In Indonesia, the Javanese Fat Tailed Sheep is a very popular domestic anim
al for its meat production. However, selection to increase body weight has
never been done by local farmers. As a result the variability of body weigh
t is high, and expected that application of a selection program can improve
this trait Two steps of selection were done in order to improve birth and
body weight. In the first selection, the elite group was established by sel
ecting the best 40 females and 3 males from 12500 sheep reared by local far
mers based on their mature body weight and tail length. The control group w
as established by randomly selecting 40 females and 4 males. In the second
step of selection, the best 50% females and 5% males of the progeny of the
elite group was selected based on their weaning weight and tail size. The f
irst selection results indicate that there was a positive genetic progress
in both birth and weaning weight. Selection had increased 7.17% and 5.48% o
f male and female birth weight respectively and 9.48% and 9.78% of male and
female weaning weight, respectively. Positive genetic progresses of birth
and body weight were also found after the second selection. Birth weights o
f males and females were 6.75% and 7.20% higher than those in the control g
roup. Male and female weaning weights were 5.60% and 8.19% higher than thos
e in the control group, however, selection for weaning weight did not affec
t reproductive traits.