Comparison of Two Development Systems for March-born Replacement Beef Heifers

A three-year study (2001-2003) was conducted to determine the effect of development system on reproductive performance of first-calf heifers. March-born heifers (n=261) were developed to reach either 55% of mature body weight (MBW) before a 45-day breeding season or 50% of MBW before a 60-day breeding season. Extending the breeding season 15 days for heifers developed to 50% of MBW prior to the first breeding season resulted in equal pregnancy, calving and weaning rates to heifers developed to 55% of MBW. Furthermore, the reduction in development costs in the 50% of MBW system more than offset the reduced income from lower weaning weights caused by later calving dates, resulting in decreased cost to produce one pregnant yearling heifer or 2-year old cow