Purdue University Graduate School
2022.12.16 Yiru Dong PhD dissertation final.pdf (2.29 MB)


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posted on 2022-12-16, 20:25 authored by Yiru DongYiru Dong

    Injurious pecking, aggression, footpad dermatitis and leg abnormalities have been identified as major welfare issues in commercial turkey production, which lead to culling and mortality, downgraded carcass value and economic losses due to decreased productivity and carcass damage. Injurious pecking includes aggressive pecking (head pecking), feather pecking, and cannibalism. Aggressive pecking is related to aggression and is more prevalent in males than females. Feather pecking consists of non-damaging gentle feather pecking and severe feather pecking that can cause feather, skin and tissue damage, and even death in extreme cases. Common methods to control injurious pecking include infrared beak treatment and reduced light intensity, but those methods can result in inconsistent effects on feather condition and negative affect eye development. Footpad dermatitis and leg abnormalities can lead to lameness and an inability of turkeys to access feed and water. 

    Environmental enrichment, which is the modification of the environment of captive animals to improve their biological functioning, is one alternative way of reducing injurious pecking and potentially improving turkeys’ walking ability. In meat-type poultry production, five types of environmental enrichment are usually used, which include social enrichment, occupational enrichment, physical enrichment, sensory enrichment and nutritional enrichment. For turkeys, some types of physical enrichment such as foraging and pecking enrichment have been found to be most effective in reducing injuries caused by injurious pecking and elevated structures (e.g. platform or straw bale) were effective in promoting locomotive exercise. 

    To address some of the gaps in the knowledge regarding the effects of environmental enrichment on turkey behavior, welfare and walking ability, this study examined 1) age-related changes in welfare and gait when turkeys are provided with different types of environmental enrichment; 2) the effects of different types of environmental enrichment on enrichment usage and injurious pecking behavior; 3) specific behaviors and relative location of turkeys when they interact with different types of environmental enrichment.

    Data were collected from a total of 420 beak-trimmed tom turkeys housed in 24 littered pens located in two rooms within the same barn. Birds were randomly assigned to six treatment groups with 4 replicate pens per treatment group, including five enrichment groups (straw bale, platform, platform + straw bale, pecking block and tunnel) and a control group (no additional enrichment provided). Welfare measures (wounds on the head, neck, snood, back and tail; beak abnormalities; feather quality; feather cleanliness; and footpad condition) and walking ability (gait) were assessed at 8, 12, 16 and 19 wk. Postmortem footpad condition was assessed at 19 wk. Behavior of turkeys was video recorded at 8, 12 and 16 wk and analyzed using scan sampling. The proportions of turkeys performing target behaviors were determined every 15 min (07:00 h - 22:00 h). Welfare and gait data were analyzed using PROC LOGISTIC with Firth bias-correction. Behavior data were analyzed using PROC GLIMMIX.

    Better wing feather quality with age was observed in turkeys in the straw bale and tunnel groups. Footpad condition worsened with age for turkeys in all treatment groups except for the straw bale group. Gait worsened with age in all treatment groups while earlier onset of gait problem was observed in turkeys provided with a tunnel or no enrichment (control group). The average proportion of turkeys using the enrichments declined with age. Turkeys provided with a platform + straw bale had the highest levels of enrichment usage, followed by the platform group. Preening and severe feather pecking behavior did not change with age and were unaffected by the type of enrichment provided. Aggressive pecking and gentle feather pecking were not influenced by the type of enrichment provided. Higher average proportions of turkeys were observed performing environmental pecking in the control group than in the platform + straw bale group. Turkeys’ usage of enrichments mainly included resting on top, locomotion, pecking and remaining under the enrichment when they had access to platforms; resting on top, locomotion and pecking when they had access to straw bales or pecking blocks; and remaining in the tunnel and pecking when they had access to a tunnel.

    In conclusion, environmental enrichment showed beneficial effects on turkey wing feather quality, footpad condition and walking ability. Providing tom turkeys with straw bales and tunnels as environmental enrichment can help improve wing feather quality with age and providing straw bales may reduce the development of footpad dermatitis under suboptimal litter conditions. Providing enrichments that can help increase turkey activity and locomotion, including enrichment that can satisfy turkeys’ pecking and foraging needs (straw bale or pecking block) and elevated structures (bale or platform), may be beneficial for turkey walking ability. Multi-functional environmental enrichments, especially a combination of enrichment objects, can promote turkeys’ natural behaviors. Turkeys had the highest enrichment usage when provided with a combination of different enrichment objects (e.g., platform + straw bale) that can serve multiple functions to fulfill their different behavioral needs. Providing a platform only can also achieve high enrichment usage. Turkeys gradually lost interest in interacting with enrichments over time, which may be associated with habituation, destruction of some enrichment objects (e.g. straw bale and pecking block) and fecal contamination on the surface of enrichments. 

    Future research will be valuable in examining the effects of different types of environmental enrichment in various commercial facilities and across different flocks and seasons. Research is needed to examine the effect of enrichments on turkey activity levels and whether there is a relationship between increased activity level and turkey walking ability. In addition, the effectiveness of making periodic changes to the enrichment objects and using unpredicted schedules of presenting the enrichments on habituation will need to be examined.


Degree Type

  • Doctor of Philosophy


  • Animal Sciences

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Marisa A. Erasmus

Additional Committee Member 2

Gregory S. Fraley

Additional Committee Member 3

Janice M. Siegford

Additional Committee Member 4

Fengqing Zhu

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