A breeding goal for South African Holstein Friesians in terms of economic weights in percentage units

Abstract

In South Africa the exact breeding goal for Holstein Friesians still needs to be determined. This means that the traits, which should be most important in selection have to be identified. One method to identify these traits could be to calculate economic weights for production and functional traits. Economic weights calculated in absolute units cannot be compared because some traits are measured in different units. The objective of this study was therefore the calculation of economic weights for production and functional traits, in percentage units, to make a comparison between traits possible. The production traits were milk, butterfat, protein and lactose yield and the functional traits included survival rate, feed efficiency, live weight and calving interval. The study used a simulation model to calculate economic weights. This model included three production enterprises classified according to the production level of the herds. The results show that for all three the production enterprises milk yield is potentially the most important trait to improve in selection, with the second trait being feed efficiency followed by live weight. The results were confirmed by constructing a selection index, including milk yield and live weight, showing that economic improvement with a selection index is about 25% more efficient than direct selection for milk yield alone.In Suid-Afrika is die presiese teeldoelwit vir Holstein Friese nog nie bepaal nie. Dit beteken dat die eienskappe wat die belangrikste behoort te wees in seleksie nog geidentifiseer moet word. Berekening van ekonomiese gewigte vir produksie en funksionele eienskappe is een manier om hierdie eienskappe te identifiseer. Met ekonomiese gewigte in absolute eenhede is 'n vergelyking tussen die eienskappe nie moontlik nie, omdat eienskappe gemeet word in verskillende eenhede. Die doelwit van hierdie studie was die berekening van ekonomiese gewigte in persentasie eenhede om 'n vergelyking van die eienskappe moontlik te maak. Die produksie-eienskappe in die studie was melk-, bottervet-, proteien- en laktose opbrengs en die funksionele eienskappe het oorlewingstempo, voerdoeltreffendheid, liggaamsmassa en kalfinterval ingesluit. Die studie het 'n simulasiemodel gebruik om ekonomiese gewigte te bereken met die insluiting van drie produksiesisteme wat geklassifiseer is volgens die produksievlak van die kudde. Die resultate toon dat vir al drie die produksie-sisteme melkopbrengs potensieel die belangrikste eienskap is om te verbeter in seleksie, met voerdoeltreffendheid die tweede belangrikste eienskap gevolg deur liggaamsmassa. Om die resultate te staaf is 'n seleksie-indeks bereken, wat melkopbrengs en liggaamsmassa insluit en getoon het dat ekonomiese vordering ongeveer 25% meer effektief is met indeks-seleksie as seleksie slegs vir melkopbrengs.