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Abstract Background In Korean cattle, after foot‐and‐mouth disease (FMD) vaccination, anovulation increases, acute immune response is stimulated. Objective Here, we aimed to improve the fertility rate by ovulation delay caused by the foot‐and‐mouth disease vaccine. Methods 160 cows (control, FMD, FMD+Gn250 and FMD+Gn500 groups, with 40 cows each) were used. We analysed the ovulation delay, ovulation rate, conception rate and acute‐phase immune responses. Results In the group vaccinated only with FMD, the average follicle size was maintained at 12 mm and ovulation was delayed. The ovulation rate of the FMD+Gn500 group (500 μg gonadotropin‐releasing hormone (GnRH) injections 3 days after the FMD vaccination) was the highest at 81.8%. The ovulation rate of the FMD+Gn250 group (250 μg GnRH injections 3 days after FMD vaccination) was 54.5%, and that of the control group (not FMD vaccinated) was 53.3%. The conception rate was 52.5% (19/40) in the control group, 37.5% (15/40) in the FMD+Gn250 group, and 67.5% (27/40) in the FMD+Gn500 group. Analysis of acute‐phase immune response revealed that the plasma contents of haptoglobin and serum amyloid A increased up to 7 days after vaccination against FMD in all the experimental groups, except the control group. Conclusions We concluded that ovulation delay can be employed to improve conception rate after FMD vaccination through a modified ovulation synchronisation method with GnRH.

Background: In Korean cattle, after foot‐and‐mouth disease (FMD) vaccination, anovulation increases, acute immune response is stimulated. Objective: Here, we aimed to improve the fertility rate by ovulation delay caused by the foot‐and‐mouth disease vaccine. Methods: 160 cows (control, FMD, FMD+Gn250 and FMD+Gn500 groups, with 40 cows each) were used. We analysed the ovulation delay, ovulation rate, conception rate and acute‐phase immune responses. Results: In the group vaccinated only with FMD, the average follicle size was maintained at 12 mm and ovulation was delayed. The ovulation rate of the FMD+Gn500 group (500 μg gonadotropin‐releasing hormone (GnRH) injections 3 days after the FMD vaccination) was the highest at 81.8%. The ovulation rate of the FMD+Gn250 group (250 μg GnRH injections 3 days after FMD vaccination) was 54.5%, and that of the control group (not FMD vaccinated) was 53.3%. The conception rate was 52.5% (19/40) in the control group, 37.5% (15/40) in the FMD+Gn250 group, and 67.5% (27/40) in the FMD+Gn500 group. Analysis of acute‐phase immune response revealed that the plasma contents of haptoglobin and serum amyloid A increased up to 7 days after vaccination against FMD in all the experimental groups, except the control group. Conclusions: We concluded that ovulation delay can be employed to improve conception rate after FMD vaccination through a modified ovulation synchronisation method with GnRH. [ABSTRACT FROM AUTHOR]

The effectiveness of emergency contraception (EC) is usually estimated by comparing the number of observed pregnancies to that of expected pregnancies after unprotected intercourse. Second-generation selective progesterone receptors modulators have been developed and evaluated for EC use. Among these compounds, ulipristal acetate (UPA) has been proven to share the same antiprogestin activity as mifepristone, and as with mifepristone, UPA has been demonstrated to be effective up to 120 hours after unprotected intercourse. The UPA is more effective than levonorgestrel (LNG) in preventing the appearance of clinically evident pregnancies. The LNG delays ovulation only when taken at the beginning of the fertile period; taken later, it is ineffective on ovulation, while it has been proven to impair the subsequent luteal function. The effectiveness of LNG decreases as time elapses and is limited to 72 hours after unprotected intercourse. The UPA maintains consistent effectiveness for 5 days after unprotected intercourse, and this effectiveness is independent on which of these 5 days it is taken. The ability of UPA to delay ovulation decreases progressively as ovulation approaches and is null at the time of the luteinizing hormone (LH) peak: 1 to 2 days before ovulation, UPA behaves as a placebo. The persistent effectiveness of the drug cannot be due to antiovulatory action, as it decreases sharply as LH approaches its peak level. The effectiveness is most likely due to the dramatic endometrial effects of the drug that are produced regardless of when it is taken. These effects are consistently present, as the threshold for altering endometrial morphology is lower than the threshold for altering folliculogenesis. [ABSTRACT FROM AUTHOR]