Validation of measuring CO2 production and milk intake by the doubly labelled water technique in piglets

This study was performed to investigate the validity of determining CO2 production of piglets by means of the doubly labelled water (DLW) technique and concomitantly assess the milk intake by dilution of deuterated water. A total of 10 piglets were removed from the sow during the first week of lactation and fed with milk replacer by an artificial sow until weaned at 28 days of age. The piglets were enriched by intraperitoneal injection of DLW at approximately 10 days post partum. Piglets were kept in metabolic cages, and housed either pairwise (three pairs) or in a group of 4 in open-air circuit respiration chambers throughout the study, and the CO2 production was measured 22 h daily by indirect calorimetry and for 3 d by the DLW technique. The milk replacer contained 12.7 % of DM, and 22.9 % protein and 25.7 % fat expressed on DM basis. On average, the piglets had a growth rate of 138 +/- 17 g/d, the milk intake determined by D2O dilution was 891 63 g/d of milk replacer and the daily CO2 production measured by the DLW method was 64.7 L/d. Overall, there was a high agreement between CO2 production assessed by indirect calorimetry and by the DLW method and also between milk intake assessed by weighing the allotted milk compared to that determined by the D2O dilution technique.