The correct addition of feed additives should be controlled by the working accuracy test of the production plant for compound feed or premixes, which includes the test of the carry-over level. According to market requirements the carry-over should be less than 4 per cent for manufacture of compound feed and less than 1 per cent for premix plants. Considering the different causes of additive carry-over recommendations for stabilization of the mixtures and avoidance of carry-over and cross contamination are given. The addition of liquid formulated additives at the end of the production line can reduce the carry-over level. Unprofessional admixing of liquid components in the main mixer causes the formation of agglomerates and deposits as sticks and crusts which cannot be compensated by rinsing batches. Test results show the bad suitability of ribbon mixer for admixing of liquid components.