부산대학교 도서관

Simple Summary: This study investigated the effect of varying the levels of dietary crude protein (CP) in concentrate mixes on growth performance, rumen characteristics, digestibility, blood metabolites, and methane emissions in fattening Hanwoo steers. The experiment was conducted for 12 weeks by feeding four concentrate mixes with different levels of dietary CP (15, 18, 19, and 21% of CP dry matter basis). There was a linear increasing trend in the average daily gain (ADG) with increasing dietary CP (p = 0.066). The increase in CP levels also influenced the characteristics of the rumen fluid, leading to increased concentrations of rumen ammonia and an increase in the proportion of butyrate and valerate (p < 0.05) while decreasing the propionate proportion (p = 0.004). The blood urea increased (p < 0.001) and the blood non-esterified fatty acids and cholesterol decreased (p ≤ 0.003) as the dietary CP increased. The methane concentration from eructation per intake (ppm/kg), forage neutral detergent fiber (NDF) intake, total NDF intake, and ADG exhibited linear decreases (p ≤ 0.014) across diets. In summary, increasing the dietary CP to 21% in concentrates tended to increase the ADG, reduce the propionate, and increase the butyrate. The methane from eructation showed a tendency to linearly decrease with higher CP. This study aimed to investigate the effect of varying levels of dietary crude protein (CP) on growth performance, rumen characteristics, blood metabolites, and methane emissions in fattening Hanwoo steers. Twenty-four steers, weighing 504 ± 33.0 kg (16 months old), were assigned to four dietary treatments with different CP concentrations (15, 18, 19, and 21% of CP on a dry matter (DM) basis). A linear increasing trend in the average daily gain (ADG) was observed (p = 0.066). With increased dietary CP levels, the rumen ammonia concentration significantly increased (p < 0.001), while the propionate proportion linearly decreased (p = 0.004) and the proportions of butyrate and valerate linearly increased (p ≤ 0.003). The blood urea exhibited a linear increase (p < 0.001), whereas the blood non-esterified fatty acids and cholesterol showed a linear decrease (p ≤ 0.003) with increasing dietary CP. The methane concentration from eructation per intake (ppm/kg), forage neutral detergent fiber (NDF) intake, total NDF intake, and ADG exhibited linear decreases (p ≤ 0.014) across the treatments. In conclusion, increasing the dietary CP up to 21% in concentrates demonstrated a tendency to linearly increase the ADG and significantly decrease the propionate while increasing the butyrate. The methane concentration from eructation exhibited a tendency to linearly decrease with increasing dietary CP. [ABSTRACT FROM AUTHOR]