Sources of variation and genetic analysis of fertility of maiden ewes in an out-of-season management system

摘要

Thisstudyinvestigatedthesourcesofvariationandthegeneticprofileofthespringfertilityof18monthsoldBarbarinemaidenewes.Thetraitwascodedas1or0formaidenewesthatdid,ordidnot,lambinfall,respectively.Datawere3314maidenewerecordsdaughtersof408sirestakenover12consecutiveyearsand9flockskeptatthepilotsheepfarmofJebibinaandSaouafinsemiaridTunisia.Fullpedigreewasalsoavailableformostofthesiresanddamsofthemaidenewes.AveragespringfertilityofBarbarinemaidenewesinthestudiedenvironmentis0.85±0.35withsignificanteffectsoftheyear,flockandtheaveragedailygrowthbetween10and30days(ADG10-30).Thesesourcesofvariationwereincludedinthelinearanimalmodeltoestimategeneticparameters.Heritabilityestimateofspringfertilitywas0.05±0.02whilegeneticcorrelationbetweenspringfertilityandADG10-30was-0.29.Therewasaverycloseandpositive(P0.001)relationshipbetweenthesires#8217;EBVforthestudiedtraitandtheaveragefertilityoftheirdaughters.The20%toprankedsireshadamean0.97springfertilityoftheirdaughtersincomparisontoonly0.75forthe20%bottomrankedsires.Theresultsobtainedinthisstudyshowthatdirectselectiononspringfertilityofmaideneweswouldgeneratenegligiblegeneticprogress.Theyalsohighlighttheimportanceofconsideringthesires#8217;EBV#8217;sinthedevelopmentofabreedingplanfortheBarbarinesheepbreed.nbsp;