Impacts of Rearing Enrichments on Ranging in Free-Range Laying Hens

Free-range layer systems are increasing globally but range use can be low, particularly when birds are first provided outdoor access. It is recommended to match the rearing system with the layer system for optimal bird welfare (Janczak and Riber, 2015). However, within Australia, pullets destined for free-range systems are typically reared indoors which may hinder their adaptability to the outdoor environment as adults. Rearing enrichments may optimise behavioural development and better prepare hens for outdoor access. This study assessed whether different rearing environments up to 16 weeks of age would affect the initial range use of free-range hens.

Hy-Line Brown chicks (n = 1386) were reared in nine pens with three replicates of three treatments – control (standard litter), novelty (novel objects changed weekly), or structural (perching structures). At 16 weeks pullets were transferred to nine identical pens in an experimental free-range facility with standard floor litter housing, perches, nest boxes, but no additional enrichments. All birds were leg-banded with microchips and radio-frequency identification systems (RFID) were placed within each pen’s pop hole. Daily range access was provided from 25 weeks and time spent outdoors was tracked for 5 weeks. The RFID systems had double sensor sets to determine direction of hen travel (out to the range or back inside) and any unpaired (false) readings were filtered out before analysis. Data from the RFID systems provided the average daily time outdoors per individual hen. Video recordings of hens on the range were observed to count the number of hens on the range simultaneously at different distances from the shed across the length of the range area (1.2 to 5m, 5 to 10m, 10 to 20m, and 20 to 31m) every 30 minutes for the first 2 weeks of range access.

General linear models showed no significant differences between rearing treatment groups in the average daily time that individual hens spent outside during the first 2 weeks (P =  0.34) but more structural hens were on the range together simultaneously as shown by the counts of hens at specific time points from the video footage (P < 0.0001). The structural birds also spent more time outside during weeks 3-5 of range access than the other two treatment groups (mean daily hours ± SEM; structural: 1.71 ± 0.09, novelty: 1.38 ± 0.07, control: 1.40 ± 0.08) P < 0.0001). Thus, enrichments during rearing can modify adult hen behaviour and may provide management options for improving bird use of the outdoor range area during the initial access period. Perching structures during rearing may have improved the spatial navigation abilities of those hens (Norman et al., 2019). Further analyses of individual range use across the full flock cycle will show whether any initial differences persist or change with increasing hen age.

ACKNOWLEDGEMENTS: This research was supported by PoultryHub Australia.