In our study we expressed the results of cholesterol
concentration as yolk cholesterol concentration
and egg cholesterol concentration. A significant
effect of housing systems on the yolk cholesterol
concentration (mg/g yolk) was observed each week
(except at 59 week of age, the differences between
the groups were not significant). The average yolk
cholesterol concentration (mg/g yolk) was the lowest
in enriched cages (12.5 mg/g yolk). The highest
yolk cholesterol concentration was noted in the
eggs from the litter system (14.1 mg/g yolk). The
eggs from conventional cages had the average yolk
cholesterol concentration of 13.3 mg/g yolk and the
eggs from the outdoor system contained 13.4 mg/g
yolk. The yolk cholesterol concentration in the
eggs from the outdoor system might be influenced
by forage intake. Our result is in agreement with
Basmacioglu and Ergul (2005), who proved that
the housing system had a significant effect on the
cholesterol concentration. Premavalli et al. (2005)
showed that the eggs laid by the birds in the elevated
cage system had significantly (P ≤ 0.01) lower yolk
cholesterol (11.29 mg) than those from the deep
litter system (11.58 mg). Similarly, Sauveur (1991)
observed a significant increase in the egg cholesterol
from the hens housed in alternative housing
systems. Tůmová and Ebeid (2005) examined the
effects of the time of oviposition on yolk cholesterol
in the cage system and litter system. No significant
differences were detected between the eggs laid in
the morning and those laid in the afternoon. These
authors also reported only a small difference between
the effects of different housing systems on
the yolk cholesterol concentration. Cerolini et al.
(2005) studied the cholesterol concentration in the
eggs from hens in four housing systems: organic,
with outside pen, floor system and battery cages.
The average content of cholesterol was 370 mg/100 g
edible egg and no significant changes were observed
between the groups, unlike our results.