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Group selection for adaptation to multiple-hen cages: hematology and adrenal function
P Y Hester1, W M Muir, J V Craig
1Department of Animal Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
Poultry Science
|November 1, 1996
Summary
Selected White Leghorn chickens show better adaptation to crowded cages, exhibiting fewer stress responses like heterophilia compared to control and commercial lines. This indicates improved resilience in social competition environments.
Area of Science:
- Animal Science
- Avian Physiology
- Animal Behavior
Background:
- Intensive poultry farming often involves housing multiple birds in single cages, leading to social stress.
- Selection for improved survivability and productivity in crowded conditions is crucial for animal welfare and economic viability.
- Understanding the physiological responses of chickens to social competition and environmental stressors is essential.
Purpose of the Study:
- To evaluate the hematological and adrenal responses of a selected line of White Leghorns adapted to multiple-hen cages.
- To compare the stress resilience of selected, control, and commercial chicken lines under different housing and environmental conditions.
- To test the hypothesis that selected hens would exhibit reduced stress responses to various challenges.
Main Methods:
- Three lines of chickens (selected, control, commercial) were housed in single or multiple-hen cages.
- Birds were subjected to cold and heat stress challenges at different ages.
- Hematological parameters (packed cell volume, heterophil to lymphocyte ratio) and plasma corticosterone levels were measured.
Main Results:
- The selected line showed quicker adaptation to multiple-hen cages, indicated by packed cell volume changes.
- Control and commercial lines exhibited heterophilia and increased heterophil to lymphocyte ratios under social competition, unlike the selected line.
- Plasma cholesterol and corticosterone levels were not significantly affected by genetic stock or environmental interactions.
- Stress responses in the selected line were not consistently less intense across all conditions and ages.
Conclusions:
- The selected line of White Leghorns demonstrated improved physiological adaptation to multiple-hen cage environments.
- Evidence suggests better adaptation to social competition in the selected line, though stress response intensity varied.
- Further research may be needed to fully elucidate the consistent stress resilience mechanisms in selected poultry lines.