Forty-five crossbred Dorper × Santa Inês lambs were selected to assess the effect of replacing soybean meal by groundnut cake metabolic profile and histopathological evaluation of the kidney and liver tissues. The animals were 5 months old on average with a 24.5 ± 5.3 kg initial body weight which were maintained fed in feedlot with groundnut cake (0, 25, 50, 75, and 100%) as the replacement for soybean meal. Confinement lasted 84 days, and on the last day, the animals were fasted and slaughtered. A completely randomized design with five treatments and nine repetitions was used. Blood samples were collected from the jugular vein of each animal to evaluate the metabolic, protein, energy, and liver profiles of lambs. No effect was observed on protein, energy, or enzymatic profiles, which remained within the normal range for sheep. A histopathological examination was performed, and no deleterious effects from groundnut cake were observed in the liver or kidney tissues. Groundnut cake as a replacement for soybean meal can be used as an alternative protein source up to 100% because it does not affect the metabolic, protein, and energy profiles or the liver and kidney functions of the growing sheep for slaughter.