Author : Jayanegara, Anuraga

Summary : The role of tannin on ruminant production performance, reduction in enteric methane emission, and changes in rumen fatty acid profile were investigated. Specifically, the objectives were to screen and characterize common forage plants based on tannin and other chemical properties (Experiment 1), determine the rumen fermentation changes as affected by mixture of low and high tannin plants (Experiment 2), determine the effects of purified condensed and hydrolyzable tannins as feed additives on rumen fermentation and microbial population (Experiment 3), and determine the effect of tannin on the growth of beef cattle (Experiment 4).

Results revealed that plants rich in tannin have the property to mitigate methane emission. All phenolic fractions, i.e., non-tannin phenols, condensed tannins (CT), and hydrolyzable tannins (HT) appeared to contribute to suppressing CH4 formation as shown by negative correlations of the fractions in plants and CH4/total gas or CH4/digestible OM. Apart from decreasing CH4 emission linearly, combining plants rich in tannin with a high quality forage plant with negligible tannin provided additional benefits due to the presence of synergistic associative effects, which further decreased CH4. Incubation of tropical plants with additional linseed oil suggests the ability of plant tannin in modulating FA biohydrogenation by decelerating the process as indicated by lower disappearance of C18:3 n-3 and C18:2 n-6.

All tannin extracts decreased methane concentration either linearly or quadratically, but their magnitudes were different being greater for the HT than the CT, and correlated with their protein precipitation capacity. All purified HT and CT decreased total methanogen population. The addition of tannin at 25 g/d in the diet of crossbred Brahman cattle resulted in a 29.2 percent increase in growth rate from 1.20 kg/d to 1.55 kg/d. In conclusion, plant tannin in ruminant diet was able to modulate methanogenesis and fatty acid biohydrogenation and improve growth performance of cattle.