Adjustment factors for growth traits of Chios sheep

Abstract

Data on 3741 purebred Chios lambs, collected at Athalassa and Orites, were used to determine the effects of year, month and type of birth, sex of lamb and dam lactation number on pre-weaning and post-weaning growth traits of sheep. Least-squares analyses revealed that most of the factors studied had a significant effect ( P < 0.01) on lamb live weights. Flock effects were important for weaning weight only, but year and month of birth were significant for all live weights ( P < 0.01). Dam lactation number effects were small and insignificant for post-weaning growth rate alone. Although year-by-month interactions were in all cases significant, no changes in rank were detected. Type of birth-by-sex interaction was not significant for any of the traits studied. Adjustment factors were computed across year of birth for the effects of month of birth, type of birth, sex of lamb and dam lactation number. Since flock effects were insignificant, these multiplicative adjustment factors could be used in performance testing programs for the improvement of growth traits in Chios sheep.