Tuyển tập các báo cáo nghiên cứu về bệnh thú y được đăng trên tạp chí y học General Psychiatry cung cấp cho các bạn kiến thức về ngành thú y đề tài: Pregnancy Rates in Repeat-breeder Heifers Following Multiple Artificial Inseminations during Spontaneous Oestrus. | Acta vet. scand. 2005 46 1-12. Pregnancy Rates in Repeat-breeder Heifers Following Multiple Artificial Inseminations during Spontaneous Oestrus By Bhupender Singh Fernando Saravia Renée Bảge Heriberto Rodriguez-Martinez Division of Comparative Reproduction Obstetrics and Udder Health Department of Clinical Sciences Faculty of Veterinary Medicine and Animal Science Swedish University of Agricultural Sciences SLU Centre for Reproductive Biology in Uppsala CRU . Box 7039 SE-750 07 Uppsala Sweden. Singh B Saravia F Bâge R Rodríguez-Martínez H Pregnancy rates in repeatbreeder heifers following multiple artificial inseminations during spontaneous oestrus. Acta vet. scand. 2005 46 1-12 - Hormonal asynchronies during oestrus related to the presence of suprabasal plasma-progesterone P4 concentrations and a delayed ovulation interfere with the fertility of repeat-breeder heifers RBH . Since tubal dysfunction can occur in connection with hormonal asynchronies and constrained availability of fertile spermatozoa at the time of ovulation the present study tested the hypothesis that frequent sperm deposition from onset of oestrus to ovulation may improve pregnancy rates in RBH. Five RBH and five virgin heifers VH controls were repeatedly artificially inseminated AI at 6 h intervals from onset of oestrus to spontaneous ovulation. Hormone analyses revealed suprabasal P4 concentrations and a delay in the occurrence of the luteinising hormone LH surge but a normal cortisol profile in RBH. Compared with controls RBH presented longer interval from onset of oestrus to ovulation and therefore received more AIs. Pregnancy rates in RBH reached control levels 60 NS indicating that the hypothesis might be correct. Pregnancy rates in VH were below the expected range presumably attributed to a deleterious influence of the frequent handling. The study suggests that pregnancy rates can be improved in RBH by frequent AI in relation to spontaneous ovulation. However this practice of repeated .
