Abstract
Data on birth weight records of 450 Rambouillet lambs sired by
16 rams of the same breed, recorded from 1978 to 1985 were used to
calculate heritability, Average birth weights were 3.49 + 0.05,
3.26 + 0.05 and 3.38 + 0.04 kg for male, female separately and
for both combined. There was significani difference in birth wei-
ghts between years and sexes, Heritability was calculated by 5
different methods, namely paternal halfsib correlation, intrasire
regression of offspring on dams, regression of offspring on mid
parents. regression of offspring on dam and regression of offspring
on sire, The calculated heritabiltty values were 0.034 + 0.162,
0.0194 + 0.104, 0.617 + 0.060, 0.040 + 6.10 and 0.050 4+ 0.070,
Repeatability of birth weight was 0.03355 + 0.915. Paternal halfsib
correlation yielded higher value of heritability than other methods.
Low value of heritability indicated that birth weight of lambs was
significantly affected by environment than by genetic factors.
