The development of thermoregulation in turkey and guinea fowl hatchlings: similarities and differences |
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Authors: | M W Dietz M van Kampen |
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Institution: | (1) Department of Veterinary Basic Sciences, Division Physiology, Utrecht University, P.O. Box 80.176, NL-3508 TD, Utrecht, The Netherlands |
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Abstract: | The development of thermoregulation was studied in turkeys (Meleagris gallopavo, 60.5 g) and guinea fowl (Numida meleagris, 33.5 g) from 2 to 24 h after hatching. Thermoregulation was measured at different ages during 1 h of cold exposure (20°C). Final body temperature rose linearly with age in turkeys, but reached a plateau in guinea fowl between 12 and 16 h. At 2 h after hatch final body temperature was highest in guinea fowl, while at 24 h after hatch there was no difference between the species. The development of mass-specific metabolic rate with age resembled the pattern of final body temperature. At 2 h post-hatch mass-specific metabolic rate was highest in guinea fowl; however, at 24 h post-hatch there was no difference between the species. since mass-specific metabolic rate reached a plateau in guinea fowl at 16 h. In turkeys mass-specific dry thermal conductance decreased with age initially, while in guinea fowl it remained stable. Nevertheless, at both 2 and 24 h after hatch mass-specific wet conductance did not differ significantly between the species. In turkeys mass-specific wet conductance increased initially. This increase in mass-specific wet conductance may be due to the rapid onset of feather growth in turkeys. The O2 consumption per breath doubled during the first 24 h in turkeys but remained stable in guine fowl. This suggests that at least two different developmental patterns of O2 intake exist within Galliformes. The results show that 2 h post-hatch the thermoregulatory ability was lowest in turkeys, despite their larger body mass. However, at 24 h post-hatch the difference between the species was not significant, because the thermoregulatory ability had increased more in turkeys.Abbreviations
B
f
breathing frequency
- BM
body mass
- BMR
basal metabolic rate
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C
D
mass-specific dry thermal conductance
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C
w
mass-specific wet thermal conductance
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HI
homeothermy index
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H
E
evaporative heat loss
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H
B
loss of stored body heat
- MR
metabolic rate
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M
MS
mass-specific metabolic rate
- RH
relative humidity
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I
A
ambient temperature
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T
Bi
initial body temperature
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T
Bf
final body temperature
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VO2
volume oxygen consumed
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VCO2
volume carbon dioxide produced |
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Keywords: | Thermoregulation Metabolic rate Thermal conductance Breathing frequency Galliform hatchlings |
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