- Ewe productivity (2) - effectiveness as a selection criterion.
|Last update: August 18, 2011 02:25:32 PM|
Ewe productivity (2) - effectiveness as a selection criterion.
G J Delport, A 0 De Lange1, G J Erasmus2 and J J Olivier3.
S A Fleece Testing Centre, ADSRI, Middelburg, Cape.
Applying ewe productivity to Merino ewes in the Klerefontein selection experiment resulted in breeding values for four different traits as described in presentation (1 ) . Pearson's product moment correlations were used to determine the effectiveness of the ewe productivity criterion when making use of different amounts of information. Selection of ewes on the basis of their dam's ewe productivity can be practised with an accuracy of 0,513. The accuracy of the selection of rams also on their dams performance is only 0,069. The correlation between the breeding values of sires and the average breeding values for ewe productivity of their ewe progeny is equally low (0,043). Although preliminary selection of ewes on their dams performance therefore seems feasible, selection of males on basis of information on female relatives currently is not a viable proposition. In terms of lifetime reproductive efficiency the best 10% ewes on ewe productivity produced 42% percent more lambs than the poorest 10% ewes. The correlation between ewe productivity and 18 months body was 0,301. No serious adverse correlations with 18 months wool traits could be found. It is therefore concluded that ewe productivity can be used in a highly effective way to improve reproductivity of the ewe flock without simultaneous adverse changes in wool traits.
(1) ARDRI, University of Fort Hare, Alice, Ciskei.
(2) University of the OFS., Bloemfontein.
(3) Karoo Region, Middelburg, Cape.
Proceedings 28th SASAP congress