APSS 2013 Proceedings - The University of Sydney

Aust. Poult. Sci. Symp. 2013.....24
between BT and EE. Pullets in the non-trimmed/non-enriched treatment were recorded to lay
fewer eggs in early lay and hence were perhaps less mature than birds in the other treatment
combinations. Nevertheless, the eggs produced in weeks 19-20 were below saleable size and
hence had no commercial value. It is not evident however, which component(s) of
enrichment might have contributed to modify the early development of egg laying. Although
there were no effects of enrichment on hen weight in the experiment, there was a strong
effect of BT on weight. This effect may be due to genetic differences rather than treatment.
The high incidence of floor eggs in the present experiment is a concern as it may be
difficult to induce hens to lay in nest boxes if the birds are initially attracted to lay on the
floor. Cronin et al. (2007) reported that the majority young hens studied in furnished cages
were consistent in their choice of egg-laying site by about the tenth egg laid, which suggests
it is important to focus on managing the pullets’ environment to encourage birds to lay in the
nest boxes rather than on the floor. One factor that influences hens in the selection of egglaying
site is ambient light, with hens typically seeking darkened sites for egg laying. Further,
Cronin et al. (2012) suggest hens may also seek egg-laying sites where they are less likely to
be disturbed by other hens. An interesting finding in the present experiment was that once the
pop holes were opened, the proportion of floor eggs laid in the rear half of the pens
decreased, suggesting at least some hens relocated their egg laying site. While some hens
continued to lay floor eggs, albeit in the front half of the pen, other hens seem to have chosen
to lay in the lower level nest boxes. This shift in egg laying location towards the pen front,
including the lower nest boxes, may have been influenced by increased light entering the rear
of the pens via the pop holes, and/or disturbance near the pop holes at the rear of the pens.
In conclusion, the results of the experiment demonstrate that factors applied during
rearing to modify FP behaviour may also affect egg laying characteristics, although the latter
effects may be relatively transient.
ACKNOWLEDGEMENTS: Kate Hartcher is the recipient of a Poultry CRC scholarship. The
experiment was funded by AECL and we gratefully acknowledge Assoc. Prof. Peter
Thomson for the statistical analysis and Mary Anne Cronin for her assistance with care of the
birds and collection of eggs.
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