Original Scientific Article
Modification of the standard 7-day Ovsynch protocol to increase the luteolytic and synchronization risks in dairy cows
Branko Atanasov*,
Nikola Adamov,
Irena Celeska,
Ksenija Ilievska,
Branko Angjelovski,
Zvonko Trbogazov,
Filip Davkov,
Toni Dovenski,
Geert Opsomer,
Jeffrey Stevenson

Mac Vet Rev 2020; 43 (2): 161 - 167


Received: 16 June 2020

Received in revised form: 13 August 2020

Accepted: 28 August 2020

Available Online First: 14 September 2020

Published on: 15 October 2020

Correspondence: Branko Atanasov, batanasov@fvm.ukim.edu.mk


We hypothesized that a single dose of PGF2α belatedly injected on day 8 after GnRH-1 in cows receiving a 7-day Ovsynch-56 protocol (GnRH – 7 days – PGF2α – 56h – GnRH – 16h – timed AI) will increase the proportion of cows with complete luteolysis. At day 35±3 postpartum, 70 lactating Holstein cows from one herd were scored for body condition and pre-synchronized with PGF2α and GnRH (3 days apart) and 7 days later submitted to an Ovsynch-56 protocol for first AI after random assignment to two treatments: (1) OV-7 (n=35) with an injection of PGF2α either on day 7; or (2) OV-8 (n=35) on day 8 after G1, respectively. Blood was collected before the first PGF2α, at day 7 and day 8 in OV-7 and OV-8, respectively, at AI and at 7 days after AI to assess progesterone concentration. Ten cows were classified as acyclic and were excluded from the analysis resulting in 60 cows (OV-8, n=27; OV-7, n=33). In total, more (P=0.01) OV-8 cows and more (P=0.04) primiparous OV-8 cows had complete luteolysis compared with their OV-7 herd mates. In addition, more (P=0.008) OV-8 cows with BCS<2.75 had complete luteolysis compared with their OV-7 herd mates, whereas no difference was observed between treatments among cows with BCS ≥2.75. In conclusion, delaying the application of PGF2α by 1 day reduced the percentage of primiparous cows and cows with poorer BCS having incomplete luteal regression at the time of AI.

Keywords: luteolysis, synchronization risk, Ovsynch, dairy cows, BCS


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© 2020 Atanasov B. This is an open-access article published under the terms of the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Conflict of Interest Statement

The authors have declared that no competing interests exist.

Citation Information

Macedonian Veterinary Review. Volume 43, Issue 2, Pages 161-167, e-ISSN 1857-7415, p-ISSN 1409-7621, DOI: 10.2478/macvetrev-2020-0028, 2020