| Historical Background | Ovsynch Protocol and Function of Each Injection | Ovsynch Conclusions and Discussion |
| Supplies Necessary | Links | Bibliography |
Historically, poor estrus detection and poor conception rates have resulted in huge challenges in managing reproduction in most lactating dairy cow herds. In an effort to assist producers in managing reproduction in a more effective manner, synchronization protocols have been developed with the use of PGF2α. This includes efforts to create timed artificial insemination protocols to assist in estrus detection (Stevenson et. al., 1989). In the past, synchronization protocols have been effective with PGF2α when animals are bred to detected estrus (Archibald et. al., 1992; Lucy et. al., 1986). Using PGF2α allows producers to increase detection of estrus and artifiical insemination management. One important limitation of these protocols has been the fact that estrus has not completely been synchronized, with animals coming into estrus over a period of several days (Lauderdale et. al., 1974).
In addition, it is important to note that conception rates are drastically reduced when cows subjected to a simple PGF2α protocol are bred to timed artificial insemination compared to breeding to a detected estrus (Archibald et. al., 1992; Lucy et. al., 1986; Stevenson et. al., 1987). Thus, a general consensus existed that after much research, there is still a necessity for a synchronization protocol that more precisely synchronizes estrus with a timed artificial insemination that allow for a reliable conception rate.
In 1995, Pursley et. al., tested a new synchronization regimen using gonadotropin releasing hormone (GnRH) and PGF2α (used in the prior studies above). To initiate the protocol, a 100µg intramuscular injection of GnRH is administered at a random stage in the estrus cycle. This intent of this injection is to cause ovulation of a dominant follicle (and thus begin a new follicular wave) or be injected when a new follicular wave is already forming spontaneously (therefore causing the injection to essentially not affect the stage of the estrous cycle). Seven days later, a 35 mg intramuscular injection of PGF2α is administered to regress any corpus lutea present. The seven day interval is used so that is in fact the initial GnRH injection ovulated a follicle, then the corpus luteum would have grown to a sufficient size to be responsive to PGF2α. 48 hours later, the cows receive another 100µg intramuscular injection of GnRH to ovulate the new dominant follicle. The nine days allowed between the two injections of GnRH is designed to be sufficient for a new follicle to emerge and grow to an appropriate size to response to the GnRH. Finally, 24 hours later the cows are bred via artifial insemination. A sample protocol is shown below in Table 1. Please note that although the specific day of the week is not important, the interval between the injections is very critical to the synchronization protocol.
Reproductive efficiency is dependent upon both service rate and conception rate. The Ovsynch protocol described above has many benefits, including the following:
As stated above, Ovsynch allows the Artificial Insemination Technician to breed many cows at one visit to the farm, thus there are a great number of supplies that are needed. For each cow that is synchronized using the above protocol, the following supplies are needed:
In addition, the typical artificial insemination supplies are also necessary, which include the following:
Shown below are links to examples of products that can be used in the Ovsynch protocol.
Archibald L F, Tran T, Massey R, and Klapstein E. Conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotropin-releasing hormone and/or prostaglandin F2o. Theriogenology 1992; 37:723.
Lauderdale J W, Seguin B E, Stellflug J N, Chenault J R, Thatcher W W, Vincent C K, and Loyancano A F. Fertility of cattle following PGF2o injection. J Anim Sci 1974; 38:964-967.
Lucy M C, Stevenson J S, and Call E P. Controlling first service and calving interval by prostaglandin F2o gonadotropin-releasing hormone and timed insemination. J Dairy Sci 1986; 69:2186.
Pursley J R, Kosorok M R, and Wiltbank M C. Reproductive management of lactating dairy cows using synchronization of ovulation. J Dairy Sci 1997; 80:301-306.
Pursley J R, Mee M O, and Wiltbank M C. Synchronization of ovulation in dairy cows using PGF2α and GnRH. Theriogenology 1995; 44:915-923.
Stevenson J S, Lucy M C, and Call E P. Failure of timed inseminations and associated luteal function in dairy cattle after two injections of prostaglandin Fza Theriogenology 1987; 28:937.
Stevenson J S, Mee M 0, and Stewart R E. Conception rates and calving intervals after prostaglandin F2o or prebreeding progesterone in dairy cows. J Dairy Sci 1989; 72:208-2 18.
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