Effects of beak trimming and cage design on laying hen performance and egg quality.

1. Conventional cages are to be replaced by furnished cages or aviary systems to improve the welfare of hens. We compared the performance and egg quality of hens reared in two designs of furnished cages and of two standard cages. We also explored the consequences of the absence of beak trimming when using these designs. 2. Hens (2028) were housed from 18 to 70 weeks of age in 108 standard cages at 6 per cage (60 cmx63.5 cm), in 96 cages at 5 per cage (59.5 cmx55.5 cm) or in two designs of furnished cage at 15 per cage (24 F15M cages and 36 F15P cages made by two manufacturers) which contained equipment varying in size and location (nests, dust baths and perches). Half of the hens were beak-trimmed in each design. 3. Mortality was low in beak-trimmed hens (<5%) but was unacceptably high in non-beak-trimmed hens due to cannibalism (>40%, 516 hens). Mortality was worse in standard cages than in furnished cages. Consequently, hen-housed egg production was significantly lowered in non-beak-trimmed hens. 4. Egg laying in beak-trimmed hens reared in furnished cages occurred mainly in the nest (80 and 84.8% in F15M and F15P) but also in the dust bath (13.3 and 9.4% in F15M and F15P) and in other parts of the cage (6.7 and 5.8% in F15M and F15P). 5. The total percentage of broken (visual observation) and hair-cracked eggs (candling) was high in the furnished cage designs (15.4 and 19.6% in F15M and F15P, respectively) compared with standard cage designs (8.1 and 12.2% in S6 and S5). This was mainly due to hair-cracked eggs, the highest percentages occurring in the nests, especially in the design with a narrow nest and no egg saver (11.1% in F15M compared to 17.6% in F15P) as a consequence of egg accumulation in the cradle and relatively low frequency of manual egg collection. 6. Eggshell quality (index and breaking strength) was only slightly influenced by cage effects so differences in egg breakage were attributable to impacts related to cage design. 7. It is concluded that beak trimming remains the most effective way to prevent cannibalism, although furnished cages with a large group of hens slightly reduced the incidence, and that further development and optimisation of furnished cages is needed to reach egg quality similar to standard cages.

Comparison of eggshell hygiene in two housing systems: standard and furnished cages.

1. The hygienic properties of eggs produced in two designs of furnished cage were investigated and compared to two standard cage designs. 2. At 28, 37, 47 and 58 weeks of age, the proportion of dirty eggs was higher in one of the furnished cage designs while, in the other, it was similar to standard cages. 3. At 27, 33 and 60 weeks, the bacterial load on the eggshell (total aerobic bacteria and enterococci) was higher in furnished cage designs. A seasonal effect was observed with lower counts at 60 weeks (winter) than at 27 weeks (summer). 4. More dirty eggs and a higher bacterial load were observed in eggs laid outside the nests, which suggests egg hygiene in furnished cages could be similar to standard cages if the equipment in furnished cages was improved to enhance nest laying.

Changes in eggshell mechanical properties, crystallographic texture and in matrix proteins induced by moult in hens.

The effect of moult on eggshell mechanical properties, on composition and concentrations of organic matrix components and on eggshell microstructure was investigated. The observed changes were studied to understand the role of organic matrix and eggshell microstructure in eggshell strength. Moult was induced by zinc oxide (20 g zinc/kg diet) in 53 ISA Brown laying hens at 78 weeks of age. No difference was observed for egg or eggshell weights after moult. In contrast, moult improved the shell breaking strength (28.09 vs 33.71 N). After moult, there was a decrease in the average size of calcite crystals composing the eggshell and in their heterogeneity, whereas crystal orientation remained basically the same. After moulting, the total protein concentration in eggshell increased slightly. The comparisons of SDS-PAGE profiles of the organic matrix constituents extracted before and after moulting showed changes in staining intensity of certain bands. After moult, bands associated with main proteins specific to eggshell formation (OC-116 and OC-17) showed higher staining intensity, while the intensity of the egg white proteins (ovotransferrin, ovalbumin and lysozyme) decreased. ELISA confirmed the decrease in ovotransferrin after moult. Its concentration was inversely correlated with breaking strength before moult. These observations suggest that changes in eggshell crystal size could be due to changes in organic matrix composition. These changes may provide a mechanism for the improvement in shell solidity after moulting.