Evaluation of Factors Affecting Pregnancy Rate after Cervical Insemination of Dairy Ewes in Greece

Abstract

The objective of this study was to assess the factors affecting success of cervical Artificial Insemination (AI) with chilled semen in intensively reared dairy ewes in Greece. The study involved 1,785 adult ewes from 20 flocks of Lacaune and Chios sheep. A typical estrous synchronization protocol, including intravaginal placement of progestogen sponge for 14 days and injection of equine chorionic gonadotropin at sponge removal, was applied in ewes during mating period. All ewes were cervically inseminated 53-57 hours after sponge removal with chilled semen (15oC) collected from 10 adult purebred Lacaune rams. Pregnancy Diagnosis (PD) was performed by trans-dermal ultrasonography at 35-38 d after AI. The following data were available for each ewe: breed; parity; Body Condition Score (BCS) at sponge placement, at AI and at PD; presence of rams during synchronization and number of previous synchronizations. Recordings during the AI procedure included: onset of synchronization to AI interval; semen collection to AI interval; semen deposition depth; cervical mucus presence; order of ewe; average time required for each animal; ram semen used. The results showed that farm, parity, semen deposition depth, ram, ewe BCS and changes of BCS during the sponge placement-PD period, significantly affected AI success (P<0.05). Overall fertility was 44%. Ewes of 2nd (50.3%) and 3rd lactation (48.1%) had the highest conception rates, that declined as age increased. Ewes in moderate BCS (2.50-3.50) at onset of synchronization (48.4%) and AI (49.4%) had significantly higher fertility than ewes with low (<2.50) or high (>3.50) BCS. Positive energy balance following the onset of synchronization seems to benefit animals with low and moderate BCS, but decrease pregnancy rates of high BCS ewes. In conclusion, selection of appropriate ewes and rams, BCS evaluation prior to synchronization and adjustment of dietary management are key factors dictating pregnancy rates following AI in greek dairy sheep.

Effect of two animal protein-free extenders on cryopreservation of Pelibuey and Blackbelly ram semen

“…(31,32) On the other hand, the in vivo test depends largely on the fertility of the female, which is affected by a wide range of factors, such as farm, year, season, artificial insemination technique, and technician, (33) heat stress, (34)(35)(36) diet, (37) health status, as well as parity, lambing interval, body condition score, genetic traits, full functionality of reproductive organs, herd management, female prolificacy, nutritional management before and after artificial insemination, the type of estrus (natural or hormonally manipulated), and the site of deposition of the semen and climate factors. (38,39) On the other hand, the sperm parameters evaluated in this study were selected due to their predictive capacity in fertility. For instance, several studies have indicated that sperm viability (live/dead) is related to sheep fertility (40) and bull fertility (41)(42)(43)(44) after artificial insemination.…”