Abstract: The purpose of this study was to investigate the effects of tannin from banana leaves on the rumen degradation characteristics in dairy cows and to evaluate the feeding value of banana leaves. The treatments comprised alfalfa (100% alfalfa), alfalfa and banana leaf mixed (50% alfalfa+50% banana leaves), banana leaf (100% banana leaves), alfalfa with polyethylene glycol (PEG) (alfalfa+6% PEG), alfalfa and banana leaf mixed with PEG (alfalfa+banana leaves in a 1∶1 mixture+6% PEG), banana leaf group with PEG (banana leaves+6% PEG). In situ dry matter (DM), neutral detergent fiber (NDF) and crude protein (CP) degradability were determined by incubating the conserved forages in 3 rumen cannulated Holstein cows for 0, 2, 4, 8, 12, 24, 48 and 72 h. The results indicated that compared to alfalfa, banana leaves had lower rapidly degraded fraction (a), slowly degraded fraction (b), fractional disappearance rate (c) and effective degradability (ED, P<0.001) of DM and CP. However, the ED of NDF was similar for alfalfa and banana leaves. Both banana leaves and the alfalfa-banana leaf mixed forage with PEG had greater slowly degraded fractions and ED of DM, NDF and CP, than the two groups without PEG (P<0.001). In summary, the results indicated that tannins in banana leaves inhibited ruminal degradation of the banana leaves, and thus their level of inclusion in mixed diets needs to be controlled when fed to ruminants.

Key words: tannin, banana leaf, rumen degradability, PEG