This study was aimed at evaluating the effects of growth rate during the rearing phase of 13 to 19 months old replacement beef heifers Hereford on body development reared on native pasture. The experiment was conducted from 11/15/2002 to 04/23/2003. The treatments were the three weight gain rates: G600 - 20 heifers (208+1.8kg) submitted to an average growth rate (AGR) of 0.595kg day-1; G700 - 23 heifers (197+1.7kg) with an AGR of 0.637kg day-1 and G800 - 24 heifers (181+1.2kg) with an AGR of 0.723kg day-1. The three AGR aimed for a body weight of 300kg (or 65% of the expected adult weight) at the end of the rearing phase. Treatment effects were determined on body weight, hip height (HH), heart girth (HG), weight:height ratio (WH) and reproductive tract score (RTS). No differences (P>0.05) among treatments were observed on the increment of HH, HG and WH at the end of the experiment. Body weight was highly correlated to HH, HG and WH along the whole rearing phase. The groups G700 and G800 with large growth rates showed higher RTS (P<0.05) than G600 at the end of the rearing phase. The HH and WH measurements taken on beef heifers are not affected by growth rates between 0.600 and 0.730kg day-1 from 13 to 19 months of age. Beef heifers submitted to higher rates of growth (G700 e G800) demonstrated to be more likely to conceive than heifers reared on a lower growth rate (G600), considering the same target weight at the end of the rearing phase.
fall season breeding; heart girth; hip height; native pasture; reproductive tract scoring; weight:height ratio; weight gain
