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Studies on diurnal variations of heat production and the effective lower critical temperature of early-weaned pigs under commercial conditions of feeding and management

Published online by Cambridge University Press:  25 February 2008

K. J. McCracken  and
B. J. Caldwell
K. J. McCracken
Affiliation:
Agricultural and Food Chemistry Research Division, Department of Agriculture, Northern Ireland and The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX
B. J. Caldwell
Affiliation:
Department of Crop and Animal Production, The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX
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Abstract

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1. The heat production of groups of pigs, weaned at 10 d of age, was determined in an open-circuit respiration chamber at various ages between 10 and 33 d at temperatures above and below the lower critical temperature (Tcl).

2. The heat production was lowest on the second or third day post weaning when pigs were given feed increasing by 25 g/pig per d from day 2. There was a marked diurnal pattern in heat production, the lowest values being recorded between 24.00 and 08.00 h.

3. The mean thermal conductance (H/ΔT, kJ/h per m2 per °ΔT, where His total heat production, m2 is the surface area calculated as 0.097 W kg0.633 (Brody, 1945) and °ΔTis the difference between rectal temperature, taken as 39°, and air temperature) below Tcl was calculated as 18.0, 16.9, 18.5 and 21.2 respectively at 10, 17, 24 and 31 d of age. Maximum values of H/ΔT obtained during feeding periods were. on average, 4.5 kJ/h per me per °ΔT higher than the mean values.

4. The maximum value for Tcl during the immediate post-weaning period was 25.9°. The mean Tcl at 17, 24 and 31 d were respectively 21.7, 18.4 and 18.6° for pigs fed almost to appetite.

Type
Papers on General Nutrition
Information
British Journal of Nutrition , Volume 43 , Issue 2 , March 1980 , pp. 321 - 328
Copyright
Copyright © The Nutrition Society 1980

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