Comparing Tea Leaf Products and Other Forages for In-vitro Degradability, Fermentation, and Methane for Their Potential Use as Natural Additives for Ruminants


Tea leaves are a rich source of plant secondary metabolites such as tannins and saponins that have the potential to manipulate rumen fermentation and to lessen methane (CH4) production.Samples of green tea (GTL), black tea (BTL), their spent leaves after water extraction (SGTL and SBTL), ryegrass hay (RH), ryegrass silage (RS), paddy straws (PS), barley straws (BS), and wheat straws (WS) were compared for their rumen in-vitro organic matter degradability (IVOMD, g/kg DM), pH, ammonia (NH3, mg/L), total volatile fatty acids (tVFA, mmol/L), total gas production (tGP, L/kg OM), and methane output (CH4,L/kg OM) after 28h incubation with buffered rumen fluid under anaerobic conditions at 39oC in glass syringes. One-way ANOVA on Minitab 16 was used to examine differences between products at P<0.05 for four replicate samples. There were no differences between tea leaf products, RH and RS but the straws tended to have lower IVOMD compared with tea leaf products and other forages. GTL produced the lowest NH3 followed by BTL, SGTL, SBTL, and other forages. There were no differences between most tea leaf products, RH, RS, and the straws for tVFA concentration but PS and WS produced the lowest tVFA. GTL, SGTL, and RH had higher tGP than BTL, SBTL, and the straws but they had a lower tGP than RS. GTL, BTL, and SBTL produced similar levels of CH4 as the straws but this was less than RS and SGTL. The results suggest that if tea leaf products are included in the straw-based diets as natural feed additives, they may improve degradability, tVFA, NH3,and tGP production without increasing CH4 output. Low NH3 production for tea leaf products could be the sign of more by-pass protein to be absorbed in small intestine.

Keywords: Tea leafproducts, in-vitro measurements, and ruminants.

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