Radiotelemetry was 90% efficient and 100%accurate for estrous detection. Intervals between the PGF2dose and the beginning of syn-chronized estrus (40.7 ± 10.9 vs. 56.7 ± 12.8 h) or ovulation (70.0 ± 11.3 vs. 85.6 ± 12.5 h)were shorter (P < 0.05) for heifers receiving PGF2during the early luteal phase