Abstract
An experiment was conducted with four preruminant calves to measure the energy cost and the diurnal pattern of physical activity in tethered, fed calves and to determine whether differences in activity could interfere with the interpretation of circadian changes in heat production. Measurements were carried out in large respiration chambers (3,650 L of inner volume), and a computation method was presented that allowed the calculation of the energy cost of standing for each standing period. This cost averaged 449 cal.kg BW-1.h-1 (SE = 41.6, n = 4). It represented a 23 to 27% increase in heat production above that measured in the lying state. This estimate and its standard error were lower than values obtained by regression (2,131 cal.kg BW-1.h-1, SE = 862.2, n = 8). The energy cost of standing was highest after meal times and lowest at night. These variations could reflect the nonuniform activity patterns of calves while standing. The time spent standing per hour showed the same variations during the day as the energy cost of standing. Noteworthy, the elevated energy expenditure measured in the 1st h after the morning meal was due to activity cost rather than to meal thermogenesis. Standardization of diurnal heat production profiles to a given activity pattern thus seemed to be necessary.
Highlights
In neonatal calves, standing and related spontaneous physical activity may represent an increase in energy expenditure (EE) of up to 46% above lying (Nienaber et al, 1987; Vermorel et al, 1989)
Calves were housed in individual pens that contained wood shavings, at an environmental temperature of 18°C and with no free access to water. They averaged 46.9 kg BW (SE = 2.45) at 14 d of age, and 61.3 kg (SE = 3 . 9 ) at the time of measurements when calves were approximately 33 d old. Because these calves were simultaneously used in a study on in vivo tissue energy metabolism they were surgically equipped at the age of 14 d with blood catheters as described in Durand et al (1988) for splanchnic
Increasing attention has recently been focused on the influence of standing time and its associated energy cost on the interpretation of whole animal or tissue EE
Summary
In neonatal calves, standing and related spontaneous physical activity may represent an increase in energy expenditure (EE) of up to 46% above lying (Nienaber et al, 1987; Vermorel et al, 1989). The activity pattern of animals and probably the energy cost of standing (ECS) vary within the day (Toutain et al, 1977) It may, contribute to variations in EE to a larger extent than do the interanimal differences (van Es, 1972). The objectives of the present study were to measure the energy cost and the diurnal pattern of physical activity of preruminant calves and to determine whether differences in activity could interfere with the interpretation of the circadian changes in EE. This trial was conducted on tethered, fed preruminant calves for which data are limited.
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