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Oxygen and avian eggshell formation at high altitude
S C Hempleman1, T P Adamson, D E Bebout
1Department of Medicine, University of California, San Diego, La Jolla 92093-0623.
Respiration Physiology
|April 1, 1993
Summary
High altitude chickens exhibit reduced eggshell conductance due to hypoxia. Physiological acclimatization, not genetic adaptation, explains this change in eggshell properties.
Area of Science:
- Avian physiology
- Environmental adaptation
- Reproductive biology
Background:
- Birds at high altitudes often lay eggs with lower water vapor conductance.
- The reasons for this are debated, with hypotheses including physiological acclimatization and genetic adaptation.
Purpose of the Study:
- To investigate physiological acclimatization in eggshell conductance.
- To quantify the impact of reduced oxygen availability (hypoxia) on eggshell properties.
Main Methods:
- Ten laying hens (Gallus domesticus) were subjected to three conditions: 3800 m altitude, 3800 m with supplemental oxygen, and 1200 m altitude.
- 573 eggs were collected over 17 weeks to analyze shell conductance, pore area, and thickness.
Main Results:
- Eggshell conductance, pore area, and thickness were significantly reduced at 3800 m compared to lower altitudes or when supplemental oxygen was provided.
- The hens' physiological response to changes in altitude and oxygen levels showed a time lag of approximately 2.5 weeks.
Conclusions:
- Physiological acclimatization of eggshell conductance occurs in chickens exposed to high altitude.
- Hypoxia appears to be the primary stimulus for these changes in eggshell formation.