Authors : Dan Li, Jiaqi Wang, Fadi Li and Dengpan Bu
Abstract: Methanogens and protozoa in the rumen negatively affect rumen function by wasting ingested energy. It is desirable to modulate rumen fermentation by cost-effective dietary intervention. The objective of this study was to evaluate effects of unsaturated C18 fatty acids (oleic, linoleic and linolenic acids), either alone or in combination with malic acid on in vitro ruminal fermentation, protozoa and Methanobacterium formicicum. Rumen fluid collected from ruminally fisulated lactating Chinese Holstein cows served as the inoculum and the diet consisted of alfalfa hay and corn (50:50). The results showed addition of unsaturated fatty acids tended to increase fermentation pH (p>0.05) and degree of unsaturation of fatty acids tended to affect such effect on the pH (p>0.05). Acetate, butyrate, total VFA, total gas production and methane production decreased (p<0.01) with increasing degree of unsaturation of C18 fatty acids but addition of malic acid did not have any additive or synergistic effect except for propionate which was decreased by the addition of malic acid (p<0.01). Both malate and the unsaturated fatty acids, either alone or in combination, decreased methane production (p<0.01) with combination of these two types of acid further decreasing methane production. Except for oleici acid that decreased population of M. formicicum decreased (p<0.01), either protozoa or M. formicicum was affected by these fatty acid and malic acid. It was concluded that when used together, malic acid and fatty acids could reduce methane emission without negative impairing fermentation in vitro.
Dan Li, Jiaqi Wang, Fadi Li and Dengpan Bu, 2012. Effects of Malic Acid and Unsaturated Fatty Acids on Methanogenesis and Fermentation by Ruminal Microbiota in vitro. Journal of Animal and Veterinary Advances, 11: 2917-2922.