Genetic parameters for growth traits in N’Dama cattle under tsetse challenge in the Gambia

摘要

nbsp;HeritabilitiesandcorrelationsforgrowthtraitsinN'Damacattleundertsetsechallengewereestimatedusingananimalmodel.Animalswerebornandweanedinalowtomediumtsetsechallengeareaand,afterweaningat12monthsofage,theyweretransportedtoahightsetsechallengeareauntilthreeyearsofage.Measurementsincludedbodyweightandgrowthrateduringseasonsfrom12to36monthsofage.Twoseasonsweredefined:thedryseasonfromNovembertoJunerepresentingtheperiodoffeedshortageandlowtsetseflydensity;andthewetseasonfromJunetoNovemberwheresufficientfeedwasavailableandthetsetsedensitywasthehighest.nbsp;Heritabilitiesforbodyweightrangedfrom0.28forbodyweightat36monthsofageto0.48forbodyweightat15monthsofage.Forgrowthrate,theheritabilitywas0.09duringthedryseasonand0.15duringthewetseason.Geneticcorrelationsofbirthweightwithbodyweightat12and15monthsofageweremoderatelyhigh(0.49and0.51,respectively).Geneticcorrelationsbetweenmostbodyweightsandgrowthratesduringseasonsrangedfrom#8211;0.40to0.80.Thegenetictrendduetotheselectionprogrammewashighestforbodyweightat36monthsofagefrom1994to2004.Forgrowthtraits,anincreasinggenetictrendwasobservedingrowthbetween15and36monthsofageandingrowthduringthedryseasonfrom12to36monthsofage.nbsp;Itwasconcludedthatselectionforgrowthshouldfocusongrowthduringdryandwetseasons.