Impacts of cytoplasmic inheritance on production traits of dairy cattle

dc.contributor.advisor A. E. Freeman Boettcher, Paul
dc.contributor.department Animal Science 2018-08-23T14:48:51.000 2020-06-30T07:08:25Z 2020-06-30T07:08:25Z Sun Jan 01 00:00:00 UTC 1995 1995
dc.description.abstract <p>The importance of effects of cytoplasmic inheritance on milk production traits of dairy cattle was examined. Three approaches were taken;Effects of cows' maternal lineages on production were estimated by using animal models. Maternal lineages were established on the basis of cows' earliest recorded female ancestors. Data were 6054 records from 2264 cows from North Carolina and Iowa research herds. First parity records from North Carolina, all records from North Carolina, and all records pooled from Iowa and North Carolina were analyzed by separate procedures. Both yield and milk composition traits were studied. Significant associations with maternal lineages were detected for milk fat percentage and milk energy concentration. Variance components for maternal lineages were also estimated. Maternal lineages accounted for 2.9% of phenotypic variance in fat percentage found in the pooled records. Otherwise, 1% or less of the variance in any trait was associated with maternal lineages;The sequences of the displacement-loop and ribosomal RNA genes of mitochondrial DNA were determined for cows from North Carolina and Iowa herds. Effects of polymorphism in these regions of DNA on production traits were estimated by using animal models that included regression coefficients for sites of polymorphism. Significant associations between phenotype and mitochondrial DNA polymorphism were detected at several sites for most traits. Without exception, when a significant effect existed, the wild-type sequence was favorable to the mutant (less common) type;Simulation was used to determine impacts of ignoring cytoplasmic effects on estimation of variance components, accuracy of genetic evaluations, genetic response, and selection of bull dams. Three levels of maternal lineage variance were considered: 2.5, 5, and 10% of total variance. Failure to account for cytoplasmic effects caused reduced selection accuracy and genetic response. Sizes of progeny test programs can be reduced without sacrificing response if cytoplasmic effects are correctly considered. Impacts increase linearly as size of cytoplasmic effects increase. Including maternal lineage effects in a genetic evaluation model when true effects are zero causes reduced accuracy and genetic response. No practical differences were observed whether maternal lineage effects were considered fixed versus random.</p>
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dc.identifier archive/
dc.identifier.articleid 11881
dc.identifier.contextkey 6423293
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/10882
dc.language.iso en
dc.source.bitstream archive/|||Fri Jan 14 18:29:55 UTC 2022
dc.subject.disciplines Agriculture
dc.subject.disciplines Animal Sciences
dc.subject.disciplines Genetics
dc.subject.keywords Animal science
dc.subject.keywords Animal breeding
dc.title Impacts of cytoplasmic inheritance on production traits of dairy cattle
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 85ecce08-311a-441b-9c4d-ee2a3569506f dissertation Doctor of Philosophy
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