TY - SER AU - Barnabe,V.H. AU - Barnabe,R.C. AU - Visintin,J.A. AU - Viana,W.G. AU - Casagrande,J.F. AU - Almeida,C.A. TI - Comparative study between phase contrast and differential interference contrast microscopies for evaluation of frozen bull semen KW - TOURO KW - SEMEN KW - MICROSCOPIA ER -