|Abstract or Summary
- A series of 8 experiments was conducted to investigate various
methods of delaying the sexual maturity of developing White Leghorn
(W. L.) pullets grown during a period of increasing day length and to
control the feed intake of W. L. layers. In the first five experiments
W. L. pullets were fed low-lysine (0.54%) and low-protein (10.36%)
developer rations from 8 to 20, and 8 to 20 or 12 to 20 weeks of age,
respectively. Other groups were subjected to watering regimes in
which water was cycling on 24 hr.--off 24 hr. and on 24 hr.--off 48 hr.
from 8 to 20, and 8 to 20, 12 to 20, or 14 to 20 weeks of age,
respectively. Additional groups were reared using two lighting programs;
the first featured a gradual decline of 15 min./week in the
day length from 0 to 22 weeks of age. The second provided a constant
amount of light from 0 to 12 weeks of age, a sudden 5-hr. drop at
12 weeks, and then a constant level from 12 to 20 weeks of age. In
Exp. 6 to 8, W. L. layers were provided water concurrent with light (15.0--16.25 hr./day), 15 min. each hour, three or five 15-min.
periods/day or two 2-hr. periods per day. An additional group had
access to feed for two 2-hr. periods per day.
The low-lysine developer had no effect on body weights, sexual
maturity, or feed intake during the growing period. These pullets
tended to lay fewer, but heavier, eggs during 40 weeks of lay. Cannibalism
tended to be higher in the pullets fed low lysine. Feeding the
low-protein developer from 8 or 12 to 20 weeks of age resulted in significantly
lower body weights and feed consumption in the developing
period. Fed from 8 to 20 weeks of age, this diet led to 14 and 11-day
delays in reaching 25 and 50% production, respectively. Lay house
performance was satisfactory in three of four comparisons, but brooder
house mortality was slightly higher in pullets fed the low-protein
Providing water every other day after 8 weeks of age did not
significantly alter feed intake, body weights, or sexual maturity.
Feed intake in the subsequent lay period was significantly lower for
dwarf W. L. pullets, but unaffected in normal W. L. pullets. Hen-day
production tended to be slightly lower and lay house mortality slightly
higher for these pullets. Providing water every third day from 8,
12, or 14 to 20 weeks of age significantly reduced body weights and
feed intake, and delayed 25 and 50% production. The degree of growth
retardation was proportional to the duration of the water restriction
regime. These pullets tended to lay at a higher rate, require less
feed per egg, and lay larger eggs.
Pullets subjected to either of the lighting programs ate more and
were heavier in the first 12 weeks of life, but consumed less from 12 to 20 weeks and weighed less than the control group at 20 weeks of
age. Both lighting programs increased average egg weights in the laying
period. A 5-hr. light reduction at 12 weeks of age delayed 25 and
50% production as much as 11 and 14 days, respectively. There were no
significant differences in egg production, feed per hen-day, per egg,
or per gram of egg.
Providing hens two 2-hr. or three 15-min. waterings after 5
months of lay significantly reduced egg production, reduced feed intake
and weight gain, but had no effect on average egg weights. When
the three 15-minute regime was initiated prior to lay, egg production
was not altered, but feed per hen-day, per egg and per gram of egg,
and average egg weight were reduced by 3.0, 11.0, 0.1, and 2.6 g.,
respectively. The number of large eggs was significantly reduced.
Egg production tended to be higher when pullets were provided
five 15-min. waterings each day. No adverse effects were observed on
average egg weights or mortality. In two comparisons, feed per henday,
per egg, and per gram of egg were reduced by 0.3 and 3.0, 7.7 and
9.0, and 0.14 and 0.17 g., respectively. Providing layers water 15
min. each hour had no effect on egg production, feed intake, or weight
gain during lay. In one comparison egg size was significantly increased
and the number of medium eggs significantly reduced. These hens
required slightly less feed to produce a gram of egg.
Providing laying hens two 2-hr. feedings significantly reduced
egg production and weight gain during lay, reduced egg mass per henday,
increased mortality, but had no effect on average egg weights.
Feed per hen-day was decreased by 4.7 g., but feed per egg and per
gram of egg were increased by 3.9 and 0.07 g., respectively.