Published online by Cambridge University Press: 06 May 2016
The number of breeding sheep in a flock and the number of generations under selection will directly affect the genetic improvement possible. Both in cattle (Donald and El Itriby, 1945, 1946) and in pigs (Donald and Auerbach, 1942) a small average herd size and short life were found to have set severe limits to the breeding policies possible. The present report discusses this problem in lowland registered sheep flocks.