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A field investigation of a modified intravaginal progesterone releasing device and oestradiol benzoate based ovulation synchronisation protocol designed for fixed-time artificial insemination of Brahman heifers

Edwards, S. A. A. and Boe-Hansen, G. B. and Satake, N. and Chandra, K. and McGowan, M. R. A field investigation of a modified intravaginal progesterone releasing device and oestradiol benzoate based ovulation synchronisation protocol designed for fixed-time artificial insemination of Brahman heifers. Animal Reproduction Science .

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Article Link(s): http://dx.doi.org/10.1016/j.anireprosci.2015.07.01...

Publisher URL: http://www.sciencedirect.com/science/article/pii/S0378432015001785

Abstract

Pregnancy rates (PR) to fixed-time AI (FTAI) in Brahman heifers were compared after treatment with a traditional oestradiol-based protocol (OPO-8) or a modified protocol (OPO-6) where the duration of intravaginal progesterone releasing device (IPRD) was reduced from 8 to 6 days, and the interval from IPRD removal to oestradiol benzoate (ODB) was increased from 24 to 36 h. Rising 2 yo heifers on Farm A: (n = 238 and n = 215; two consecutive days AI); B (n = 271); and C (n = 393) were allocated to OPO-8 or OPO-6. An IPRD was inserted and 1 mg ODB i.m. on Day 0 for OPO-8 heifers and Day 2 for OPO-6 heifers. On Day 8, the IPRD was removed and 500 μg cloprostenol i.m. At 24 h, for OPO-8 heifers, and 36 h, for OPO-6 heifers, post IPRD removal all heifers received 1 mg ODB i.m. FTAI was conducted at 54 and 72 h post IPRD removal for OPO-8 and OPO-6 heifers. At Farm A, OPO-6 heifers, AI on the second day, the PR was 52.4 to FTAI (P = 0.024) compared to 36.8 for OPO-8 heifers. However, no differences were found between OPO-8 and OPO-6 protocols at Farm A (first day of AI) (39.9 vs. 35.7), or Farms B (26.2 vs. 35.4) and C (43.2 vs. 40.3). Presence of a corpus luteum at IPRD insertion affected PR to FTAI (43.9 vs. 28.8; P < 0.001). This study has shown that the modified ovulation synchronisation protocol OPO-6 may be a viable alternative to the OPO-8 protocol for FTAI in B. indicus heifers.

Item Type:Article
Business groups:Animal Science
Keywords:Bos indicus Brahman Progesterone Fixed-time artificial insemination Ovulation synchronization Welfare
Subjects:Science > Biology > Genetics
Science > Biology > Reproduction
Animal culture > Cattle
Deposited On:22 Sep 2015 23:14
Last Modified:22 Sep 2015 23:14

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