Abstract
Two experiments were carried out to investigate the effect of the time of oviposition on egg quality characteristics in two different housing systems (cages vs. litter). ISA brown hens from 20 to 64 weeks of age were housed in battery cages (550 cm2/hen, 19 526 laying hens in the house) and on deep litter (7 hen/m2, 4 652 laying hens in the house). In both houses, eggs were collected daily at three oviposition times 06:00, 10:00 and 14:00 h. Every four weeks, 90 eggs for each house (30 eggs for each oviposition time) were used for egg quality assessment. The results indicated that in cages the highest percentages (P ≤ 0.001) of normal (74.47%), non-standard (0.85%) and cracked (1.80%) eggs were laid in the early morning (06:00 h). On deep litter, however, the highest percentages (P ≤ 0.05) of normal sound eggs were produced at10:00 h (35.43%) and at14:00 h (33.03%). In the cage system, the heaviest eggs (63.01 g) were laid in the early morning (06:00 h) and the highest shell percentage (10.33%) was in eggs laid in the afternoon and also at 10:00 h (10.31%). On the other hand, in the litter housing system, the time of oviposition had no significant effect on egg weight and eggshell quality characteristics except for shell thickness. Morning eggs had greater shell thickness (0.398 mm) than afternoon eggs (0.390 mm). In cages and on litter, statistically significant differences in albumen height, albumen index and Haugh Units were observed between early morning eggs and afternoon eggs and data showed a pattern of relatively higher albumen quality for eggs collected in the afternoon in both systems.