Using of SEX sorted semen in lactating DAİRY COWS

The aim of this study was to determine the effect of insemination with sex sorted semen at different times on pregnancy rates in dairy cows that underwent synchronization protocol. For this purpose, second lactation Holstein cows (n=611), which were taken into pre-synchronization protocol (G7G;PGF2α-2d-GnRH-7d-GnRH-7d- PGF2α -56h-GnRH) for the first insemination on postpartum 43-49. days and all cows were randomly divided into 4 groups before insemination. In KON group, cows were inseminated 12.0 to 16.0 h after the last GnRH administration in synchronization protocol with conventional semen. After the last GnRH administration in synchronization protocol; cows were inseminated 12.0 to 16.0 h in CBS group (n=152), 16.1 to 20.0 h in CBS4 group (n=153), 20.1 to 24.0 h in CBS8 group (n=152) with sexed semen. Semen from the same bull was used in all inseminations. All cows were ultrasonographically examined at critical points (beginning of the protocol, insemination time, ovulation control etc.) throughout the study to individually assess the ovarian responses to the protocol. First pregnancy detection was performed around 36 days and second pregnancy detection was performed around 73 days after insemination. There was no statistical difference between the groups in terms of body condition score, milk yields, cyclicity at the beginning of the protocol, response rates to the protocol and follicle size on the day of insemination. Conception rates were detected 50.0 % (77/154) in KON group with conventional semen, 42.8% (65/152) in CBS, 48.4% (74/153) in CBS4 and 43.4% in CBS8 (66/152) with sexed semen. Embryonic loss rates were determined as 5.2% in KON, 9.2% in CBS, 4.1% in CBS4 and 13.6% in CBS8. As a conclusion, in case of using sex sorted semen in synchronization protocols in dairy cows, delaying insemination time by 4 hours and performing insemination 16-20 hours after the last GnRH administration in synchronization protocol resulted with numerically better pregnancy rates and almost achieved similar pregnancy rates with conventional semen.