A study using indirect calorimetry and 16 lactating multiparous Jersey cows (88.4 ± 22.7 DIM; mean ± SD) was conducted to evaluate the utilization of energy in cattle consuming diets containing hydrolyzed feathermeal (HFM). Using a replicated 4 × 4 Latin square design with 35-d periods, treatments included a control (CON) diet, which did not contain HFM, and treatment diets containing 3.3% (DM basis) HFM (LoFM), 6.6% HFM (MdFM), and 9.9% % (DM basis) HFM (HiFM). Diets were formulated such that HFM replaced bloodmeal, and animal energy losses in heat, feces, urine, and milk were collected. A mixed statistical model was used to analyze data with treatment and period as fixed effects and cow within square a random effect. Increasing the concentration of HFM resulted in a quadratic effect (P = 0.041) on DMI (19.6, 20.2, 20.3, and 19.1 ± 0.765 kg for CON, LoFM, MdFM, and HiFM respectively) and a similar trend (P = 0.084) was observed for milk yield (31.7, 32.0, 31.9, and 29.7 ± 1.258 kg). Increasing the concentration of HFM resulted in an increasing linear effect (P = 0.026) on the concentration of milk fat (5.35, 5.23, 5.45, and 5.54 ± 0.216 kg for CON, LoFM, MdFM, and HiFM respectively) but did not affect (P = 0.694) the yield of milk fat, which averaged 1.68 ± 0.069 kg/d . Increasing the concentration of HFM tended to linearly reduce (P = 0.063) the concentration of milk protein (3.34, 3.29, 3.23, 3.23 ± 0.098 for CON, LoFM, MdFM, and HiFM respectively) and linearly reduced (P = 0.004) the yield of milk protein (1.05, 1.05, 1.02, 0.96 ± 0.41 kg). The inclusion of HFM did not affect (P = 0.158) ECM which averaged 39.3 ± 1.415 kg . Apparent total-tract digestion of CP was linearly reduced (P < 0.001) with increasing HFM (63.5, 60.2, 58.4, 57.1 ± 0.81% for CON, LoFM, MdFM, and HiFM respectively). The concentration of NEL tended to increase quadratically (P = 0.068) (1.18, 1.23, 2.27, and 1.26 ± 0.04 Mcal/d for CON, LoFM, MdFM, and HiFM respectively). Results suggest that HFM is a palatable feedstuff, that when used in replace of bloodmeal may result in diets with a greater concentration of energy and maintain FCM, but protein availability may be reduced and this may negatively affect the production of milk protein.