文摘
The effects of different artificial insemination (AI) techniques and sperm doses on pregnancy rates of normal Hanoverian breed mares and mares with a history of barrenness or pregnancy failure using fresh or frozen–thawed sperm were investigated. The material included 187 normal mares (148 foaling and 39 young maiden mares) and 85 problem mares with abnormal reproductive history. Mares were randomly allotted into groups with respect to AI technique (routine AI into the uterine body, transrectally controlled deep intracornual AI ipsilateral to the preovulatory follicle, or hysteroscopic AI onto the uterotubal junction ipsilateral to the preovulatory follicle), storage method of semen (fresh, frozen–thawed), AI volume (0.5, 2, 12ml), and sperm dose (50×106 or 300×106 progressively motile sperm (pms) for fresh semen and 100 or 800×106 frozen–thawed sperm with >35 % post-thaw motility). The mares were inseminated once per cycle, 24h after hCG administration when fresh semen was used, or 30h for frozen–thawed semen. Differences in pregnancy rates between treatment groups were analyzed by Chi-squared test, and for most relevant factors (insemination technique, mare, semen, and stallion) expectation values and confidence intervals were calculated using multivariate logistic models.