# SUPPLEMENTATION WITH PROTEIN SOURCES IN THE FINISHING STAGE OF BEEF HEIFERS: A BIOECONOMICAL STUDY

The purpose of this study was to evaluate biological and economically the use of three protein sources (soybean meal (SM), cottonseed (CS) or turnip cake (TC)), in the supplement formulation (1.0 % of body weight (BW)) in the finishing stage of heifers grazing Marandu grass pastures during the dry season. This experiment was conducted in the city of Potirendaba, São Paulo State, and the chemical analyses were performed at the Londrina State University, Paraná State. The experimental area had six hectares, divided into three paddocks, each one with six crossbred heifers (Simmental × Nellore), initial BW of 210 ± 8.34 kg, and age of 15 ± 3 months. Economic analysis was performed using the method of partial budgeting. The experimental design was completely randomized, with six replicates per treatment (n = 18). Analysis of variance was conducted, and means were compared by Tukey test (P <0.05). Animals supplemented with TC exhibited lower weight gain (SM = 0.81, CS = 0.76 and TC = 0.40 kg / animal / day; P <0.05). Negative changes were observed in net income for the CS supplements (US $-22.15 / animal) and TC (US$ -1.96 / animal) relative to the SM supplement, which showed better biologic and economic results.