Details

Autor(en) / Beteiligte

• Edwards, S.A.A.
• Atkinson, P.C.
• Satake, N.
• Boe-Hansen, G.
• McGowan, M.R.

Titel

Ovarian dynamics in response to two modified intravaginal progesterone releasing device and oestradiol benzoate based ovulation synchronisation protocols designed for use in Brahman heifers

Ist Teil von

• Animal reproduction science, 2014-07, Vol.148 (1-2), p.18-25

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2014

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• The objective was to investigate the ovarian response of Brahman heifers to two modified ovulation synchronisation protocols developed to increase the proportion of normal synchronous ovulations. Experiment 1 characterised the growth of the ovulatory follicle in heifers (n=19) treated with an intravaginal progesterone releasing device (IPRD) and oestradiol benzoate (ODB), to determine the optimal time to induce ovulation. Using the findings from Experiment 1, Experiment 2 investigated the effect of reducing the duration of IPRD insertion and increasing the interval from IPRD removal to ODB treatment (modified protocol 1 – OPO-6; n=20), and omitting ODB treatment at the time of IPRD insertion (modified protocol 2 – PO-6; n=20). An IPRD (0.78g progesterone) was inserted at Day 0 (OPO-8) or Day 2 (OPO-6 and PO-6) and all heifers also received 1mg ODB i.m. Day 8: IPRD removed+500μg cloprostenol i.m. At 24h (OPO-8) and 36h (OPO-6 and PO-6) post IPRD removal: 1mg ODB i.m. Fixed-time AI (FTAI) occurred at 54h for OPO-8 and 72h for OPO-6 and PO-6, post IPRD removal. After IPRD treatment all OPO-6 and OPO-8 heifers initiated a new follicular wave whereas 25% of PO-6 heifers failed. Diameter of the dominant follicle was larger at FTAI in the PO-6 (11.34±0.50mm) compared to the OPO-8 protocol (9.74±0.51mm; P<0.05), but similar to the OPO-6 protocol (10.52±0.51mm). Proportion of ovulations occurring 12h prior and 24h post FTAI was similar for the PO-6 (80%) and OPO-6 (75%) protocols but numerically lower in the OPO-8 heifers (60%). The apparent improvement in ovarian response in heifers treated with the modified protocols needs to be confirmed in larger field studies.