Evaluation of biogas production from manure of hybrid and local breed cows fed with different types of feeding practices

ABSTRACT

This study aimed to evaluate the biogas production from the manure of hybrid and local breed cows fed with different types of feeding practices. The feedstock and digestive composition were measured to determine their effects on biogas production. The batches were prepared form manure of hybrid and local breed cows fed with roughages and mixed ration (roughages and concentrate) adding Inoculum (I) and with a total weight of 200 g. Four experimental groups (T1, T2, T3 and T4) were set up using mixing ratios of CM: H₂O: I (25: 25: 50). The digesters were set up at ambient temperature for 40 days of Hydraulic Retention Time (HRT) using a water displacement method to monitor biogas production in the proto-type digesters. The biogas yield from the manure was found 250.90 Nml/g VS for T1, 176.50 Nml/g VS for T2, 208.25 Nml/g VS for T3 and 180.88 Nml/g VS for T4, respectively. The average CH₄ and CO₂ concentration (% vol.) in biogas were found 53% and 47% for T1, 55% and 45% for T2, 52% and 48% for T3, 53% and 47% for T4, respectively. The content of H₂S was not found in this study. The study concluded that the overall biogas production was higher in the manure of hybrid cows fed with roughages. However, the biogas production was also higher in the manure of local breed cows fed with roughages than mixed ration. The results indicated that C, N, P, K and S values were relatively lower in this study.

Keywords: Biogas, CH₄, hybrid and local breed cows, prototype digester, HRT.