Volume 161, December 2014, Pages 75–85
Use of dynamic and rewarding environmental enrichment to alleviate feather pecking in non-cage laying hens
Highlights
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- The impact of environmental enrichment on non-cage laying hen behavior was examined.
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- Hens were exposed to a plastic box (BOX), a hay bale (HAY), or nothing (CON).
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- HAY hens performed fewer gentle feather pecks (GFP) than BOX or CON.
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- HAY hens were more fearful during a manual restraint test.
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- HAY may be an effective strategy for alleviating GFP in adult non-cage laying hens.
Abstract
Feather
pecking (FP) can cause feather loss, resulting in physical injuries,
which may lead to cannibalism. FP appears to be a redirection of
foraging behavior, which intensifies when hens have difficulty coping
with stress and fear. Dynamic environmental enrichment (EE) may allow
expression of natural foraging behavior thus reducing conspecific
pecking behavior and alleviating hen injury. Three treatments (plastic
box: BOX; hay bale: HAY; and no enrichment: CON) were randomly applied
to 30 identical floor pens (10 hens/pen; 10 pens/trt). At the pen level,
hen behavior, and the number of severe FP (SFP), gentle FP (GFP),
aggressive pecks (AP), and enrichment pecks (EP) were recorded from
video prior to (21 wk) and after (24 wk) treatment implementation, and
when hens were 27, 32, and 37 wk of age. A manual restraint test (MR)
was performed immediately after behavioral observations and levels of
blood serotonin (5-HT) and glucocorticoids (GC) measured. Short-term
(ST) and long-term (LT) analyses identified the impact of EE over the ST
(21 vs. 24 wk of age) and LT (21 vs. all other ages) at the pen level.
At the pen level, HAY (3.18 ± 0.33) tended to reduce GFP compared to CON
(4.10 ± 0.34) over the ST (P = 0.15) and LT (P = 0.09),
but did not impact the number of SFP, or AP over the ST or LT. More EP
was observed in HAY (3.56 ± 0.14) than BOX (1.61 ± 0.18) throughout the
study (P < 0.0001). More HAY hens perched (P = 0.05)
at 24 wk (0.28 ± 0.12) compared to 21 wk (0.19 ± 0.11), and more HAY
hens (3.69 ± 0.25) performed dust bathing compared to CON (4.14 ± 0.22, P = 0.05) throughout the study. CON performed more struggles (1.13 ± 0.04, P = 0.04) and were quicker to vocalize (4.87 ± 0.07 s, P = 0.05)
during MR than HAY (latency to vocalize(s): 5.16 ± 0.05; number of
struggles: 0.96 ± 0.05), counter-intuitively suggesting CON were less
fearful. Treatment did not affect 5-HT or GC. HAY appears to be a
promising EE for mitigating GFP in non-cage laying hens. Future studies
should examine the impact of EE on individual, rather than group-level
responses. These results suggest that the presence of a hay bale is
stimulating and may reduce GFP while encouraging hens to redirect
pecking towards a dynamic and manipulable EE.
Keywords
- Feather pecking;
- Laying hen;
- Environmental enrichment
- Correspondence
to: 474 S. Shaw Lane, Anthony Hall, Room 1290, Department of Animal
Science, Michigan State University, East Lansing, MI 48824, USA. Tel.:
+1 517 432 1388; fax: +1 517 355 1688.
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