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Crossbred heifers (n=19) were used to determine the effects of feeding Cu, Co, Mn and Zn in amounts greater than recommended by the NRC on ovarian function. Heifers were fed hay ad libitum and individually fed a control (n=9) or trace mineral (n=10) supplement for 109 days. Dry-matter intake, average daily gain, day luteal phase began, length of luteal phase, daily mean progesterone production, follicular phase estradiol production and first wave dominant follicle size were not affected by mineral supplementation. However, heifers in the treatment group had fewer large follicles during the early portion of the estrous cycle.