HEIFER DEVELOPMENT UNDER A WESTERN RANGE ENVIRONMENT - CALVING AND WEANING

A total of 101 crossbred heifers (average bodyweight [BW] of 346 kg) w ere used to evaluate pelvic area measurement, incidence of dystocia, r ebreeding success, and weaning management on a western range environme nt. Pelvic area of heifers was measured at 12 months of age. Data indi cated that 150-square cm pelvic area (assistant rate of 8%) would be a better selection criteria for heifers grown in the western range envi ronment because of a slower growth rate. Adjusted 205-day weaning weig hts indicated a 9.5-kg (P < 0.05) advantage for late weaning (LW) comp ared to early weaning (EW) calves; however, 77% of the EW heifers had a body condition score (BCS) of five or better compared to 29% in the LW heifers (P < 0.05) indicating that weaning management is a critical factor for heifers grazing under a western range environment.