Die doeltreffendheid van vroeë seleksie van Merinoramme op grond van ‘n seleksie-indeks (Kort mededeling)

Author: D.G. Poggenpoel
Year: 1991
Issue: 1
Volume: 21
Page: 55 - 58

Efficiency or early selection or Merino rams on a selection index. Production traits of 196 unselected young Merino rams were measured at two consecutive shearings with six months’ wool growth, at the age of 12 and 18 months. The correlation between repeated measurements of the same traits was about 0,60. Final selection was based on a selection index estimated from measurements of body mass, clean wool mass and fibre diameter over a 12-month period with relative weighing factors of 1: 25: -9 respectively. A similar selection index, based on the first six months’ data, had a correlation of 0,84 with the final total selection index. Consequently, early selection based on an early selection index would be highly efficient. With 50% selected at the early stage and 5 – 20% at the final stage, the efficiency of selection would still be close to 100%. A simple selection index based on body mass and greasy wool mass with relative weighing factors of 1: 15 (including no data of fleece analyses) had a correlation of 0,45 with the final selection index. If 50% would be selected at the early stage according to this index, the efficiency of selection would decrease by about 5%. The results obtained were in agreement with the theory of early selection.



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