The overall hen-day egg production was not significantly
different between the 2 cage designs. The
only significant difference between treatments was
observed in period 10, in which birds in conventional
cages (CON; 88.6%) had higher (P < 0.05) hen-day
egg production than birds in the enriched cages (ENR;
87.0%). The rate of lay in both treatments, over the period
of 21 to 61 wk, ranged from 84.5 to 95.9% and was
within the commercial production standards for Shaver
White hens (Table 1). Shaver White hens on average
achieve production rates of 84.7% at 60 wk and 96.0%
at peak (Institut de Selection Animale B. V., 2007).
Peak production occurred in period 4, between wk 34
and 37, and egg production then gradually declined.
Caging type did not affect the overall feed consumption
of laying hens. However, birds in conventional cages
consumed significantly more feed than birds in enriched
cages in periods 1 and 4 but significantly less in period
8 and 9 (Table 2). There was a significant (P < 0.0001)
period effect for feed consumption. Feed consumption
was highest in period 5, remained relatively constant
throughout periods 6 to 8, and gradually declined from
period 9 to 10. Significant cage × period interactions
can be explained by a higher rise in feed intake in period
4 and more rapid decline in period 8 in conventional
cages. A significant effect of cage type on feed
efficiency was observed only in period 9 (CON = 1.97;
ENR = 2.01). However, there was a significant (P <
0.0001) period effect on feed efficiency. Feed efficiency
significantly improved in period 3 and 4, increased from
period 5 to 7, remained relatively constant from period
8 to 9, and increased again in period 10 (Table 1). Although
the cumulative percentage mortality (for the
full 40 wk) was numerically lower in conventional cages
(4.0%) than in enriched cages (5.6%), cumulative percentage
mortality between cages was not statistically
significant. Mortality for both cages remained relatively
constant from period 1 to 3 (CON = 0.2 to 0.4%; ENR
= 0 to 0.2%) but steadily increased from period 4 to 10
(CON = 0.6 to 4.0%; ENR = 0.8 to 5.6%).
Average egg weight did not differ between the 2 cage
types. The weights of eggs of birds in conventional cages
were higher in period 2, 4, and 6 but these did not
affect the average. As expected, egg weight increased
with hen maturity. A significant (P < 0.0001) increase
in egg weight throughout the duration of the production
cycle was observed. Egg weight increased substantially
from period 1 to 3, followed by a gradual but
steady increase from period 4 to 10 (Table 1). A cage
× period interaction (P < 0.01) was evident as a result
of heavier eggs being produced by hens in conventional
cages than in enriched cages, with progressive maturity
(periods 2, 4, and 6). Consistent throughout the
production period, the specific gravity of the eggs was
similar between cage types (Table 2). Specific gravity of
eggs from both cages gradually declined (P < 0.0001)
from period 1 (1.0887) to period 10 (1.0829). Cage type
did not affect the overall percentage of cracked eggs
(Table 2). Apart from a higher percentage of cracked
eggs of birds in conventional cages in period 7 and 8