Abstract
Three experiments were conducted to study the effect of feed restriction during the rearing period alone or both rearing and laying periods upon subsequent performance in meat-type breeder pullets.
Experiment 1 was conducted using 338 birds of the six different breeds, each hatched in March. The control group of each breed was full-fed during the whole experimental period from the day of the start of feeding ("O" day of age) to 518 days of age. The restricted feeding group was subjected to a skip-a-day feeding (9 hours fed per 48 hours) from 71 to 154 days of age and thereafter full-feeding until the termination of experiment.
Experiment 2 was conducted using 233 birds of the four breeds, each hatched in July. The control groups were full-fed during the whole experimental period: 0-357 days of age. The restricted feeding groups were fasted for 6 days from the day at which the birds of 10 or more percent of the group had started to lay eggs.
Experiment 3 was conducted with the following four different feeding programs using 72 birds of one breed, hatched in March: (F-F) full-feeding during the whole experimental period (0-518 days of age), (F-R) full-feeding during the rearing period (0-154 days of age) and restricted feeding to 90% of (F-F) group during the laying period, (R-F) skip-a-day feeding from 71 to 154 days of age and then full-feeding until the termination of experiment, and (R-R) skip-a-day feeding for the same period as in (R-F) group, full-feeding from 155 to 182 days of age, and then restricted feeding to 90% of (R-F) group until the termination of experiment.
In Experiment 1, in which a skip-a-day feeding program was adapted, the age at sexual maturity in the restricted feeding groups was almost uniform (178-183 days) throughout the six breeds and delayed 23.1 days in the average from that of the control groups in which it varied from 149 to 169 days. In the restricted feeding groups of four breeds, the hen-day egg production increased, while it decreased in the other two breeds. In an average of the six restricted feeding groups, a 2.0% increase was observed in the hen-day egg production. The increase in the percentage of settable eggs was 7.0% in the average of the six breeds, and increase in the egg weight was 1.7g in the average.
In Experiment 2, in which a 6-day-fasting was adapted, the age at first egg after the fasting treatment delayed 11.2 days in the average. The increase in the percentage of settable eggs was 7.5% in the average during the period of 191-280 days of age.
In Experiment 3, the delay in the age first egg in (R-F) and (R-R) groups, in which a skip-a-day feeding program was adapted in the rearing period, was 23.4 days in the average. A 5.1% increase in the percentage of settable eggs and a 1.6g increase in the average egg weight were found in these groups. In (F-R) and (R-R) groups, in which the feed restriction was adapted in the laying period, feed consumption was approximately 15% less than that in (F-F) and (R-F) groups, in which the feed restriction was not adapted in the laying period. Feed conversion ratio in (F-R) and (R-R) groups, which was 3.54 in the average, was less than that (4.05 in the average) in (F-F) and (R-F) groups, whereas the body weight was reduced. Feed consumption per settable egg was 307g (F-F), 275g (F-R), 298g (R-F), and 261g (R-R), respectively. the results indicate that the feed restriction throughout the rearing and laying periods improves the economic performance of meat-type breeder pullets.
