Laktasyondaki sütçü ineklerde cinsiyeti belirlenmiş sperma kullanımında gebelik başarısını etkileyen faktörler: Retrospektif bir çalışma.

Objectives:The use of sexed semen has become increasingly common in the dairy cattle industry, especially in recent years. Various factors can affect fertility outcomes when using sexed semen in cows. Success rates with sexed semen can be improved by carefully considering these factors, while neglecting them may lead to reduced fertility rates. The objective of this study, was evaluation of a group of cows, uniform in terms of factors known to affect fertility such as lactation number (second lactation), high milk yield (average 51 liters/day), and type of Timed Artificial Insemination (TAI) protocol with sexed semen from one bull, to identify and emphasize the prominent factors affecting pregnancy with the use of sex-sorted semen in lactating dairy cows.   

Methods: The material of the study includes the cows (n=457) were received the same TAI protocol (G6G) and inseminated with sexed semen from a single bull. Data from these cows, including postpartum health, BCS (Body Condition Score), cyclic activity, response to the TAI protocol, estrus detection rate and follicle size at TAI, pregnancy/AI, and pregnancy loss rates, were evaluated, retrospectively. Mann-Whitney U and Chi-square tests were used to compare continuous and categorical data, respectively. Factors affecting pregnancy/AI were analyzed by logistic regression analysis.

Results: No effect was determined for the parameters related to the physiological condition of the cow such as BCS (p=0.160) and milk yield (p=0.103) on pregnancy success. Likewise, no effect was determined for parameters related to cyclic activity, such as showing signs of estrus during the voluntary waiting period (p=0.279), cyclic activity at the beginning of presynchronization (p=0.637), follicle size (p=0.713), and estrus detection rate at TAI (p=0.160). It was observed that being cyclic at the start of TAI protocol (p=0.089) tends to increase the chance of pregnancy/AI, and responding to the first GnRH application of the protocol (p=0.036) significantly increases the chance of pregnancy/AI. Moreover, cows without a history of retentio secundinarum/metritis in the postpartum period had a 1.5 times higher pregnancy success rate compared to those with such a history (OR = 1.53; 95% CI 1.01-2.32; P=0.046).

Conclusions: It has been confirmed that the cyclic activity status at the beginning of the protocol affect fertility in lactating dairy cows, and the response to the TAI protocol also influence pregnancy success following insemination with sex-sorted semen in these cows. However, no effect was identified regarding the reproductive physiological activities of the animals, such as cyclic activity and showing signs of estrus. Nonetheless, when using sexed semen in lactating dairy cows, it is need to be considered that pregnancy success may be lower in cows that have experienced uterus-related problems during the postpartum period.