POTENTIAL OF VARIOUS FATTY FEEDS TO REDUCE METHANE RELEASE FROM RUMENFERMENTATION IN-VITRO (RUSITEC)

The effects of coconut oil and whole crushed oilseeds (rapeseed, sunfl ower seed and linseed) on rumen fermentation, as well as on methane an d hydrogen release, were evaluated in vitro employing the rumen simula tion technique (Rusitec). A low-fat diet served as the negative contro l and a diet with rumen protected fat as the positive control. By usin g two different proportions of concentrate in the diet, 6% and 9% of t otal lipids were supplied with each of the five fat supplemented diets , whereas the control diets contained about 3% total lipids. The 12 di ets were provided at daily amounts of 11 g and 22 g dry matter. Rumen- protected fat as well as rapeseed had small effects on fermentation pa ttern and methane formation, which presumably resulted from the exchan ge of carbohydrates by fat. In contrast, coconut oil, sunflower seed a nd linseed significantly reduced protozoa count and methane release. A n increased fat supply by the higher concentrate proportion further su pported the suppressing effects of these types of fat on protozoa and methane. Coconut oil completely eliminated protozoa from rumen fluid a fter four to nine days of application, and this period was shorter by more than 30% on average at the higher level of supply. As compared wi th the low-fat treatment, coconut oil suppressed methane by 43% with m edium and 57% with high concentrate level. The maximum methane reducti on with sunflower seed and linseed accounted for about 40%. An increas e in hydrogen release was found with coconut oil and oilseeds which, h owever, was considerably lower than the hydrogen quantities that were less incorporated into methane. In these situations, hydrogen recovery , as calculated from hydrogen balance, was reduced. (C) 1998 Elsevier Science B.V.