RESUMO
Monensin sodium is one of the most common ionophores used in livestock feeding; however, ionophores are condemned by organized consumer groups. Bioactive compounds from plants found in the seasonally dry tropical forest have similar mechanisms of action as ionophores. The aim was to investigate the effects of replacing monensin sodium with phytogenic additives on the nutritional efficiency of beef cattle. Five 14-month-old Nellore bulls (average body weight 452.68 ± 42.60 kg) were used in the study. The experiment was designed as a 5 × 5 Latin Square (five treatments and five 22-day experimental periods). Within each period, 15 days were used for adaptation of animals to experimental conditions and 7 days for data collection. Bulls were fed a control diet (without additives), monensin (a diet containing monensin sodium 40% as a synthetic additive), and three diets containing phytogenic additives prepared from Anadenanthera macrocarpa (Benth) Brenan, Mimosa tenuiflora (Willd) Poiret, or Prosopis juliflora (Sw.) DC. Nutritional efficiency was assessed through feed intake, nutrient digestibility, feeding behavior, and hematological parameters. Monensin and phytogenic additives did not influence (P > 0.05) feeding behavior or hematological parameters, but the nutrient intake was highest for bulls supplemented phytogenic additives (P < 0.05). Monensin supplementation did not influence (P > 0.05) feed intake. The phytogenic additives and monensin sodium increased (P < 0.05) the nutrient digestibility. Therefore, the phytogenic additives from P. juliflora, A. macrocarpa, and M. tenuiflora can be recommended to enhance the nutritional efficiency of confined Nellore cattle.