The impact of range use on caecal microbiota composition in free-range laying hens

Published: October 14, 2025

Source : I. RUHNKE 1, C. NORMANT 2, R.V. RAJ 3, J. SUCHODOLSKI 3, D.L.M. CAMPBELL 4, S.K. KHERAVII 1 and S-B. WU 1 / 1 School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia; 2 Institut Polytechnique LaSalle Beauvais, Beauvais, France; 3 Gastrointestinal Laboratory, Texas A&M University, College Station, Texas, USA; 4 F.D. McMaster Laboratory, Chiswick, Commonwealth Scientific and Industrial Research Organisation, Armidale, NSW, Australia.

The composition of gastrointestinal microbiota has been demonstrated to affect behaviour and vice versa (Neufeld et al., 2011; Berthoud, 2008). In free-range laying hens, the individual preference to range can lead to characteristic sub-populations of the flock (Hinch & Lee, 2011). The purpose of this study was to investigate the impact of ranging behaviour on caecal microbiota in laying hens.

A flock of sixty ISA Brown laying hens was housed in the UNE research facilities with daily range access from 21 weeks of age. Radio-frequency identification (RFID) tracking technology was employed to evaluate daily range usage of the individual hens. The experiment started when hens were 43 weeks of age. The RFID data of ranging behaviour across 39 consecutive days were used to select hens; Group 1 (n=10) spent the least while Group 2 (n=10) spent the most, time on the range (Table 1). Caecal content was collected from hens at 49 weeks of age, DNA extracted (Kheravii et al., 2017) and microbial profiling done at the Australian Genome Research Facility. Statistical analysis was performed using univariate non-parametric Mann-Whitney tests with adjustments for multiple comparisons using the Benjamini-Hochberg adjustments (significance set at P < 0.05).

Table 1 - Range usage of hens that were sampled for caecal microbiota characterisation (Mean±SEM).

At the phylum level, only Tenericutes differed significantly between the two groups (P=0.05), whereas no significant difference was observed for Actinobacteria, Bacteroidetes, Deferribacteres, Elusimicrobia Firmicutes, Fusobacteria, Lentisphaerae, Proteobacteria, Spirochaetes, Synergistetes and Verrucomicrobia. At the family level, significant differences were observed for unclassified RF39 (Mollicutes), Porphyromonadaceae and unclassified RF32 (Alphaproteobacteria) between the two groups (P < 0.05). In conclusion, the ranging activity of free-range laying hens at 49 weeks of age had a minor impact on caecal microbiota composition.

ACKNOWLEDGEMENTS: Research was financially supported by the Australian Poultry CRC.

Presented at the 29th Annual Australian Poultry Science Symposium 2018. For information on the latest and future editions, click here.