by scaling and negative correlated reproductive responses.en
dc.description.degreeMaster of Scienceen
dc.format.mediumETDen
dc.identifier.othervt_gsexam:8051en
dc.identifier.urihttp://hdl.handle.net/10919/80905en
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectSelectionen
dc.subjectcorrelated responsesen
dc.subjectscalingen
dc.subjectReproductionen
dc.subjectchickensen
dc.titleSelection for Body Weight in Chickens: Resource Allocations and Scalingen
dc.typeThesisen
thesis.degree.disciplineAnimal and Poultry Sciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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