At the moment there are a large number of synchrony programmes being used with varying degrees of success. Three commonly encountered programmes are Ovsynch56, Co-synch48 and Cosynch72 (Figure 1).A direct comparison of these three programmes (Ovsynch56, Cosynch48 and Co-synch72) was undertaken to determine which had the best reproductive outcomes (Brus-veen et al, 2008). The programmes differ in the interval from the prostaglandin injection to timed artificial insemination (TAI), and the timing in relation to the secondgonado-tropin-releasing hormone (GNRH) injection. Pregnancy examination was undertaken on day 31-33 and day 52-54 after TAI. The results of the study showed similar fertility was achieved between Cosynch48 and Cosynch72 cows. Ovsynch56 cows had improvedfertility at both pregnancy examinations when compared with both of the Cosynch protocols, and the authors concluded that there was no advantage to be gained from the two Cosynch protocols, and there was a fertility advantage to be gained from Ovsynch56. The results of this study highlight that by continuing to use Cosynch48 and Cosynch72 protocols in dairy cattle we are applying TAI at a suboptimal point in relation to the prostaglandin and second GNRH injections (Fricke, 2008).
展开▼
