Person: TOKER, MEHMED BERK
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TOKER
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MEHMED BERK
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Publication Ovarian follicle dynamics and hormonal changes during early pregnancy in saanen goats(Czech Academy Agricultural Sciences, 2020-01-01) Doğan, İbrahim; Toker, Mehmed Berk; Alcay, Selim; Küçükşen, Duygu Udum; DOĞAN, İBRAHİM; TOKER, MEHMED BERK; ALÇAY, SELİM; UDUM, DUYGU; 0000-0003-1976-1814; 0000-0003-4033-9749; A-2794-2014; R-8366-2018; CBC-7350-2022; FGX-3813-2022This study is aimed at describing the ovarian follicular dynamics, corpora lutea and their hormonal control during early pregnancy in Saanen goats. The ovaries of pregnant goats (n = 10) were monitored daily for follicles (>= 2 mm) and corpora lutea by transrectal ultrasound over the 35 days after mating. Blood samples were collected by jugular venipuncture at the time of ultrasonography and were analysed for the concentrations of oestradiol (E-2) and progesterone (P-4), inhibin, FSH (follicle-stimulating hormone) and LH (luteinizing hormone). The pattern of follicular growth was characterised by five (n = 2; 20 %), six (n = 5; 50 %) and seven (n = 3; 30 %) follicular waves during early pregnancy. The first corpora lutea (size 6.8 +/- 0.4 mm, mean + SEM) were detected at 5.0 +/- 0.3 days after the mating with a maximum diameter (12.2 +/- 0.3 mm) observed on day 24.0 +/- 1.1 of pregnancy. The dominant follicle diameter of waves 1 and 4, and the duration of waves 1-4 and 7 were maximal during the early pregnancy period (P < 0.05). In addition, the inter-wave interval of the 5 waves was significantly (P < 0.05) longer compared to the six and seven inter-wave intervals (7.0 +/- 0.1, 5.8 +/- 0.1 and 5.0 +/- 0.2 days, respectively). Although the number of small and medium-sized follicles did not differ with the days post-breeding, the number of large-sized follicles in the same period significantly decreased between 16 and 26 days and was negatively correlated with the period of pregnancy (P < 0.05). The plasma LH and E-2 concentrations were negatively correlated with the P-4 concentration. The inhibin concentrations were negatively correlated with FSH, but positively correlated with the number of large-sized follicles. These results indicate that ovarian follicular growth during the first 35 days of pregnancy in goats was characterised by a wave-like pattern and there was a close relationship between the number of FSH peaks and the number of follicular waves.Publication Drone semen cryopreservation with protein supplemented tl-hepes based extender(Kafkas Univ, Veteriner Fakultesi Dergisi, 2019-07-01) Alcay, Selim; ALÇAY, SELİM; Çakmak, Selvinar; Çakmak, İbrahim; ÇAKMAK, İBRAHİM; Mülkpınar, Emine; Toker, Mehmed Berk; TOKER, MEHMED BERK; Üstüner, Burcu; ÜSTÜNER, BURCU; Şen, Hasan; Nur, Zekariya; NUR, ZEKARİYA; Bursa Uludağ Üniversitesi/Veteriner Fakültesi; 0000-0002-1438-221X; AAH-2635-2021; AAH-2558-2021; AAG-7238-2021; A-2794-2014The aim of the current study was to determine the optimum concentration of bovine serum albumin for post-thawing quality of drone sperm and this is the first study to evaluate the effect of BSA supplemented TL-Hepes based extenders for drone semen cryopreservation. Sexually mature drones were used for semen collection. Pooled semen was diluted with TL-Hepes based extender supplemented with different concentrations of BSA (1 mg/mL, 3 mg/mL, and 5 mg/mL) or without BSA (control), at a final concentration of 100x10(6) spermatozoon/mL. Motility, plasma membrane functional integrity (HOST), and defected acrosome (PSA-FITC) were evaluated in the study. At post thaw, the highest sperm motility rates were obtained in the BSA5 group (P< 0.05). Functional integrity of sperm membrane was better preserved in the BSA3 and BSA5 groups compared to the other groups. The acrosomal integrity rates were higher in BSA5 group than in control group (P< 0.05). The study shows that bovine serum albumin supplemented TL-Hepes based extenders have beneficial effect on drone semen parameters at post-thaw. The results of the study demonstrated a notable advantage of using 5 mg/mL of BSA in TL-Hepes based extender.Publication Comparison and assessment of ovarian follicular dynamics during the breeding and non-breeding season in saanen goats(B W K Publishing Solutions & Verlag, 2020-01-01) Dogan, İbrahim; DOĞAN, İBRAHİM; Toker, Mehmed Berk; TOKER, MEHMED BERK; Alcay, Selim; ALÇAY, SELİM; Küçüksen, D. Udum; Bursa Uludağ Üniversitesi/Veteriner Fakültesi/Biyokimya Bölümü.; 0000-0003-1976-1814; A-2794-2014; R-8366-2018We describe and compare the ovarian follicular dynamics and plasma progesterone concentrations in nulliparous Saanen does during the breeding and non-breeding seasons. Does were monitored daily using transrectal ovarian ultrasonography for a full oestrous cycle in the breeding (n = 19) and a 21-day period in the non-breeding season (n = 20). At two-day intervals, blood samples were taken to determine plasma progesterone by ELISA. The pattern of follicular growth was characterised by four and five follicular waves in both seasons. Although the number of follicular waves was similar in the two seasons, the number of codominant follicles (p=0.027), the diameter of the largest follicle of waves 1 (p=0.036) and 4 (p=0.031), the duration of waves 3 (p=0.029) and 4 (p=0.034), the diameter of the largest follicle (p=0.042), the sums of the durations of all waves (p=0.037), the interwave interval (p=0.026) and the follicle growth rate (p=0.044) were higher in the breeding than in the non-breeding season. In addition, the numbers of small, medium and large follicles and the total number of all follicles of all waves differed between the seasons (p=0.037). In the breeding season, we found significant differences between the waves in the diameter of the largest follicles (p=0.042) and the duration of the waves (p=0.037); in the non-breeding season, no significant differences were found. Ovulatory follicles were most common in the fifth follicle wave. In the breeding season, the mean inter-oestrus and inter-ovulatory intervals and the numbers of ovulations after a synchronized oestrus with PGF2a were 21.47 +/- 0.19 days, 20.47 +/- 0.19 days and 1.84 +/- 0.86. The results indicate that follicular growth in Saanen goats during the breeding and non-breeding season is characterised by a wave-like pattern that differs between seasons.Publication Effect of gnrh treatment following a short-term estrous induction protocol on estrus and ovulation in saanen goats, during the transitional period(Hellenic Veterinary Medical Soc, 2020-10-01) Doğan, İbrahim; DOĞAN, İBRAHİM; Toker, Mehmed Berk; TOKER, MEHMED BERK; Alcay, Selim; ALÇAY, SELİM; Küçüksen, Duygu Udum; Bursa Uludağ Üniversitesi/Veteriner Fakültesi/Biyokimya Anabilim Dalı.; 0000-0003-1976-1814; R-8366-2018; A-2794-2014The objective of this study was to compare the effect on the ovulation time and estrus parameters of a GnRH agonist (buserelin acetate) administered 24 or 36 h following a short-term estrus induction and synchronization treatment in non-lactating Saanen goats during the transitional period. Goats received 20 mg FGA sponges for 6 days plus 300 IU eCG and 125 mu g d-cloprostenol 24 h prior to sponge removal. After removal of the sponges, goats were given either 1 ml physiological saline (0.9% NaCI) solution (Group 1; n = 9) after 12 h, 0.004 mg GnRH (Group 2; n = 10) after 24 h or 0.004 mg GnRH (Group 3; n = 10) after 36 h. The follicle development and ovulation in the ovaries were monitored by transrectal ultrasonography starting from the sponge application until the fifth day of the estrus cycle. Blood samples were collected on the same days to determine the plasma concentrations of progesterone (P-4) and estradiol (E-2). No statistical differences among groups were detected in any synchronization parameters, ultrasonic evaluations and plasma P-4 and E-2 concentrations. The evaluation of pooled data showed that the response of Saanen goats to treatments was comparable to the results of other published trials. Results of this study indicate that administration of GnRH at 24 h or 36 h after sponge removal, at the end of a short estrus induction and synchronization protocol, does not affect plasma P-4 and E-2 concentrations, estrus parameters and ovulation time in goats, during the transition period.