The effect of non-genetic factors on milk yield and composition of Red Dane cattle in Zimbabwe

摘要

Astudywascarriedouttoestablishnongeneticfactorsaffectingmilk,butterfatandproteinyieldsinZimbabweanRedDanecattle.Atotalof1325unedited305-daylactationrecordswereobtainedfromZimbabweLivestockIdentificationTrustherd,withcowscalvingintheperiod2002#8211;2006.TheHendersonTypeIIIsumofsquaresinGenstatedition14programwasused.nbsp;Parity,daysinmilk,yearofcalvingandageofcalvinghadsignificanteffects(P0.05)onmilk,fatandproteinyield;milkyield;proteinandfatyield;andmilkandproteinyieldrespectively.Anincreaseinparityresultedinanincreaseinmilkyieldandcompositionuptoparity4andstarteddeclininginparity5.Anincreaseindaysinmilkalsoresultedinanincreaseinmilkyieldwherebythemilkyieldincreasedatadecliningrateasfrom350daysto550days.Milkyieldandcompositiondeclinedin2005andtherewasadeclineinproteinyieldfrom2006to2009.Lastly,milkandproteinyieldresultedinagradualincreaseupto58monthsfollowedbyadecliningtrendupto103months.Monthofcalvinganddaysdrydidnothavesignificanteffects(P0.05)onmilkyieldandcompositionofRedDanecattleinZimbabwe.Thestudyshowedthatnon-geneticfactorshaveasignificanteffectonmilkyieldandcompositionofRedDanecattleinZimbabwe.