Selection for increased weight of Awassi sheep in Iraq

Abstract

Expected genetic progress in Awassi sheep when selection was based on weaning or yearling weight alone was calculated using genetic parameters, phenotypic means and environmental adjustment constants derived from records of the Awassi flock maintained by the Agricultural Experiment Station of Mosul University, Iraq. Least-square were presented which may be used to remove average differences due to environmental effects such as age of dam, sex of lamb and year, month and type of birth. If selection was based on yearling weight alone, the expected genetic progress per generation would be approximately 5·7 times as great as that when selection was based on weaning weight alone. The greater expected progress is due to the higher estimate of heritability of yearling weight and the greater variation in this trait.