PERFORMANCE AND EGG QUALITY OF LAYING HENS IN AN AVIARY SYSTEM

Laying hens were kept in an aviary system on a practical scale under S wedish conditions during five entire production cycles. All hens were non break-trimmed, since this is prohibited in Sweden. The aviary type used, Marielund, is a three-tiered aviary with litter. About 4700 hen s kept in four pens were housed in each batch. Lohmann Selected Leghor n (LSL) layers were used in all five trials. In addition to LSL, the L ohmann Brown (LB) was used in Trial 3 and an experimental cross (SLU-1 329) was used in Trial 5. The performance of the hens from 20 until 80 wk (18.6 to 22.5 kg/hen housed), as well as mortality (4.0 to 20.9%), varied between years. This variation was greater than could be expect ed in cage systems and was possibly the result of unpredictable cases of cannibalism, in the medium heavy brown hybrid especially, and/or pa rasitic disorders like Red mites or coccidiosis. The proportion of mis placed eggs (flow eggs) seemed to be influenced by rearing, but was al so observed to vary between different pens within batch. The total ran ge during the five trials was between 0.7 and 18.4%. The proportion of dirty eggs was highly dependent on the proportion of misplaced eggs.