Comparison of expected and actual progeny growth differences in crossbred calves

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dc.contributor.authorMahrt, Garry Sonnen
dc.contributor.committeechairNotter, David R.en
dc.contributor.committeememberEller, Arthur L. Jr.en
dc.contributor.committeememberPearson, Ronald E.en
dc.contributor.committeememberVinson, William E.en
dc.contributor.departmentAnimal Scienceen
dc.date.accessioned2014-03-14T21:49:56Zen
dc.date.adate2012-11-17en
dc.date.available2014-03-14T21:49:56Zen
dc.date.issued1987-06-05en
dc.date.rdate2012-11-17en
dc.date.sdate2012-11-17en
dc.description.abstractThe growth performance of Angus-Polled Hereford F<sub>1</sub> calves was compared to the expected progeny differences (EPD) estimated by the American Polled Hereford Association to evaluate the usefulness of EPD estimates for improving commercial beef production. Polled Hereford sires were selected from the high accuracy sires listed in the American Polled Hereford Association's sire summary. Four types of sires were used: 1) Sires with high yearling weight and high maternal EPD's; 2) Sires with high yearling weight and low maternal EPDâ s; 3) Sires with low yearling weight and high maternal EPD's; and 4) Sires with low yearling weight and low maternal EPD's. The resulting progeny were weighed at birth, approximately 135 d, weaning and approximately 1 yr. Hip heights were also measured at weaning. Linear regressions of progeny performance on EPD indicated that birth and yearling weights were accurately predicted by their respective EPD estimates. Weight and height at weaning were not accurately predicted by weaning weight EPD. Partial regressions of progeny performance on yearling weight and maternal EPD's were also calculated. Regression of progeny performance on yearling weight EPD resulted in .16 ±.09 kg/kg for 135-d weight, .28 ± .09 kg/kg for weaning weight, .073 ± .020 cm/kg for weaning hip height and .93 ±.19 kg/kg for yearling weight. Comparable regression values for maternal EPD were .44 ± .18 kg/kg, .31 ± .17 kg/kg, .100 ± .040 cm/kg and .22 ± .36 kg/kg for 135-d, weaning weight, weaning hip height and yearling weight, respectively. These results indicate that maternal EPD values predicted some differences in preweaning growth that were not predicted by yearling weight EPD. The progeny performance data was also used to calculate independent EPD estimates for birthweight, weaning weight, and yearling weight. Correlations between these EPD estimates and those made by the American Polled Hereford Association were .49 for birthweight, .26 for weaning weight and .66 for yearling weight. The low correlation between weaning weight EPD estimates was significantly below expectation and indicates that the American Polled Hereford Association estimates were inadequate for predicting preweaning growth differences in these crossbred calves.en
dc.description.degreeMaster of Scienceen
dc.format.extentvii, 86 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-11172012-040158en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-11172012-040158/en
dc.identifier.urihttp://hdl.handle.net/10919/45794en
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1987.M343.pdfen
dc.relation.isformatofOCLC# 16751591en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1987.M343en
dc.subject.lcshBeef cattle -- Breedingen
dc.subject.lcshCalvesen
dc.titleComparison of expected and actual progeny growth differences in crossbred calvesen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineAnimal Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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