The present study was conducted to study the effects of both breed and
" different systems of feed restriction during the rearing period from 10 up to 22 weeks
of age on growth and laying performance of Campbell and Domyati ducks. At 10
weeks of age, 180 ducklings (144 females and 36 males) from each breed were
randomly assigned to 6 feeding systems up to 22 weeks of age; where the first group
(control) was fed ad libitum throughout the experimental period (AL), the second and
third groups were fed on 80 and 60% of the intake of AL group (80 and 60% AL), the
4th group was fed 80% AL mixed with 20% fine sawdust (DL) and the 5th and 6th
groups were fed ad libitum daily except that feeding was skipped for one or two days
per week 0N1 and W2), respectively. During the laying period from 22 to 46 weeks of
age, however, all groups were fed on ad libitum basis.
The criteria of response were live body weight, flock uniformity, age at sexual
maturity, feed intake, feed conversion, laying rate, egg weight, egg mass, viability
percentage, eggs fertility and hatchability percentage, egg quality (shape index, shell
thickness and yolk index), and some blood constituents (plasma calcium, inorganic
phosphorus and progesterone), and costs, returns and economic efficiency. The
obtained results can be summarized as follows: Significant breed differences were
observed between the two breeds in live body weight at 22 weeks of age, flock
uniformity, age at sexual maturity, daily feed intake, egg weight, egg mass, level of
plasma progesterone (except at 30 weeks of age) and viability. However, feed
conversion, laying rate, eggs fertility and hatchability percentages, egg quality and
levels of plasma calcium and inorganic phosphorus were not affected by breed. The
application of feed restriction during the growing period (10-22 weeks of age) reduced
_ body weight at 22 weeks of age, delayed age at sexual maturity, and improved eggs
fertility and hatchability percentages. Feed restriction also significantly affected flock
uniformity, laying rate (in favour of DL and W2 groups), egg mass (in favour of 60%
AL, DL and W2 groups), viability, egg quality and blood constituents, while daily feed
intake, feed conversion and egg weight were not affected by feed restriction. Due to
the application of feed restriction during the growing period (10-22 weeks of age) the
feeding costs )'Jere decreased, and generally, this resulted in achieving greater results
and economic efficiency; especially with the 60% AL and W1 groups.