Calving dairy heifers at 2 years of age, with the achievement of high levels of maturity (live weight) at service (65%) and calving (85 %) increases lifetime productivity (Margerison and Downey, 2005). Recent research into dairy heifer nutrition has focused on increasing calf development, live weight gain and development of stature, while minimising tissue fat deposition, particularly in mammary parenchyma (Serjrsen, 2005). The use of increasing feeding levels and growth rates for dairy heifers during the prepubertal period have been the focus of recent research and much of this has involved differing sources and levels of energy and protein (Hill, 2005; Tannan, 2005) and the use of probiotics and natural plant extracts to replace antimicrobials. In addition to these considerations, the world milk supply dynamics and increasing global demand for milk results in the need to consider using lower levels of whole milk and alternatives to skim milk products for dairy heifer rearing. The aim of this research was to compare the effect of offering differing levels of whole milk and a combination of plant extracts on the growth, development and weaning age of New Zealand (NZ) Holstein Friesian and NZ Holstein Friesian dairy heifers.