Comparative Study of Pregnancy Rate of Dairy Cows Inseminated with Fresh or Frozen-Thawed Semen

Abstract

The aim of this study was to investigate conception rates (CR) achieved with artificial insemination of Holstein cows using fresh or frozen insemination doses (ID). The synchronization protocols (Double-Ovsynch, Ovsynch, ReSynch) and pedometers were used to secure proper timing of artificial inseminations (AI). Total of 3979 inseminations data were recorded. Statistical analysis was performed using the SAS 9.3 package. For the evaluation of a CR, the effects of ID type, season, year, sire breed, lactation number and oestrus detection type, were analysed. Cows inseminated with fresh ID performed higher CR (+4.86%; P < 0.05). Best pregnancy per artificial insemination (P/AI) success was observed during the winter season (+11.82%; P < 0.01). Parity affected P/AI with primiparous having a greater P/AI than multiparous cows (P < 0.01). The least likelihood of pregnancy success matched up with ReSynch and the highest with Ovsynch protocol (+7.7%; P < 0.05). In conclusion, fresh ID manifested superior CR over frozen-thawed semen under common conditions of Czech dairy farming. Similar or better P/AI was achieved when an automated activity monitoring were used rather than timed AI based on Ovsynch protocol, indicating a possible reduction in hormonal treatment applications without affecting fertility of high producing dairy cows.

Keywords

• dairy cows
• Holstein
• artificial insemination
• cryopreservation
• insemination dose
• frozen-thawed semen