Guesdon, 2004a – Laying performance and egg quality in hens kept in standard or furnished cages

A total of 1992 ISA Brown hens were housed from 18 to 70 weeks of age, in four different types of cages: 2 models of standard cages (S5 and S6) and 2 models of furnished cages (F7 and F15). These cages housed 5, 6, 7 and 15 hens respectively with areas per hen of 660, 635, 826 and 1134 cm². Furnished cages were fitted with a nest, a dust-bath and perches. The mortality rate was higher in the standard cages than in the furnished cages (cumulative mortality: S6 = 21%, S5 = 17%, F15 = 11%, F7 = 10%; P < 0.001). Mortality was mostly due to thermal stress and the difference between the 2 types of cages was probably attributable to the larger available floor space in the furnished cages, facilitating heat dissipation. The type of cage did not affect the laying rate. In the furnished cages, the percentage of eggs laid in the nest was low, especially in F15 (43.5% versus 68.1% in F7). The percentage of broken eggs was significantly higher in the furnished than in the standard cages (S5 = 5.4%, S6 = 3.3%, F7 = 7.7%, F15 = 8.4%). The difference between these two rearing systems was, however, considerably reduced when only the eggs laid in the nest were considered in the furnished cages (F7 = 4.9% and F15 = 5.1%). The percentage of dirty eggs was significantly different between the types of cages (S5 = 7.7%, S6 = 9.2%, F7 = 10.3% and F15 = 8.2%; P = 0.002). However, in the furnished cages, the number of dirty eggs was reduced when only the eggs laid in the nest were taken into account (F7 = 8.2% and F15 = 6.7%). We conclude that egg production could be similar in furnished and standard cages if most of the eggs were laid in the nest in furnished cages. This suggests that the improvement of furnished cages should first focus on the provision of more attractive nests.