Effect of Methods to Control Egg Production on the Economical Profit in the Laying Hen

Abstract

The egg price in Japan has been showed a fluctuating curve like the low price occurred from April to August and the higher price from September to December. Therefore, as a way of improving economical profit, controlled egg production method was studied, which was intended to improve feed conversion ratio in the lower egg price period and egg production in the higher egg price period. The experiments were conducted Yamanashi, Shiga and Gifu prefectural poultry experimental station with 540 commercial layers. They were hatched April 1975 and reared until 48 weeks of age with the same management. Then they were divided into 3 groups of a control group and two experimental groups. The experimental period was 40 weeks, i. e., from 48 to 88 weeks of age. The control group was fed commercial layer's diet (CP 16%) ad libitum. One of experimental groups (Restrict group) was fed the diet restrictively at 90% of feed consumption of the control group from 48 to 68 weeks of age and thereafter fed ad libitum. Another experimental group (Restrict & fast group) was also fed the diet restrictively as those of Restrict group from 48 to 64 weeks of age, afterwards was fasted for 3 weeks, which resulted in forced molting, and then refed the diet ad libitum from 68 to 88 weeks of age. The economical profit was estimated with the formula, raw profit per day per bird=(egg price×egg production weight per day per bird)-(60 Yen per kg×Feed consumption per day per bird). The egg price was used fluctuating egg price which was calculated with the data of 1973-1977.1. In restricted feeding period, the Restrict group was 1.6% lowerr than the control group in egg production rate, but was superior 0.11 in feed conversion ratio and 0.2 Yen per day per bird in raw profit to the control group. However, after the group was returned to ad libitum feeding, compensatory egg production did not be observed in the group, when compared the economical profit in the total period, the Restrict group was similar with the control group.2. In restricted feeding period, the performance of the Restrict & fast group was similar as those of the Restrict group. After fasting period, the peak of egg production rate of the Restrict & fast group was raised up to 80.3% and this time was coincided with the higher egg price period. Therfore the raw profit per day per bird of the Restrict & fast group was 1.34 Yen higher than the control group from 68 to 88 weeks of age. As a result, in total experimental period, the Restrict & fast group was 2.3% lower in egg production rate than the control group, but was superior 0.13 in feed conversion ratio and 0.4 Yen per day per bird in raw profit to the control group.3. Egg shell quality was not influenced by restricted feeding, but was improved siginificantly by forced molting.