The Effect of Inbreeding on Lifetime Performance of Dairy Cattle

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dc.contributor.authorSmith, Lori A.en
dc.contributor.committeechairCassell, Bennet G.en
dc.contributor.committeememberPearson, Ronald E.en
dc.contributor.committeememberMcGilliard, Michael L.en
dc.contributor.committeememberVinson, William E.en
dc.contributor.departmentDairy Scienceen
dc.date.accessioned2014-03-14T20:51:00Zen
dc.date.adate1997-01-27en
dc.date.available2014-03-14T20:51:00Zen
dc.date.issued1997-01-27en
dc.date.rdate1997-01-27en
dc.date.sdate1998-07-19en
dc.description.abstractData for this study were age-adjusted linear scores on all cows scored between 1980 and 1993. Lifetime production information on these cows and their herdmates was used to calculate Relative Net Income adjusted for opportunity cost (RNIOC) for the 2,249,835 cows with an 84 month herdlife opportunity. The effect of inbreeding was analyzed using both a fixed and animal model, with little difference in results. Inbreeding depressed RNIOC by $12.69 in a fluid market and $11.53 in a manufacturing market per 1% increase in inbreeding. Addition of somatic cell information in the profit function had little effect. Heritabilities of profit functions were .16 and .14 for a fluid and manufacturing market, respectively. Animal model estimates of inbreeding depression were +.16 days, -6.7 days and -5.1 days for age at first freshening (AFF), days of productive life (DPL) and days in milk (TDIM), respectively. Inbreeding decreased first lactation mature equivalent milk, fat, and protein by 23.7 kg, .85 kg, and .76 kg, respectively and lifetime milk, fat, and protein production by 176.9 kg, 6.4 kg, 5.6 kg, respectively per 1% increase in inbreeding. Inbreeding had little effect on conformation traits. Effects of inbreeding were cumulative, exacting a larger effect on lifetime profit functions than on individual traits, when expressed as a percent of additive standard deviation. This study gives evidence that though not alarming, inbreeding has a deleterious effect on the lifetime performance of dairy cattle.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-175711241971540en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-175711241971540/en
dc.identifier.urihttp://hdl.handle.net/10919/36526en
dc.publisherVirginia Techen
dc.relation.haspartetd.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectinbreedingen
dc.subjectlifetime profiten
dc.subjectrelative net incomeen
dc.subjectopportunity costen
dc.titleThe Effect of Inbreeding on Lifetime Performance of Dairy Cattleen
dc.typeThesisen
thesis.degree.disciplineDairy Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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