Time-response of relationship of ractopamine feeding on growth performance, plasma urea nitrogen concentration, and carcass traits of finishing pigs - Almeida, Vivian Vezzoni de; Nuñez, Amoracyr José Costa; Schinckel, A. P.; Andrade, Carla de; Balieiro, Júlio Cesar de Carvalho; Sbardella, Maicon; Miyada, Valdomiro Shigueru (Journal of Animal Science, 2013)