Production and egg quality in brown hens kept in a cage-free system: effect of hen age and nest lighting

The study evaluated the effects of hen age and nest lighting on egg production and quality, and oviposition pattern from 26 to 45 weeks of age in 1800 Lohmann Brown-Classic hens housed in 8 pens of an aviary system. From 17 to 26 weeks of age, half pens had the nest opened with the inner led light turned on 1.5 h before turning on the installation light (5:30); the other half had the nests closed until turning on the installation light and without any inner led light. Measurements were taken weekly and monthly. As hen age increased, the oviposition rate (p < .001) increased from 89.1% housed hens (on average of 26–34 weeks) to 92.8% (34–45 weeks). Both the oviposition rate of broken and dirty eggs decreased from the first period (5.13% and 7.65% on average, respectively) to the second period (2.28% and 4.21%) (p < .001). The weight and width of the eggs increased and the shape index decreased as age increased (p < .001). As for oviposition pattern from 26 to 45 weeks, eggs laid in the first hours (5:30–7:30) decreased (76.4–45.8% of eggs laid in 24 h), whereas eggs laid in the rest of the day increased (p < .001). Moreover, eggs laid in the nest (as % eggs laid in each time interval) between 5:30 and 7:30 (77.9–86.4%) and between 7:30 and 9:30 (68.3–84.7%) increased from 26 to 45 weeks (p < .001). A significant decrease of broken eggs (% eggs laid in each time interval) was also recorded for the eggs laid within 9:30 when the hen age increased. The use of nest lighting from 17 to 26 weeks increased oviposition rate in the following period (26–45 weeks) from 90.1% to 92.3% (p < .001), decreased egg weight, width, and surface (p < .001) as well as the rate of broken (4.22–3.43%; p < .001) and dirty eggs (5.98–5.65%; p = .10), whereas the rate of defective eggs was not affected. The oviposition pattern (i.e. distribution of eggs laid in the different daily time intervals) did not change. In the first time interval (5:50–7:30), eggs laid in the nest were higher (83.2% vs. 80.2% eggs laid in the time interval; p < .01) and broken eggs lower (4.83% vs. 7.01%; p < .01) in the case of the presence of nest lighting. Based on the above results, changes in the oviposition during the day according to hen age must be considered in cage-free systems to assure a correct use of nests. As for early nest lighting, further investigation is worth in view of the positive effects on egg production and quality, and on nest use