Methane excretion in the growing pig.

Total methane excretion (CH4 in breath + flatus) was measured in two experiments with thirty-six castrated male pigs (Danish Landrace) during the growth period from 20 to 120 kg live weight (LW). In Expt A, twenty-eight pigs were fed on a commercial diet alternately at high (HFL; metabolizable energy (ME) 1234 (SE 41) kJ/kg LW 0.75) or low (LFL; ME 784 (SE 31) kJ/kg LW 0.75) feed levels in different weight classes. In Expt B, eight pigs were constantly fed on a semi-purified diet at HFL without (-oil) or with 90 g soya-bean oil/kg diet (+oil) corresponding to daily intakes of ME of 1339 (SE 11) and 1413 (SE 8) kJ/kg LW 0.75 respectively. CH4 excretion was measured during 24 h respiration trials in open-air-circulation chambers. About 1 litre CH4 was excreted per day at 20-25 kg LW increasing to a maximum of 12 litres at 120 kg LW, which corresponded to no more than 1.2% of dietary gross energy. In Expt A, CH4 excretion increased linearly with LW, while in Expt B the increase was linear until about 70 kg LW, when it reached a plateau. On average LFL reduced CH4 excretion by 23% compared with HFL. When related to dry matter (DM) intake, however, the pigs on LFL excreted 3.1 litres CH4/kg dietary DM and those on HFL 2.5 litres CH4/kg dietary DM, the difference being significant (P less than 0.05). In Expt B the inclusion of soya-bean oil in the basal diet (+oil) reduced CH4 excretion by 26% compared with the diet without oil (-oil).(ABSTRACT TRUNCATED AT 250 WORDS)