Effects of tannin supplementation on growth performance and methane emissions of Hanwoo beef cows

The objective of this study was to investigate the effects of dietary hydrolysable tannin on growth performance and methane emissions of Hanwoo beef cows. Fifteen cows participated in a seven-week experiment. The cows were stratified by initial methane emissions and assigned to one of two treatments: Control and tannin supplementation. Commercial hydrolysable tannin was top-dressed to a concentrate mix at 3 g/kg based on the dry matter. Enteric methane production was measured for 4 consecutive days at 1 week before and 1, 3 and 7 weeks after the initiation of the experiment using a laser methane detector. The feed intake was measured daily during the methane measurement periods and an additional two days prior to each measurement. The body weight of the cows was measured every 4 weeks. Hydrolysable tannin had no effect (p > 0.05) on body weight, average daily gain, dry matter intake (DMI) and feed conversion ratio. After one week, the methane emission of the tannin supplementation group was 3.66 ppm-m / kg DMI, which was about 3.4% lower (p = 0.078) than that of the control group; however, this tendency disappeared at 3 weeks after the start of the experiment (p > 0.05). The results of this study show that hydrolysable tannin supplementation can reduce enteric methane emissions for a limited period in Hanwoo beef cows. More research, however, is needed to determine the optimal level of hydrolysable tannin supplementation to reduce enteric methane emissions for a longer period without adversely affecting the animal performance of Hanwoo beef cattle.