Beta-acid extract of hops was fed to finishing heifers (n = 80; 389 ± 23.6 kg initial BW) to assess effect on growth performance and ruminal fermentation. Heifers were randomly assigned to individual pens and fed diets based on steam-flaked corn and corn gluten feed for 147 d. Treatments consisted of a control (no additive); monensin (Elanco Animal Health, Greenfield, IN) fed at 33 mg/kg diet DM; and β-acid extract of hops (DSM Nutritional Products, France) fed at 10, 25, or 50 mg/kg diet DM. Ruminal fluid was collected on d 44 and 86 by rumenocentesis for analysis of VFA and NH3 concentrations. Feeding β-acid or monensin did not alter ruminal fermentation, growth performance, DMI, or gain efficiency (P > 0.05). Performance data were analyzed using a mixed model with diet as a fixed effect and weight block as a random effect. Pair-wise comparisons were performed using the PDIFF option. Categorical data were analyzed using the Glimmix procedure with diet as a fixed effect, weight block as the random effect, and feedlot pen as the experimental unit. In conclusion, under conditions of this experiment β-acid extract did not alter performance or ruminal fermentation. Table 1.

Item	Control	Beta acid extract, mg/kg DM			Monensin	SEM
10	25	50
DMI, kg/d	9.90	9.91	9.89	9.98	9.94	0.38
G:F	0.1394	0.1405	0.1465	0.1394	0.1457	0.0049
NH3, mM	0.40	0.40	0.47	0.37	0.19	0.105