Detection and treatment of repeat breeder cows with altered epidermal growth factor expression in the uterus

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This project aimed to develop diagnostic method and treatment of repeat breeder cows with uterine dysfunction as a cause of infertility. First the profile of epidermal growth factor (EGF) in the endometrium was determined. EGF showed two peaks during the estrus cycles, Days 2-4 and 13-14. About 70% of repeat breeder cows showed abnormality in the EGF profile, typically lack of these peaks. This abnormality persisted between the estrous cycles and normalization of EGF profile resulted in restoration of fertility, indicating that the abnormal EGF profile may be a part of causes of infertility in dairy cattle. Then, treatment to the abnormality has been developed. When a high dose of estradiol-benzoate (EB, 5 mg) was given in combination of a CIDR device, the EGF profile was normalized in about 70% and 70-80% of them became pregnant after treatment. Then, the EGF profile was determined in recipient cattle for embryo transfer (ET) to assess if the endometrial EGF profile may serve as an indicator of fertility in cattle. Cows with a normal EGF profile showed higher pregnancy rate after ET compared with those with an abnormal EGF profile (70 vs. 30%), indicating the EGF profile can be an indicator of fertility and, thus, become a useful marker of recipient selection in ET program. Finally, factors which may affect the recovery of the EGF profile after parturition was examined. Luteal phase of at least for 8 days may be required for the recovery of cyclicity in the endometrial EGF profile. However, appearance of a luteal phase (> 11 days) before uterine involution and repeated short (< 8 days) luteal phases seemed a risk factor to increase the frequency of a abnormal EGF profile at the time of insemination.