SOME PRENATAL EFFECTS ON BIRTH SIZE IN LINCOLN AND SOUTHDOWN LAMBS PRODUCED BY RECIPROCAL OVUM TRANSFERS

Abstract

Effects at birth due to maternal environment, breed of lamb, litter size and sex of lamb on body weight and cannon bone length and width were studied in lambs born naturally and as a result of reciprocal ova transfer between Lincoln and Southdown ewes. Maternal environment, breed of lamb and litter size had a significant effect (P < 0.01) of 0.63, 0.59 and 0.61 kg, respectively, on birth weight. Effects due to sex of lamb on birth weight were small and not significant. Southdown lambs carried by Lincoln dams were 0.80 kg (25%) heavier at birth than those carried in their natural environment, but Lincoln lambs carried by Lincoln dams were only 0.50 kg (10%) heavier at birth than those carried by Southdown dams. Breed of lamb had a highly significant effect (P < 0.001) on cannon bone length, but effects due to all other factors were small and not significant. On cannon bone width only the effect of litter size was significant (P < 0.05).