Genetic response to index selection for the improvement of egg production efficiency in layer-type chickens

dc.contributor.author Singh, Harpal
dc.contributor.department Animal Science
dc.date 2018-08-15T04:24:17.000
dc.date.accessioned 2020-07-02T06:06:34Z
dc.date.available 2020-07-02T06:06:34Z
dc.date.copyright Fri Jan 01 00:00:00 UTC 1982
dc.date.issued 1982
dc.description.abstract <p>Recording individual feed consumption in layer-type chickens is costly. For this reason, feed record information in most commercial breeding programs is omitted. The present study focuses on the evaluation of feed records to improve egg production efficiency in two populations of Leghorns. From four generations of index selection based on body weight, egg mass and feed consumption information, sexual maturity was delayed, egg size and daily egg mass output increased and feed efficiency (egg mass/feed consumption) improved. On the other hand, selection on an index containing information only on body weight and egg mass, increased body weight, egg weight, daily egg mass and feed consumption, but it failed to improve feed efficiency. The preliminary results, therefore, indicate that feed record information aids in improving the efficiency of feed utilization;The selection responses obtained in two different populations of Leghorns were frequently inconsistent for several traits. This may have been due to an incorrect choice of the economic value constant for body weight in the selection indexes used in the two initial generations of selection. A contributing factor might have been a poor choice of parameter estimates taken from the literature which were needed to solve the index normal equations. It is concluded that to establish superiority of an index containing feed record information, additional generations of the selection experiment would be required. Data of the latest generations available might then be used to obtain better estimates of parameters needed to solve the index equations.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/8387/
dc.identifier.articleid 9386
dc.identifier.contextkey 6333745
dc.identifier.doi https://doi.org/10.31274/rtd-180813-7981
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/8387
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/81369
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/8387/r_8307790.pdf|||Sat Jan 15 02:10:29 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 Genetic response to index selection for the improvement of egg production efficiency in layer-type chickens
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 85ecce08-311a-441b-9c4d-ee2a3569506f
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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