Selective use of a modified pre‐synchronization‐Ovsynch and resynchronization reproductive strategy in dairy herds: A field application study

The reproductive efficiency of the cows was monitored after two resynchronization protocols: Ovsynch (OVS) and Double Ovsynch (DOS). The research initially included 70 HF cows who entered the first synchronization protocol – Presynch. Cows that did not conceive after the first synchronization were divided into two groups and introduced to two resynchronization protocols. In the first group of cows (n=35), the DOS protocol began with the application of GnRH on day 22 after the Presynch TAI (Timed Artificial Insemination), and seven days later pregnancy check-up was done and PGF2α was applied only to non-pregnant cows (n=23), which remained in the study. In the second group of cows, the OVS protocol started on day 32 after Presynch TAI only in non-pregnant animals (n=20). Progesterone (P4) concentration was determined at the time of application of GnRH1, PGF2α and GnRH2 in both groups of cows, and then 30 days after Resynch TAI, ultrasound pregnancy diagnosis was done. A higher percentage of pregnant cows were recorded in the OVS group compared to the DOS group (45% and 35%, respectively). The concentration of P4 in the serum of cows in the DOS group during the first measurement (GnRH1) was significantly higher than the value in cows that did not conceive (p<0.05), while in the third measurement (GnRH2) the average concentration of P4 in conceiving cows was significantly lower (p<0.001) compared to cows that did not coincive. The open days period was significantly longer in pregnant cows that were resynchronized using the DOS protocol compared to cows from the OVS protocol. In conclusion, the OVS protocol of estrus resynchronization in dairy cows proved to be more successful than the DOS protocol. However, considering the advantages the OVS, it is needed to determine which day of the sexual cycle is the best to start resynchronization.

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Efficiency of Two Protocols of Resynchronization of Estrus and Ovulation in High-Producing Dairy Cows at Peak Lactation

Đorđević¹,

Blagojević

Radinović

et al. 2022

Acta Veterinaria

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Association of FSHR gene polymorphism with fertility of Holstein cows

Turlova,

Pozovnikova,

Krutikova

et al. 2024

Agrarnaâ nauka

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Relevance. The view of the mechanisms of hormonal regulation of the ovarian cycle of cows has allowed the development of a large number of synchronization programs. An active search is underway for biomarkers related to the fertility of cows, as well as to identify animals with a high ovarian response to the injection of exogenous gonadotropins. The aim of the work is to study the polymorphism of the FSHR gene and its association with reproduction indicators in black-and-white Holstein dairy cows.Results. Based on the results of genotyping cows (n = 128) using the FSHR gene, the frequency of occurrence of the CC genotype was determined at the level of 0.601, the CG genotype — 0.360, GG — 0.031. It was found that for productive insemination, animals with the CG genotype require fewer inseminations. At the same age, the frequency of insemination of heifers with the CG genotype was 1.43, with the CC genotype — 1.60. After the first calving, the animals with the CG genotype responded more actively to hormonal stimulation in the postpartum period. The interval from the first to fruitful insemination in cows with the CG genotype was 34.7 days, in cows with the CC genotype — 57.2 days (p < 0.05). The number of pregnant cows with the CG genotype re-inseminated after natural hunting was 2.1 times higher than the number of cows with the CC genotype (66.7% and 31.2%). It is assumed that exogenous hormone injection has a stimulating effect on the hypothalamus-pituitary-gonad system in cows with the CG genotype.

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Selective use of a modified pre‐synchronization‐Ovsynch and resynchronization reproductive strategy in dairy herds: A field application study

Cited by 2 publications

References 60 publications

Efficiency of Two Protocols of Resynchronization of Estrus and Ovulation in High-Producing Dairy Cows at Peak Lactation

Efficiency of Two Protocols of Resynchronization of Estrus and Ovulation in High-Producing Dairy Cows at Peak Lactation

Association of FSHR gene polymorphism with fertility of Holstein cows

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