Effect of feeding spent coffee grounds on the methane production in bovine rumen.

The environmental impact of methane, a greenhouse gas emitted from ruminants, is a pressing issue and methods to control methane emissions from ruminants are being investigated worldwide. In this study, we investigated the effects of the administration of spent coffee grounds (SCG) on methane production in the rumen in two cows. In the control condition (days 1 and 2), the cows were fed a basic diet twice daily (roughage and concentrate), and in the SCG condition (days 1 and 2) sequentially, the cows were fed the same basic diet and administered SCG into the rumen twice daily. The methane and carbon dioxide concentrations in rumen gas were measured via a fistula after feeding on days 2 in both cases of the study. The measurements were made using a newly developed gas measurement system with a portable gas monitor, and data were obtained for the control condition and SCG condition at each measurement time. The methane ratio at each measurement time was calculated from the methane and carbon dioxide concentrations, and compared between the two conditions. Statistical analysis showed no significant difference between the two conditions in the methane ratios after the morning (P=0.108) and afternoon feedings (P=0.345). However, the methane ratios before the morning (P=0.043) and afternoon feedings (P=0.008) were significantly lower in the SCG condition than in the control condition, suggesting that the administration of SCG may suppress methane production in the rumen.