Herbal feed additives containing tannins: impact on in vitro fermentation and methane mitigation from total mixed ration

Abstract

Total mixed ration (TMR) containing roughage and concentrate mixture in a 65: 35 ratio on dry matter (DM) basis wassupplemented with herbal feed additives [(HFAs); Acacia catechu (Katha), Areca catechu (Supari), and Acacia nilotica (Babul)] at 0–4%on DM basis to assess their impact on fermentation pattern and methane production by using in vitro gas production technique. Arecacatechu had the highest (P < 0.01) concentration of condensed tannins (CTs), saponins, and vitamin C as compared to other HFAs. Thenet gas production (NGP), digestibility of NDF and true OM, and ME availability, partitioning factor (PF), volatile fatty acids (VFAs),and microbial biomass production were higher (P < 0.01) at 24 h as compared to t-half incubation, irrespective of type and level ofHFAs supplemented. Acacia nilotica had an edge over Acacia catechu with respect to digestibility of nutrients and ME availability. VFAsproduction and efficiency of rumen fermentation was the highest from the Areca catechu-supplemented TMR. Irrespective of type ofHFAs and incubation period, the digestibility of NDF and that of true OM were highest (P < 0.01) at the 1% level of supplementation, butdepressed thereafter. Amongst HFAs-supplemented groups, VFA production and fermentation efficiency were highest at the 2% level.The results conclusively revealed that supplementing Areca catechu and Acacia nilotica at 2% of TMR (DM basis) inhibited the methaneproduction, without affecting the fermentation pattern.