The effect of progesterone concentrations during superovulation of Holstein heifers in a randomized trial oleh J.C.S. Marques, J.P.O. Maciel, J. Denis-Robichaud, R.S. Conceicao, A.M. Bega, S. Moore, M.A. Sirard, C.F. Baes, R.L.A. Cerri