Effect of Dietary Tannin on Bio-methane Potential of Dairy Manure

Abstract. Batch experiments were conducted to evaluate the impact of dietary tannins on the anaerobic digestion of dairy manure. Biogas production, methane, carbon dioxide and hydrogen sulfide were measured using a lab scale respirometer system during the mesophilic digestion of diary manure collected from cows fed with 0, 4.5, and 18 g/kg of dietary tannin. Bio-methane potential were calculated. Results showed that dietary tannins affected biogas production. The inhibition is effected by the amount of tannin. 22% of biogas production was significantly reduced with 1.8g/kg dietary tannin. Moreover, by adding 4.5 g/kg and 18 g/kg dietary tannin could significantly reduce H₂S by 32% and 42%, respectively. The bio-methane potential for HT digesters were significantly lower than NT both in 28 days and 42 days retention time.