RESUMEN
Twenty Nellore bulls (ABW=357.7±9.65kg) were divided into 2 groups: intact and immunocastrated - Bopriva®. After the trial period, the cattle were slaughtered and carcass fat thickness was evaluated, ether extract and fatty acid composition of the longissimus thoracis analyses were performed, and the activity indices of relevant enzymes were calculated. The means were calculated and compared by Student's t-test and Pearson's correlation coefficients (p<0.05). The immunocastrated group showed higher back fat thickness, ether extract, monounsaturated fatty acids (MUFAs), and activity index of Δ(9) desaturase C18 and lower polyunsaturated fatty acids (PUFAs) and n-6 fatty acids when compared to the intact group. The correlations between ether extract and the saturated and monounsaturated fatty acids were positive, and negative with polyunsaturated, n-3, n-6 and PUFA/SFA. Therefore, immunocastration may improve the fatty acid profile in the longissimus thoracis by increasing MUFAs, mainly oleic acid that is the most representative fatty acid in the meat and is considered beneficial to health.