Fifty cycling Mediterranean buffalo heifers between 24 and 30 months of age were maintained on a Brachiariadecumbens pasture with mineral supplementation fromApril to July. The experiment was conducted at the Centrode Biotecnologia em Reproduc¸ ão Animal do Departamentode Reproduc¸ ão Animal da Faculdade de Medicina Veter-inária e Zootecnia da Universidade de São Paulo – Campusde Pirassununga (São Paulo, Brazil; latitude 21◦59South,longitude 47◦26West).