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    Effects of Heat-Stress on Oocyte Number and Quality and In Vitro Embryo Production in Holstein Heifers
    (Univ Fed Rio Grande Do Sul, 2022) Cizmeci, Sakine Ulkum; Dinc, Dursun Ali; Yesilkaya, Omer Faruk; Ciftci, Muhammed Furkan; Takci, Abdurrahman; Bucak, Mustafa Numan
    Background: This study aimed to determine the effects of environmental temperature on the number and quality of oocytes and embryo production rates obtained by performing ovum pick up (OPU). Heat stress leads to long-term, short-term, visible, and invisible effects in dairy cows. Its effects on reproduction are evident in all stages, from oocyte development to birth. Disturbance in ovarian follicle development, follicular dominance deficiency, anoestrus, polyspermia, embryonic losses, decreased fetal growth, and abortion are some examples of responses to these effects. The aim of the present study was aimed to determine the effects of ambient temperature on oocyte quality and number and embryo production rates. Materials, Methods & Results: The animal material used in this study comprised 10 Holstein heifers. At the beginning of the study, the heifers were 13-15 months old. OPU was performed at different times of the year, and weather conditions were recorded. Grouping according to ambient temperature was done as < 10 degrees C (group 1), 10-25 degrees C (group 2), and > 25 degrees C (group 3). The veterinary ultrasonography device and a set of compatible intravaginal OPU probe, catheter, and aspiration device were used for OPU application. All antral follicles with diameters of 2-8 mm in the ovaries were aspirated. The aspirated follicle fluids were examined under a stereo microscope, and the cumulus-oocyte complexes (COC) were collected and classified according to their structure. A, B, and C-quality oocytes were included in the in vitro embryo production process. After performing 69 OPUs on random days of the cycle, the number of oocytes per OPU was found to be 8.72, 6.32, and 6.85 in groups 1, 2, and 3, respectively (P < 0.05). The number of viable oocytes per OPU was 6.83, 4.64, and 4.65 in groups 1, 2, and 3, respectively (P < 0.05). The statistical difference between the first group and the other groups was significant for cleavage and blastocyst counts (P < 0.05). Discussion: All the negative effects of heat stress on animals resulted from the increased body temperature. Reproductive performance is adversely affected by high temperatures and humidity during periods of high ambient temperatures. Metabolic heat is released, and the heat load increases due to the metabolism of nutrients in cattle. Internal body temperature is regulated via the dissipation of metabolic heat to the environment. The amount of heat dissipated via conduction and convection depends on the unit body weight, surface area, skin and coat color, difference in temperature gradient of the animal and ambient temperature, and humidity. In the present study, it was determined that the blastocyst development rates of the oocytes obtained in the warm season (>25 degrees C [group 3]) were lower than those of the other groups. It was concluded that this may be because the oocytes developed under chronic heat stress in the animals, and several cycles were required to enhance oocyte quality and developmental potential. Additional studies are needed to investigate the response of oocytes obtained with OPU to heat stress during embryonic developmental stages and to determine the sensitivity and effects of embryonic tissue damage according to developmental stages. Based on the results of the present study, it was concluded that performing OPU and in vitro embryo production (IVEP) when the ambient temperature is close to the thermoneutral limits may increase the blastocyst development rates.
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    Evaluation of hormonal protocols for induction of synchronized estrus on reproductive indices in Kangal-Akkaraman ewes during the outbreeding season
    (Elsevier, 2022) Cizmeci, Sakine Ulkum; Kivrak, Mehmet Bugra; Takci, Abdurrahman; Dinc, Dursun Ali; Coskun, Behic
    The objective of this study was to assess the effect of human chorionic gonadotropin (hCG) and gonadotropinreleasing hormone (GnRH) treatment before sponge insertion and anti-Mullerian hormone (AMH) concentration in ewes which were either pregnant or non-pregnant during the previous breeding season. In the study, 375 (3-6-year-old) Kangal-Akkaraman ewes that conceived or did not conceive in the preceding breeding season, and 36 rams (3-6-year-old) were used. The sheep were randomly divided into 5 equal groups. Blood samples were taken before stimulation (day 4), the day stimulation was initiated (day 0), after stimulation (day 9), on the mating day (days 11-12). AMH concentrations were measured in the samples taken on 4th day. As a conventional method, a sponge containing 20 mg of flugeston acetate (Chronogest (R) CR, MSD, Turkey) was placed intravaginally (day 0) into to study ewes. The ewes were intramuscularly administered 131.5 mu g prostaglandin F2 alpha (Estrumate, MSD, Turkey) and 600 IU equine chorionic gonadotropin (Chronogest (R) PMSG 6000, MSD, Turkey) simultaneously with sponge removal 9 days after insertion. No other treatment was applied to group 5 which served as control. Ewes in groups 1, 2, and 3 received an intramuscular injection of GnRH (4.2 mu g of Buserelin acetate, Receptal, MSD, Turkey) at the time of insertion of progesterone sponge. GnRH or 600 IU hCG (Chorulon (R), MSD, UK) was administered 4 days prior to sponge insertion for the ewes in the groups 2, and 3, respectively. As for the group 5 group, hCG (instead of GnRH) was administered to the ewes at the beginning of the progesterone treatment. Ewes in estrus were detected with a teaser ram and taken into a different pen with rams. Transrectal ultrasonography (Mindray DP50/Vet/US, rectal probe) was achieved during days the 30-35 following mating. Transabdominal ultrasonography was achieved during days 60-65 to detect late embryonic and early fetal death. The estrus rate was 71.19 % out of breeding season for all ewes. The pregnancy rate on day 30 post-mating was 32 % in the control group and was 31.00 %. No significant differences were observed between groups for pregnancy rates on day 30. The mean pregnancy rate in sheep that conceived and did not conceived in the preceding breeding season of the study was 32.03 % and 32.06 % respectively (P > 0.05). After treatments, AMH concentrations in non-pregnant were significantly higher than pregnant ewes (P < 0.005). In conclusion, although the AMH concentration is significantly higher in non-pregnant ewes, the AMH concentration may not be a suitable biomarker to predict induction success outside breeding season. Progesterone-based protocols may achieve an acceptable reproductive outcome in lactating ewes and the ones which experienced infertility.
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    Interaction of cumulus-oocyte complex (coc) number, oocyte quality, and blastocyst numbers by repeated ovum pick-up (opu) in in vitro embryo production
    (Chulalongkorn University Printing House, 2024) Cizmeci, Sakine Ulkum; Dinc, Dursun Ali; Bucak, Mustafa Numan; Yesi̇Lkaya, Omer Faruk; Ciftci, Muhammed Furkan; Kivrak, Mehmet Bugra; Sari, Ayse
    Ovum pick-up (OPU) is a repeatable technique that is used for the retrieval of large numbers of immature oocytes from the antral follicles of live animals. The aim of the present study was to determine the effect of repeated OPU application on cumulus-oocyte complex (COC) number, oocyte quality, and blastocyst rates. The animal material for the study consisted of 10 Holstein heifers. Heifers selected as donors were administered OPU a total of 9 times on random days of the cycle at 1-week intervals. All antral follicles with a diameter of 2-8 mm were aspirated during the OPU procedure. In vitro embryo production (IVEP) was performed on the oocytes obtained after quality assessment. Various degrees of adhesion and connective tissue thickening were found in the ovaries of the animals after 9 repeated applications of OPU. It was found that the average number of A-quality oocytes was higher than the number of B, C, and D-quality oocytes. The number of cleavages per OPU was 2.69 (cleaved oocytes/opu session), and the number of blastocysts was 0.72 (number of blastocysts/opu session). It was determined that the general average of cleavage ratios was 73.62%, and blastocyst rates were 18.97%. It was observed that the number of oocytes, cleavage, and blastocysts obtained as a result of repeated OPU applications was not affected by repeated OPU. It was concluded that in order to achieve the target number of oocytes and blastocysts with recurrent OPU, experiments should be carried out with varying frequencies of OPU, and prophylactic measures should be taken to prevent adhesions. © 2024 Chulalongkorn University Printing House. All rights reserved.