Original Scientific Article
Comparative reproductive response of Bulgarian Murrah buffaloes to Ovsynch protocol across breeding and non-breeding seasons
Yordanka Ilieva ,
Ivan Fasulkov * ,
Radena Nenova ,
Pencho Penchev ,
Мanol Karadaev ,
Nasko Vasilev

Mac Vet Rev 2026; 49 (2): i - ix

10.2478/macvetrev-2026-0025

Received: 30 June 2025

Received in revised form: 18 August 2026

Accepted: 10 September 2026

Available Online First: 30 September 2026

Published on: 15 October 2026

Correspondence: Ivan Fasulkov, ivan.fasulkov@trakia-uni.bg
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Abstract

The aim of this study was to evaluate Ovsynch protocol efficiency and the effect of season on conception rates in Bulgarian Murrah buffaloes. The Ovsynch protocol was applied in 32 buffaloes during the breeding period (Group I) and 15 buffaloes during the non-breeding season (Group II). Ultrasound scans were performed on day -10, day 0 and day 10 to detect ovarian structures and on day 35 after fixed-time artificial insemination for early pregnancy diagnosis. Blood samples were collected on the 7th and 17th day for assay of serum progesterone concentrations and detection of ovulation stage. Discharge was observed in 59.4% (19/32) of the buffaloes from the first and 33.3% (5/15) from the second group. Pregnancy was detected in 52.6% (10/19) of the animals during the breeding season and in 40.0% (2/5) during the non-breeding season. Openness of the cervical canal was registered in 53.1% (17/32) of animals from first group and in 20.0% (3/15) from the  second one, whereas pregnancy was detected in 23.5% (4/17) and 33.3%, (1/3) respectively. During the breeding season the ovulation rate was detected in 71.9% (23/32) of the buffaloes after the first GnRH treatment, and in 81.3% (26/32) after the second one. In the second group, percentages were lower-53.3% (8/15) and 66.7% (10/15). On the 35th day, pregnancy was detected in 46.9% (15/32) of the buffaloes during the breeding season and 20.0% (3/15) during non-breeding season. Our results showed that the Ovsynch protocol is efficient for estrus synchronisation and fertilisation in both season. The highest ovulation rates are obtained in buffaloes with CL and follicle ≤10 mm at starting of protocol. Ultrasound determination of ovarian structures before starting the Ovsynch protocol will increase ovulation and pregnancy rates.

Keywords: buffaloes, hormonal treatment, estrous synchronization, reproductive response, breeding season

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©2026 Ilieva Y. 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 declared that they have no financial or non-financial conflict of interest regarding authorship and publication of this article.

Citation Information

Macedonian Veterinary Review. Volume 49, Issue 2, Pages i-ix, e-ISSN 1857-7415, p-ISSN 1409-7621, DOI:  https://doi.org/10.2478/macvetrev-2026-0025

The all content of the Macedonian Veterinary Review, except where otherwise noted, is licensed under a Creative Commons Attribution License.