Synchronising oestrus with oestradiol benzoate after using a two‐dose prostaglandin treatment to synchronise luteolysis in dairy heifers

Abstract

Objective To compare the reproductive performance and pattern of onset of oestrus in dairy heifers in which oestrous cycles were synchronised with two doses of prostaglandin (PG) F2aL and oestrus was synchronised with oestradiol benzoate (ODB). Procedure Dairy heifers in two herds (herd A, n=192; herd B, n = 267) were treated with two doses of an analogue of PGF2aL (cloprostenol, 375 mUg, IM) 12 days apart. Heifers not detected in oestrus 48 h after the last dose of PGF2aL were either left untreated (No ODB, n=147) or treated with ODB (0.75 mg IM, n = 126). Onset of oestrus was monitored at 0, 24, 48, 80, 96 and 120 h after the last dose of PGF2aL Heifers were inseminated on detection of oes..