RELEASE OF METHANE AND OF CARBON-DIOXIDE BY THE PIG

139 observations on methane and on carbon dioxide production obtained in respiratory chambers with sows were evaluated. The animals received common diets without and with different kinds of supplemental bacterially fermentable substrates (BFS) as cellulose, pectin, easily-fermentable carbohydrates, caein, alfalfa meal, and straw meal provided either orally or intracecally. Without particular BFS supplements, 4.8 g methane/d (93 mg/kg live-weight0.75/d) and 2.1 kg carbon dioxide/d (41 g/W0.75/d) were released from on average 1.8 kg dietary dry matter. Methane was only affected by the amount of BFS consumed (CH4, g/d = 2.85 + 13.0.BFS, kg/d) with cellulose and pectin as the most important methane-inducing substrates. Below about 7 % to 9 % BFS in dietary DM, a pronounced reduction in methane production occurred. In sows fed common concentrates, the ratio of methane to carbon dioxide was 1:450. Carbon dioxide was affected by feed intake, live-weight, by the digestibility of the diet, and by the level of body (carbon) retention. Estimates on methane and on carbon dioxide release of growing, pregnant and lactating pigs were provided. The values obtained in pigs were compared to gaseous exchange of other species (man, cattle, sheep).