The impact of early-life intervention on microbiota composition in free-range laying hens

Laying hens need to maintain their health status, including their gastrointestinal health until at least 72 weeks of age. Gut microbiota composition is extremely important to gastrointestinal and overall health. Furthermore, the gut-brain axis enables interactions between the enteric microbiota, the enteric nervous system and the central nervous system (Dinan & Cryan, 2017). The composition of gastrointestinal microbiota can be affected by animal behavior and vice versa (Neufeld et al., 2011; Berthoud, 2008). The purpose of this study was to investigate the impact of early-life intervention on caecal microbiota composition in laying hens.

A total of 300 day-old Hy-Line Brown layer chicks was obtained from a commercial hatchery and randomly allocated into two groups of 150 birds each. Birds in group 1 were reared under standard conditions according to the Hy-Line management guide. Birds in group 2 were reared using unpredictable environmental stimulations. The stimulants included visual and audio noise, toys and equipment, and was applied from 4-21 days of age. From 21 days onwards, hens in both groups were housed under exactly the same conditions. At 12 weeks of age, hens were moved to the same laying facilities and housed in two separate indoor pens with identical resources. All birds received commercial feed and litter from the same source and were maintained by the same personnel. At 21 weeks of age, 12 hens were randomly selected from each group and sacrificed. Caecal content was collected for microbiota analysis. The Australian Genome Research Facility performed microbial diversity profiling from the extracted caecal DNA. Statistical analysis included univariate non-parametric Mann-Whitney tests with adjustments for multiple comparisons using Benjamini-Hochberg adjustments (P < 0.05 was considered statistically significant).

At the phylum level, levels of Actinobacteria and Bacteroidetes were significantly higher in hens from group 2, compared to hens from group 1 (P = 0.05). At the order level, significant differences were observed for various groups, with levels of Clostridiales and Campylobacterales significantly higher in hens from group 1, which were reared under standard conditions. Further, differences various levels could be observed.

In conclusion, early-life intervention had a significant impact on caecal microbiota composition.

ACKNOWLEDGEMENTS: This research was financially supported by the Australian Poultry CRC.