Direct and maternal variance component estimates for clean fleece weight, body weight and mean frbre diameter in the Grootfontein Merino stud

Abstract

Direct and maternal variance components and resulting heritabilities were estimated by DFREMl-procedures for clean fleece weight (CFW), body weight (BW) and mean fibre diameter (MFD) in the Grootfontein Merino stud. Direct heritabilities were estimated as 0.381, 0.289 and0.626 for BW, CFW and MFD, respectively. The maternal additive variance estimates were low, resulting in heritability estimates of 0.013 for BW 0.027 for CFW and 0.012 for MFD. The estimated covariances between direct additive and maternal additive effects (or,)were positive for BW and negative for CFW and MFD. The proportion of ou, to the phenotypic variance was 4.07o, -3.l%a and -2.4Vo for BW, CFW and MFD, respectively. It is concluded that the maternal component can be ignored due to its relative small effect on these traits. Direkte en maternale variansie-komponente en oorerflikhede is deur DFREMl-prosedures beraam vir skoonvaggewig (SVG), liggaamsgewig (LG) en gemiddelde veseldikte (GVD) in die Grootfonteinse Merinostoet. Direkte oorerflikhede is beraam as 0.381 ,0.289 en 0.626 vir LG, SVG en GVD, respektiewelik. Die beramings van maternale additiewe variansre was laag met gevolglike oorerflikheidsberamings van 0.013 vir LG, 0.027 vir SVG en 0.012 vir GVD. Die beraamde kovariansies tussen direkte additiewe en maternale additiewe effekte (o,,) was positief vir LG en negatief vir SVG en GVD. Die bydrae van oam tot die fenotipiese variansie was 4.07o, -3.17o en -2.47o vir LG, SVG en GVD, respektiewelik. Daar word tot die gevolgtrekking gekom dat die maternale komponent weens die relatiewe klein effek op hierdie eienskappe, geignoreer kan word.