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Title: Sincronizzazione dell’ovulazione della bovina da latte
Other Titles: Synchronization of ovulation in dairy cattle
Authors: Piacentini, Marco
Issue Date: 15-Oct-2020
Publisher: Università degli studi di Parma. Dipartimento di Scienze Medico-Veterinarie
Document Type: Master thesis
Abstract: Reproductive efficiency is an aspect that plays a fundamental role in determining the profitability of the dairy farm. In farms where artificial insemination is practiced, the correct identification of estrus is a key point to obtain good reproductive efficiency. However, the identification of this event is not always easy, since several factors intervene in reducing the ability of the animal to act the characteristic behaviors (Diskin, Sreenan, 2000). To solve and overcome the limitations associated with the visualization of estrus, to be able to increase the number of fertilized cows and to be able to manage more efficiently the reproductive sector of the dairy cow farm, hormonal synchronization protocols have been developed, which allows to practice Timed Artificial Insemination (TAI). The first effective synchronization protocol was devised by Pursley, et al. in 1995 and was called Ovsynch. This protocol involves the alternating use of hormones such as Gonadotropin-Releasing Hormone and Prostaglandins at specific intervals. These hormonal treatments are administered to manipulate the estrous cycle and determine ovulation after an interval of time from the last injection of hormones and to perform a Timed Artificial Insemination that does not require the detection of estrous. However, Ovsynch, if started at a random stage of the estrus cycle, is unable to provide better results than artificial insemination performed after estrus detection. These results are not very satisfactory due to insufficient ovulatory response to the first GnRH treatment in 50% of the cows. This is associated with a reduction in the number of properly synchronized cows at the time of Timed Artificial Insemination (Carvalho, et al., 2018). For this reason, pre-synchronization protocols have been studied and developed that allows maximizing the response to Ovsynch hormone treatments, ensuring better synchronization and a conception rate that varies between 40 and 55% of the animals enrolled in the program (Moreira, et al., 2001, Souza, et al., 2008, Bello, et al., 2006). 2 Although a large part of the herd becomes pregnant at the first insemination post-partum, a considerable portion of animals has to be re-inseminated (Fricke, 2006). Second and subsequent inseminations have the aim of limiting the interval between calving and conception as much as possible so as not to excessively prolong the length of lactation. The use of resynchronization protocols allows reducing the interval between two inseminations in animals that have difficulty manifesting estrus (Sterry, et al., 2006). Furthermore, through the use of protocols that are based on the ovarian structures present at the time of pregnancy diagnosis, it is possible to maximize the fertility of the cows to be re-inseminated (Wijma, et al., 2017).
Appears in Collections:Scienze medico-veterinarie

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