PSIII-26 - Effects of diets applied with Bokbunja (Rubus coreanus Miquel) on methane emission and growth performances of Korean native steers (Hanwoo)

Abstract: The present study was conducted to demonstrate the effects of Bokbunja (Rubus coreanus Miquel) on enteric methane emission and growth performances of Korean native steers (Hanwoo). The experiment was conducted in a crossover design (2 periods × 2 treatments) with adaptation of diet and chambers for 2wk and measurement of variables for 1wk. Four Hanwoo steers (Average body weight = 460.8 ± 15.8 kg) were allocated to each open-circuit respiration chamber in the National Institute of Animal Science, Wanju, South Korea. The treatments were the following; 1) diets (concentrate: mixed forage = 4:1) with no additives (CON) and 2) diets applied with 5% of Bokbunja (BOK). Steers were fed based on 2% of body weight at 1000 and 1500 h. Blood and rumen fluid were collected after 4 h of the morning feeding on the last day of experimental period to analyze blood metabolites and rumen fermentation characteristics. The methane emission yield of BOK decreased significantly compared to CON (21.2 vs. 23.7 g/kg of DMI; P = 0.027). Dry matter intake (DMI) between treatment groups had no significant differences (P > 0.05), but the average daily gain (ADG) of BOK tended to decrease than CON (0.61 vs. 1.25 kg/day; P = 0.070). Total volatile fatty acids (TVFA) tended to decrease in BOK compared to CON (119.7 vs. 130.2 mM/L; P = 0.080). The contents of blood metabolites had no significant differences between treatment groups (P > 0.05). In conclusion, diets applied with 5% of Bokbunja clearly decreased methane emission yield without negative effects on DMI and blood metabolites, however, there was still a possibility to decrease ADG and TVFA in steers.