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The influence of non-genetic factors on selection policy for fibre diameter

J.J. Olivier, G.J. Delport1, G.J. Erasmus1 & A.O. de Lange2

Karoo Region

1 Fleece Testing Centre

2 U O F S 


The effect of variation in non-genetic factors on the accuracy of subjective selection for fibre diameter in the Grootfontein Merino stud was investigated.

Mixed model methodology was used to separate genetic and environmental trends in fibre diameter. BLUP for parents and BLUP for non-parents were obtained using a "Reduced Animal Model". Selection pressure for fibre diameter coincided with the trend in non-genetic factors leading to selection of animals with a genetic potential for thicker fibres during times of adverse environmental conditions.

Subjective selection of fibre diameter was influenced by non-genetic factors leading to virtually no selection in poorer environments.  



SASAP Congress 1988