TY - JOUR

T1 - The oral 13C-bicarbonate technique for determination of energy expenditure in dogs

T2 - dietary and environmental factors affecting the respiratory quotient and 13C recovery factor

AU - Marcussen, Caroline

AU - Gabel, Stephanie

AU - Meyer, Ann Kristin

AU - Tauson, Anne Helene

N1 - Funding Information: Financial support from Royal Canin is gratefully acknowledged. The authors would also like to thank the dog owners who kindly lent their dogs for this study, Marlene Nytofte Nielsen for providing technical assistance with operating the respiration chambers and Lotte Ørbæk for conducting the chemical feed analysis. Publisher Copyright: © 2022 Informa UK Limited, trading as Taylor & Francis Group.

PY - 2021

Y1 - 2021

N2 - The oral 13C-bicarbonate technique (o13CBT) can be used for short-term measurements of CO2 production (RCO2) and energy expenditure (EEx). The method relies on appropriate estimates for the respiratory quotient (RQ) and recovery factor (RF) of 13C. Four Retriever dogs were included in four experiments to validate the o13CBT against indirect calorimetry (IC), and determine RQ and RF; Expt. 1: feeding different protein:fat:carbohydrate ratios [in % of metabolisable energy]: 25:33:42 in a maintenance (Mnt.) diet; 38:26:36 in a high-protein high-fibre (HFibre) diet and 27:56:17 in a high-fat (HFat) diet, simultaneously with start of measurements (T0); Expt. 2: the Mnt. diet at T0 or 4 h postprandial (T4); Expt. 3: T4 at different ambient temperatures, 22°C and 15°C; Expt. 4: T4 after 1 h physical activity. The RCO2 and EEx were determined from the respiration chamber measurements made simultaneously with IC and the o13CBT (o13CBTonline), and in Expts. 1 and 2, also on two consecutive days using o13CBT with collection of breath into breath bags (o13CBTbreathbags). The RQ values obtained at T0 reflected dietary compositions, with the highest least square mean (LSM) of 0.954  for the Mnt. diet, 0.905 for the HFibre and 0.877 for the HFat diet (p < 0.05). An increased interval between meal and measurement period decreased RQ significantly (p < 0.05) in Expt. 2, LSM being 0.954 at T0 and 0.909 at T4. Ambient temperature (Expt. 3) and physical activity (Expt. 4) did not influence postprandial RQ. The RF values were not significantly affected by diet (Expt. 1). Measurements starting at T0 (Expt. 2) resulted in higher (p < 0.05) RF values than at T4 (LSM = 0.971 and 0.836, respectively). The ambient temperatures (Expt. 3) did not influence postprandial RF. However, when dogs were physically active prior to measurements (Expt. 4), RF values (LSM = 1.019) were higher (p < 0.05) than when resting only (LSM = 0.836). Calculations based on RQ and RF determined in each experiment resulted in RCO2 and EEx values which were not different regardless of method used, except for Expt. 1 where EEx-values [kJ · kg BW–0.75 · d–1] were higher (p < 0.05) when measured with o13CBTbreathbags (460) than by IC (421) and o13CBTonline (420). Provided accurate RQ and RF values, the o13CBTbreathbags can be used as an independent and minimally invasive research tool to determine EEx in dogs under carefully standardised conditions.

AB - The oral 13C-bicarbonate technique (o13CBT) can be used for short-term measurements of CO2 production (RCO2) and energy expenditure (EEx). The method relies on appropriate estimates for the respiratory quotient (RQ) and recovery factor (RF) of 13C. Four Retriever dogs were included in four experiments to validate the o13CBT against indirect calorimetry (IC), and determine RQ and RF; Expt. 1: feeding different protein:fat:carbohydrate ratios [in % of metabolisable energy]: 25:33:42 in a maintenance (Mnt.) diet; 38:26:36 in a high-protein high-fibre (HFibre) diet and 27:56:17 in a high-fat (HFat) diet, simultaneously with start of measurements (T0); Expt. 2: the Mnt. diet at T0 or 4 h postprandial (T4); Expt. 3: T4 at different ambient temperatures, 22°C and 15°C; Expt. 4: T4 after 1 h physical activity. The RCO2 and EEx were determined from the respiration chamber measurements made simultaneously with IC and the o13CBT (o13CBTonline), and in Expts. 1 and 2, also on two consecutive days using o13CBT with collection of breath into breath bags (o13CBTbreathbags). The RQ values obtained at T0 reflected dietary compositions, with the highest least square mean (LSM) of 0.954  for the Mnt. diet, 0.905 for the HFibre and 0.877 for the HFat diet (p < 0.05). An increased interval between meal and measurement period decreased RQ significantly (p < 0.05) in Expt. 2, LSM being 0.954 at T0 and 0.909 at T4. Ambient temperature (Expt. 3) and physical activity (Expt. 4) did not influence postprandial RQ. The RF values were not significantly affected by diet (Expt. 1). Measurements starting at T0 (Expt. 2) resulted in higher (p < 0.05) RF values than at T4 (LSM = 0.971 and 0.836, respectively). The ambient temperatures (Expt. 3) did not influence postprandial RF. However, when dogs were physically active prior to measurements (Expt. 4), RF values (LSM = 1.019) were higher (p < 0.05) than when resting only (LSM = 0.836). Calculations based on RQ and RF determined in each experiment resulted in RCO2 and EEx values which were not different regardless of method used, except for Expt. 1 where EEx-values [kJ · kg BW–0.75 · d–1] were higher (p < 0.05) when measured with o13CBTbreathbags (460) than by IC (421) and o13CBTonline (420). Provided accurate RQ and RF values, the o13CBTbreathbags can be used as an independent and minimally invasive research tool to determine EEx in dogs under carefully standardised conditions.

KW - C recovery

KW - activity

KW - dogs

KW - Energy expenditure

KW - respiratory quotient

KW - stable isotopes

KW - temperature

U2 - 10.1080/1745039X.2021.2015986

DO - 10.1080/1745039X.2021.2015986

M3 - Journal article

C2 - 35232290

AN - SCOPUS:85125992952

VL - 75

SP - 489

EP - 509

JO - Archives of Animal Nutrition

JF - Archives of Animal Nutrition

SN - 1745-039X

IS - 6

ER -