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The effect of temporary reductions in incubation temperature on growth characteristics and lipid utilisation in the
M Feast1, R C Noble, B K Speake
1School of Biological Sciences, University of Manchester, UK.
Insights
Chick embryo development, including weight gain and tarsus length, halts during cold exposure but resumes normally once optimal temperatures are restored. Repeated cold stress intensifies growth retardation and alters liver lipid profiles.
Area of Science:
- Developmental Biology
- Environmental Physiology
- Avian Biology
Background:
- Embryonic development is sensitive to environmental conditions.
- Temperature significantly influences metabolic rates and developmental processes in ectothermic organisms.
Purpose of the Study:
- To investigate the effects of acute cold exposure on chick embryo development.
- To analyze changes in lipid metabolism and liver composition following temperature stress.
Main Methods:
- Chick embryos were exposed to 22.0 degrees C for defined periods during incubation.
- Measurements included embryo weight gain, tarsus length, yolk lipid transfer, and liver lipid profiles.
- Polyunsaturated fatty acid profiles in the liver were analyzed.
Main Results:
- Embryo growth was suspended during cold exposure but resumed upon return to optimal temperature (37.5 degrees C).
- Two successive cold exposures had an additive effect on growth retardation.
- Cold exposure altered liver lipid concentrations and polyunsaturated fatty acid profiles.
- Yolk lipid uptake was reduced but not completely inhibited.
Conclusions:
- Embryonic development suspension is likely due to a temperature-dependent metabolic reduction (Q10 ≈ 2).
- Cold stress impacts lipid metabolism and nutrient transfer in developing chick embryos.
- These findings highlight the sensitivity of avian embryos to thermal fluctuations.
Abstract:
The effect(s) of finite exposure(s) to 22.0 degrees C on embryo weight gain, 3rd tarsus length, transfer of lipid from the yolk and uptake of specific lipid components by the liver, were measured in the chick embryo. Embryo growth was completely suspended over the period of temperature reduction, but resumed unimpaired when the optimum temperature of 37.5 degrees C was restored. Two successive periods of embryonic exposure to 22.0 degrees C (36 h at d 3 followed by 24 at d 10) were additive in their effect on growth retardation. Embryos subjected to temperature reductions on d 3 of incubation displayed significant changes in lipid concentrations and polyunsaturated fatty acid profiles within the liver when measured at d 18 of incubation. Yolk lipid uptake was significantly reduced but not suspended by embryonic exposure to 22.0 degrees C. It is suggested that the observed suspension of embryonic development was the result of a temperature dependent reduction in metabolism according to a Q10 approximately 2, which is typical of an ectothermic organism.