Two experiments were designed to study the effect of semen extenders and freezing regimens on post-thaw semen motility and viability index, effect of bucks breed was also included (experiment 1). In experiment 2, semen diluents effects on reproductive performance was conducted. Semen was collected from bucks breeds (Aradi (A), Damascuss (D) and cross (½A½D). Good quality semen was divided into 4 portions, each diluted with one diluent (Milk, Na.Citrate, Tris and Na.Bicarbonate). The diluted semen was packaged into 0.5ml straws then cooled to 5°C. After equilibration, half of the packaged straws were suspended 15cm above liquid nitrogen (LN) for 15min (Freezing regimen1; slow). Other half of straws was suspended at height 15 and 5cm of LN for 10 and 5min, respectively (Freezing regimen2; rapid) before plunged into LN. Frozen semen was thawed for post-thaw motility and viability. In the second experiment, semen with good quality was extended with three types of extenders (Milk, Na.Citrate and Tris). Diluted semen were cooled to 5°C and used for AI. Results revealed that, pre-freeze semen motility was significant higher in Tris, Na.Citrate and Na.Bicarbonate than milk diluent. Post-thaw semen motility and viability were highly significant for milk and Na.Citrate than Tris and Na.Bicarbonate diluents. Post-thaw semen motility was significantly higher in Aradi and Damascus than cross breed. Post-thaw semen motility and viability revealed, significant higher means for Freezing regimen 2 than regimen 1. Milk was significantly higher than Tris and Na.Citrate diluents for fertility and fecundity. It was concluded that, regarding to post-thaw semen viability, fertility%, kidding%, fecundity% and prolificacy%, milk is preferable than Tris and Na.citrate diluents.
The study aimed to determine the influence of estrus synchronization regimes on reproductive performance in Barki ewes. Forty Barki ewes were randomly allocated into 2 equal groups (A & B). Group A were treated with vaginal sponges impregnated with 25 mg medroxy-progesterone acetate (MAP). On the day of sponge's withdrawal the ewes were reassigned according to eCG dose into three subgroups (A1, A2 and A3). Group A1, served as control, without eCG injection, while groups A2 and A3 were injected IM with 300 and 500 IU/eCG, respectively. The ewes of group B have received vaginal sponge containing 50 mg of MAP. At the day of sponge removal, the ewes were subdivided into 3 subgroups B1, B2 and B3 and treated with eCG as subgroups A1, A2 and A3, respectively. Three fertile rams were subjected to run with ewes for heat detection and natural mating. Blood samples were taken from mated ewes on day 17 post mating, for determination the level of progesterone for pregnancy determination. Results revealed that the incidence of estrus response were 74.60±9.71 and 79.37±9.71 for groups A (25 mg MAP) and B (50 mg MAP), respectively. Irrespective to MAP sponge concentrations, the estrus response in ewes injected with 500 IU/eCG (A3B3) was higher (92.86±11.58%) than group A2B2 (71.43±11.58%) which treated with 300 IU/eCG and control group A1B1 without eCG (66.67±12.51%) with no significant differences. The onset of estrus in ewes of group A was significantly shorter (P<0.05) than group B (36.23±3.18 h vs 46.10±3.41 h). Regardless of MAP, the onset of estrus in control ewes (without eCG) was significantly longer (56.02±4.70 h; P<0.01) than ewes treated with 300 IU/eCG, (36.20±3.82 h) and 500 IU/eCG (31.27±3.49 h). The means of estrus duration were similar with no significant effects of MAP and eCG doses. No significant differences in the pregnancy rates between group A and B, whereas, the pregnancy rate was significantly higher in group A3B3 (92.86±11.21%) than groups A1B1 and A2B2 (50.00±14.24 and 80.00±12.74%, respectively). Neither MAP nor eCG has been a significant effects on the lambing and fecundity rates. In conclusion, Sponges containing 25mg MAP co-treated with 300-500 IU/eCG is suitable protocol for estrus synchronization and improve pregnancy rate in Barki ewes.
The current study aimed to characterize the plateau patterns of plasma progesterone in the peripheral circulation during the application of vaginal sponge impregnated with different concentrations of medroxyprogesterone acetate (MAP) and co-treated without and with different doses of equine chorionic gonadotropin (eCG) and its effects on some items of reproductive performance. Determination the onset surges (time and level) of LH and estradiol-17β were also aimed in the study as a necessary pinpoint to the time of ovulation after MAP sponge-eCG treatment. Forty Barki ewes were randomly allocated into 2 main groups (A & B) of equal numbers (n=20/group). Groups A and B were treated with vaginal sponges containing 25 and 50 mg MAP, respectively. On day of sponge's withdrawal, ewes of each main group were randomly reassigned according to eCG dose into three subgroups (1, 2 and 3). Groups A1 and B1 (n=6 each group), served as control, without eCG injection, while groups A2 and B2 (n=7/subgroup) were injected at sponge removal with 300 IU/eCG, whereas, groups A3 and B3 (n=7/subgroup) were injected with 500 IU/eCG. Blood samples were taken immediately before sponge insertion and after the placement subsequently every 2 days and continued to the end of sponge application to studying the plateau pattern of progesterone in the peripheral circulation. Nine hours after sponge removal to 74h latter, blood samples were also taken every 3h and 6h for determination LH and estradiol-17β surges, respectively. The time to onset estrus (h), estrus duration, pregnancy and lambing rates (%) were recorded as reproductive performance measuring related to the study. The started level of plasma progesterone in group A increased gradually with level reaching to its maximum level on days 6 and 8 of sponge application and then rapidly decreases reaching to minimum level on day of sponge removal. On contrast, the patterns of plasma progesterone changes in group B were forcefully increased but with slightly high level from the beginning reaching its highest concentration on day 6 and day 8, then decline gradually to reach lower level on the day of sponge withdraw. The mean time from sponge withdraw to LH and estradiol-17β surges were significantly shorter (P<0.05) in-group A than B and significantly longer (P<0.01) in group A1B1 than other eCG treated groups. Neither MAP nor eCG have significant effects on LH concentration, while, eCG have positive effects on the concentration of estradiol-17β. Generally, the hormonal plateau patterns of group A were associated with acceleration the time to onset estrus with high pregnancy rate. In conclusion, the protocols used for estrus synchronization in sheep are associated with different plateau patterns of circulating reproductive hormones and subsequently affect reproductive performance.
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