Effect of tamarind (Tamarindus indica) seed husk tannins on in vitro rumen fermentation

This study was conducted to determine the effect of tamarind seed husk (TSH) as a source of tannin on various parameters of rumen fermentation in vitro. The TSH contained 14% tannin (DM basis). The biological interference of TSH tannin on rumen fermentation was assessed using polyethylene glycol (PEG) 6000 as an indicator. Three compound feed mixtures (CFM) were prepared either without TSH (CFM-I), with 2.5% TSH (CFM-II) and with 7.5% TSH (CFM-III). Parameters studied were in vitro gas production with PEG, rate of substrate degradation, and microbial protein synthesis. Addition of PEG to TSH resulted in an increase in gas production from 5.5 to 16.5 ml per 200 mg DM. Presence of TSH tannin depressed cumulative gas production by 16.8% in CFM-II, and by 29.2% in CFM-III during initial stages of fermentation (i.e. at 8 h). Rate of substrate disappearance (T1/2) was 14.4, 17.6 and 20.5 h in CFM-I, CFM-II and CFM-III, respectively. Irrespective of the carbohydrate source, presence of TSH tannin improved the efficiency of microbial protein synthesis in vitro. Thus, TSH is a natural source of tannin that can be used to beneficially manipulate rumen fermentation.