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Linear type traits in a Merino flock subjected to selection for increased clean fleece mass and an unselected Control Flock

S.W.P. Cloete

Elsenburg Agricultural Centre, Private Bag, Elsenburg,

7607 Republic of South Africa

J.J. Olivier

Karoo Region. Grootfontein Agricultural College. Middelburg,

5900 Republic of South Africa

Elizabeth du Toit

Tygerhoek Experimental Farm, P.O. Box 25,

Riviersonderend, 7250 Republic of South Africa 


Data from 267 individuals were used to investigate factors influencing 13 linear type traits (scored on a 1-50 point scale) in progeny of a Merino flock subjected to 20 years of selection for increased clean fleece mass (Selection Group, 116 individuals) and an unselected Control Group (151 individuals). Live mass (LM), clean yield, clean fleece mass (CFM), staple length, fibre diameter (FD) and total fold score (TFS) were recorded on the same animals. Average scores for type traits in Selection Group progeny were either similar to, or better (P ≤ 0.05) than those of their Control Group contemporaries in the cases of head: general, face colour score, staple formation as well as belly and points. The random effect of sires within groups was significant (P ≤ 0.05) for nine type traits, which suggests the possibility of generic variance for these traits. No major antagonistic phenotypic correlations of type traits with LM and CFM were found. Both FD and TFS had antagonistic correlations with staple formation score and belly and points score, while FD was also antagonistically correlated with scores for head: general. The only antagonistic phenotypic correlations amongst type traits were the negative relationships of scores for wool quality and evenness of crimp with scores for staple formation and belly and points. Phenotypic correlations were comparable with regard to sign and magnitude in the Selection and Control Groups.



South African Journal of Animal Science 1992, 22(2)