Dynamic aspects of oxygen consumption and carbon dioxide production in swine

Abstract

A model is proposed that allows study of the short-term dynamics of gas exchanges (and heat production) in large open-circuit respiration chambers. The model describes changes in [02] and [C02] in the respiration chamber by a series of differential equations based on animal metabolism and physical characteristics of gas exchange. The model structure was similar for O2 and C02, although model parameters differed. A constant level of O2 consumption (and C02 production) was assumed for resting animals which was different for fed and fasted animals. The adaptation from a fed to a fasting state was described as a first-order process. Physical activity (standing or sitting) was recorded and was included in the model as a constant. Thermic effect of feed comprised the O2 consumption and C02 production related to several relatively rapidly occurring processes after ingestion of a meal (e.g. ingestion, digestion or absorption). In the model, these processes were pooled into a single phenomenon. Model parameters were obtained statistically by comparing model predictions (based on the numerically integrated differential equations) with the observed [O,] and [C02]. The model was evaluated by studying gas exchanges in growing pigs that were fasted for 31 h and re-fed a single meal thereafter. The model fitted the data well over the 47 h measurement range. Traditional methods in which heat production is calculated suffer from noisy data when the interval between observations becomes too short. The proposed method circumvents this by modelling the observed concentration of gases in the respiration chamber rather than the calculated heat production.Energy metabolism: Calorimetry: Modelling Animals produce heat from a variety of metabolic processes such as maintenance, thermoregulation, physical activity and production (e.g. deposition of body tissue, milk production). Indirect calorimetry has played an important role in measuring this heat production in both animals and human subjects. In open-circuit respiration chambers, heat production can be calculated based on measurements of O2 consumption and C02 production without hampering the normal behaviour of the animal (Brown et al. 1984). Due to the size of the respiration chamber in relation to the subject of study, the technique has been of limited use in studying the short-term dynamics of energy metabolism. An instantaneous change in O2 consumption (or C 0 2 production) by the subject results in a small and prolonged response at the gas analyser. The limited sensitivity of gas analysers in combination with the large volume of the respiration chamber and short interval between measurements leads to noisy data when heat production is calculated (McLean & Watts, 1976;Brown et al. 1984;McDonald et al. 1988).The objective of the present study was to propose an alternative method to study the dynamics of gas exchange in open-circuit respiration chambers. In traditional methods, https://doi

Effect of feed intake on heat production and protein and fat deposition in milk-fed veal calves

“…Even though a different exponent was used, BW alone may not be sufficient to describe variation in ME m . In our study, FHP was estimated as the activity-free extrapolated plateau of HP from a modeling approach performed during the fasting day (van Milgen et al, 1997). However, FHP increased when previous FL increased, in agreement with Koong et al (1982) and de Lange et al (2006).…”

“…Gas concentrations (CO 2 , O 2 and CH 4 ) of outgoing air and ventilation rate were continuously recorded (60 times per second) and averaged over 10-s intervals according to procedures described by van Milgen et al (1997) and Labussiè re et al (2008b). The urinary nitrogen losses in the air, recovered in condensed water and outgoing air, were collected according to the methods described by Noblet et al (1987).…”

“…Simultaneous measurement of O 2 and CO 2 concentrations in the respiration chamber, signals of force sensors, meals information (time of distribution and ingested quantity) and physical characteristics of the gas in the chamber were used to calculate the components of HP according to the modeling approach of van Milgen et al (1997). The HP due to physical activity (AHP), to feed intake (short-term thermic effect of feeding, TEF s ) and resting metabolism (RHP) were calculated from respective volumes of O 2 consumption and CO 2 production according to the formula of Brouwer (1965) excluding urinary nitrogen loss.…”

Fasting heat production and metabolic BW in group-housed broilers

“…During the fasting day, the dynamics of HP can be attributed to physical activity and to a gradually declining HP when the broilers transition from an anabolic fed state to a catabolic fasting state (Labussière et al, 2011). As described by van Milgen et al (1997), it is assumed that this transition is asymptotic and the asymptote or minimal HP corresponds to the FHP at zero physical activity. In the statistical estimation procedure, time and the measured physical activity (i.e., the signal from the force sensors) were used as independent variables and the measured O 2 and CO 2 concentrations of the outgoing air from the chamber during the fasting day as dependent variables.…”

“…Access to the feeder was regulated by a cover that was opened or closed according to a time schedule. This meal methodology was implemented to differentiate the short-term and long-term components of the thermic effect of ingested feed (van Milgen et al, 1997).…”