This experiment was conducted during the 2008/2009 and 2009/2010 spring-summer breeding seasons. A total of 540 suckled cows (370 Nelore [Bos indicus] and 170 crossbred [Bos indicus Bos taurus; three quarters Nelore) from a commercial beef farm in the state of Mato Grosso, Brazil were enrolled in this study. All cows were maintained on Brachiaria brizantha pastures with free access to water and given mineral supplementation. The mineral mix was labeled to contain