Premium
Synchronising oestrus with oestradiol benzoate after using a two‐dose prostaglandin treatment to synchronise luteolysis in dairy heifers
Author(s) -
CAVALIERI J,
HEPWORTH G.,
FITZPATRICK LA
Publication year - 2005
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.2005.tb12206.x
Subject(s) - estrous cycle , luteolysis , zoology , herd , prostaglandin f2alpha , corpus luteum , cloprostenol , estradiol benzoate , pregnancy , dairy cattle , medicine , andrology , endocrinology , biology , prostaglandin , ovary , hormone , ovulation , genetics , ovariectomized rat
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) F 2 aL 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 PGF 2 aL (cloprostenol, 375 mUg, IM) 12 days apart. Heifers not detected in oestrus 48 h after the last dose of PGF 2 aL 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 PGF 2 aL Heifers were inseminated on detection of oestrus. Results After the last dose of PGF 2 aL, oestrous detection rates at 80 h (43.5 vs 72.6%, P < 0.001), 96 h (74.1 vs 84.9%, P=0.025) and 120 h (78.2 vs 86.3%, P=0.082) were less in the No ODB compared to the ODB heifers, respectively. Conception rates (percentage pregnant that were inseminated) were greater in the No ODB compared to the ODB heifers (64.3% vs 47.6%, respectively; P=0.006), while pregnancy rates (percentage pregnant that were treated) were also greater in the No ODB compared to the ODB heifers, but differences were not significant (50.3% vs 41.1%, respectively; P = 0.068). Conclusion Administration of ODB to heifers not in oestrus 48 h after a two‐dose PGF 2 aL treatment increases the percentage of heifers detected in oestrus by 80 h, 96 h and 120 h after treatment, by an estimated 29%, 11% and 8%, respectively. However, administration of ODB decreases conception rates by an estimated 17%, and may decrease pregnancy rates (estimated 9% difference). Results are consistent with the hypothesis that ODB can increase submission rates but reduce conception rates following a two dose treatment with PGF 2 aL.