Methane excretion in the growing pig

Abstract

1. 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 LW0.75) or low (LFL; ME 784 (SE 31) kJ/kg LW0.75) 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 (foil) corresponding to daily intakes of ME of 1339 (SE 11) and 1413 (SE 8) kJ/kg LW0.75 respectively.2. CH4 excretion was measured during 24 h respiration trials in open-air-circulation chambers.3. 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.4. 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 CH, 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 < 0.05). In Expt B the inclusion of soya-bean oil in the basal diet (+oil) reduced CH, excretion by 26% compared with the diet without oil (-oil). The pigs receiving the basal diet excreted 5.2 litres CH4/kg DM and the pigs receiving soya-bean oil 4.3 litres CH4/kg DM, the difference being highly significant (P < 0.001). All differences between Expt A and B in CH4 excretion based on DM intake were highly significant (P < 0.001).5. The results are discussed in relation to gas production in ruminants, rats and humans. It is suggested that flatus production may not only be reduced by changing the composition of the dietary carbohydrates, but also by inclusion of a polyunsaturated oil in the diet of simple-stomached animals and humans.