Effect of breed, season, year and parity on reproductive performance of dairy cattle under smallholder production system in Bukoba district, Tanzania

摘要

Astudywasconductedtoevaluatetheeffectsofbreedlevelandnon-geneticfactorsonreproductiveperformanceofdairycattleundersmallholderproductionsystem.ThestudyfocusedonassessingthereproductiveefficiencyofdairycattleundersmallholderfarmsinBukobadistrict,Tanzania.Dataonageatfirstcalving(AFC),calvingtofirstserviceinterval(CFSI),numberofservicesperconception(NSC),daysopen(DO)andcalvinginterval(CI)werecollectedfromKageraDairyDevelopmentTrust(KADADET)inBukobadistrict.GeneralLinearmodelsprocedureofStatisticalAnalysisSystem(SAS)computersoftwarewasusedtoanalysethedata.Thefixedeffectsconsideredintheanalysesweregeneticgroup,parity,seasonandperiodofbirthorofcalving.nbsp;TheoverallmeanforAFCwas35.1+9.7monthswithacoefficientofvariationof18.6%,forCFSIitwas196.95+1.8dayswithacoefficientofvariationof20%whilethemeanforNSCwas1.66+0.0withacoefficientofvariationof21%.Further,themeanDOwas205.2+2.6dayswithcoefficientofvariationof19%,andCIaveraged480.4+2.4dayswithacoefficientofvariationof22%.AFCwassignificantlyaffectedbyperiodofbirth(P0.001),levelofexoticblood(P0.05)andseasonofbirth(P0.05).GeneticgroupsignificantlyinfluencedCFSI,NSC,CI(P0.05)andDO(P0.001).F1crossesperformedbetterthanhigh-gradesinallthetraitswith34.6monthsofAFC,171daysofCFSI,182daysofDO,and455daysofCI.SeasonofcalvingsignificantlyinfluencedCFSI(P0.01),CI(P0.001),NSCandDO(P0.05).Cowscalvinginthelongrainseasonweresuperiorwith17daysofCFSI,21daysopenandhadshorter(by27days)CIthanthosecalvinginthelongdryseason.ParityandperiodofcalvingsignificantlyaffectedCFSI(P0.05andP0.001),NSC(P0.05),DO(P0.01andP0.001),CI(P0.05andP0.001)respectively.Forthesetraits,performancewasimprovingbyadvancementinageofcows.Milkyieldinthefirst100daysoflactationhadnosignificantinfluenceonpost-calvingreproductivetraits.nbsp;ItwasconcludedthatreproductiveperformancewasbestinthelongrainseasonandthatwithrespecttoreproductivetraitsF1crosseswerebetterthanhighgradesinBukobadistrict.