Browsing by Author "Okut, Hayrettin"
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Item Associations between GH, PRL, STAT5A, OPN, PIT-1, LEP and FGF2 polymorphisms and fertility in holstein-friesian heifers(Kafkas Üniversitesi Veteriner Fakültesi Dergisi, 2017) Yılmaz, Onur; Okut, Hayrettin; Ata, Nezih; Öner, Yasemin; Yılmazbaş, Mecitoğlu Gülnaz; Keskin, Abdulkadir; Uludağ Üniversitesi/Ziraat Fakültesi/Zooteknik, Biyometri ve Genetik Bölümü.; Uludağ Üniversitesi/Veteriner Fakültesi.; 0000-0002-2904-8986; 0000-0003-2817-3221; ABB-3181-2020; AAG-4440-2019; 9634793800; 36457964000; 24473229800In this study, it was aimed to investigate polymorphisms in seven genes (GH, PRL, STAT5A, OPN, PIT-1, LEP and FGF2) related to reproductive traits in dairy heifers. Frequency distributions of the genotypes between fertile and repeat breeder heifers groups were investigated. Allele effects on fertility were also analyzed. Blood samples were taken from a total of 160 Holstein-Friesian heifers and they were divided into two groups according to their artificial insemination numbers (AI). The heifers becoming pregnant after the first AI were used as the fertile heifers (FH, n= 80) and the heifers with 3 or more equal AIs were accepted as the repeat breeder heifers (RBH, n= 80). All the animals were genotyped by the PCR-RFLP method for seven genes and the association works were performed for 145 animals (RBH, n= 79; FH n= 66). For all loci investigated, two alleles and three genotypes were found for overall population with the exception that PRL locus had two alleles and two genotypes. The chi-square test (.2) revealed that the whole population and the two groups separately were at Hardy-Weinberg equilibrium. The genotype distributions of PIT-1 and STAT5A conspicuously differed between the FH and the RBH groups; however, these differences were not found significant. Association of GH-AB genotype was found significant on AI number for the first pregnancy. Mixed effect logistic regression model was used to investigate the allele effects on fertility. No linkage disequilibrium was detected between the investigated loci.Item Comparing conception rate of the repeat breeder vs. normal dairy cows following a combined treatment protocol during the warm season(Wiley, 2010-09) Çevik, Sait; Okut, Hayrettin; Keskin, Abdülkadir; Yılmazbaş, Gülnaz Mecitoğlu; Gümen, Ahmet; Karakaya, Emre; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; 0000-0003-2817-3221; AAG-4440-2019; AAH-1406-2021; AAH-3831-2021Item Comparison of responses to Ovsynch between Holstein-Friesian and Swedish Red cows(Elsevier, 2010) Çelik, Yakup; Okut, Hayrettin; Wiltbank, Milo Charles; Keskin, Abdülkadir; Yılmazbaş, Gülnaz Mecitoğlu; Gümen, Ahmet; Karakaya, Ebru Bilen; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; 0000-0003-2817-3221; AAH-1406-2021; AAG-4440-2019; AAH-3831-2021; 24473229800; 36457964000; 6602393069; 36457784500The Ovsynch protocol was designed to synchronize ovulation, thereby allowing timed artificial insemination (TAI) of all cows without detection of estrus. However, the effectiveness of Ovsynch in different breeds of dairy cows has not been previously compared. The aim of this study was to compare the response to Ovsynch in cycling lactating Holstein-Friesian (HF) and Swedish Red (SR) dairy cows. A total of 495 cyclic cows (n=347 HF, n=148 SR) were housed together and treated with Ovsynch (GnRH - 7 d - PGF2α - 56h - GnRH - 16 to 18h - TAI). Ovulatory responses, synchronization rate, maximal follicle size at the time of AI, and percentage of pregnant cows per AI (P/AI at 31 and 62 d after AI) were compared between breeds. Ultrasonography was performed during Ovsynch at first GnRH, PGF2α, at time of AI, and 7 d after AI. Ovulatory response and synchronization rate were similar in HF versus SR cows (60.2 vs. 62.2%; 88.4 vs. 88.5%, respectively). Cows that ovulated to the first GnRH of Ovsynch had smaller follicle size at AI (15.9±0.1 vs. 16.4±0.2mm). Maximal follicle size at AI was greater for HF (16.4±2.2mm) than SR (15.5±2.3mm) cows. The P/AI was greater for SR than HF cows at the 62-d pregnancy diagnosis (56.1 vs. 46.1%). In addition, pregnancy loss between 31 and 62 d of pregnancy was greater in HF (10.1%) than SR (3.5%) cows. Fertility was less in HF cows during the hot season (57.7 in cold vs. 38.1% in the hot season), whereas such a decrease was not observed in SR (60.0 in cold vs. 53.5% in the hot season) cows. Thus, although the GnRH treatments of Ovsynch were equally effective in SR and HF cows, pregnancy outcomes (P/AI at d 62 and pregnancy survival) were greater in SR than HF cows, and P/AI in SR cows was not compromised during the hot season as was found for HF cows.Item Comparison of responses to Ovsynch between Holstein-Friesian and Swedish Red cows(Elsevier Science, 2011-04) Çelik, Yakup; Okut, Hayrettin; Wiltbank, Milo Charles; Keskin, Abdülkadir; Mecitoğlu, Gülnaz Yılmazbaş; Gümen, Ahmet; Karakaya, Ebru; Uludağ Üniversitesi/Veterinerlik Fakültesi/Kadın Hastalıkları ve Doğum Anabilim Dalı.; 0000-0003-2817-3221; AAH-1406-2021; AAG-4440-2019; AAH-3831-2021; 24473229800; 36457964000; 6602393069; 36457784500The Ovsynch protocol was designed to synchronize ovulation, thereby allowing timed artificial insemination (TAI) of all cows without detection of estrus. However, the effectiveness of Ovsynch in different breeds of dairy cows has not been previously compared. The aim of this study was to compare the response to Ovsynch in cycling lactating Holstein-Friesian (HF) and Swedish Red (SR) dairy cows. A total of 495 cyclic cows (n = 347 HF, n = 148 SR) were housed together and treated with Ovsynch (GnRH - 7 d - PGF(2 alpha) - 56 h - GnRH - 16 to 18 h - TAI). Ovulatory responses, synchronization rate, maximal follicle size at the time of AI, and percentage of pregnant cows per AI (P/AI at 31 and 62 d after AI) were compared between breeds. Ultrasonography was performed during Ovsynch at first GnRH, PGF(2 alpha), at time of AI, and 7 d after AI. Ovulatory response and synchronization rate were similar in HF versus SR cows (60.2 vs. 62.2%; 88.4 vs. 88.5%, respectively). Cows that ovulated to the first GnRH of Ovsynch had smaller follicle size at AT (15.9 +/- 0.1 vs. 16.4 +/- 0.2 mm). Maximal follicle size at AT was greater for HF (16.4 +/- 2.2 mm) than SR (15.5 +/- 2.3 mm) cows. The P/AI was greater for SR than HF cows at the 62-d pregnancy diagnosis (56.1 vs. 46.1%). In addition, pregnancy loss between 31 and 62 d of pregnancy was greater in HF (10.1%) than SR (3.5%) cows. Fertility was less in HF cows during the hot season (57.7 in cold vs. 38.1% in the hot season), whereas such a decrease was not observed in SR (60.0 in cold vs. 53.5% in the hot season) cows. Thus, although the GnRH treatments of Ovsynch were equally effective in SR and HF cows, pregnancy outcomes (P/AI at d 62 and pregnancy survival) were greater in SR than HF cows, and P/AI in SR cows was not compromised during the hot season as was found for HF cows.Item Comparison of synchronisation and fertility after different modifications of the ovsynch protocol in cyclic dairy cows(Akademiai Kiado Zrt, 2012-12-11) Koç, Volkan; Okut, Hayrettin; Yilmazbaş-Mecitoğlu, Gülnaz; Karakaya-Bilen, Ebru; Keskin, Abdülkadir; Gümen, Ahmet; Uludağ Üniversitesi/Veteriner Fakültesi/Kadın Hastalıkları ve Doğum Anabilim Dalı.; 0000-0003-2817-3221; 0000-0003-4837-1858; AGY-3496-2022; AAG-4440-2019; AAH-1406-2021; AAH-3831-2021; 36457964000; 36457784500; 24473229800; 6602393069The objectives of this study were to evaluate the effects of (1) double doses of PGF(2 alpha) administration or (2) an exogenous progesterone (CIDR) applied concurrently with, or (3) the day after, first GnRH of Ovsynch (GnRH-1), on synchronisation and fertility during the Ovsynch protocol. All cows (n = 378) received the Ovsynch protocol (GnRH-7d-PGF(2 alpha)-56h-GnRH-18h-TAI). The 'OVS' group (n = 105) received only the Ovsynch protocol. The 'OVS-PGF' group (n = 118, GnRH-7d-PGF(2 alpha)-12h-PGF(2 alpha)-44h-GnRH-18h-TAI) received an extra dose of PGF(2 alpha) 12 h later on Day 7. The 'OVS-7CIDR' group (n = 78, GnRH+CIDR-7d-PGF(2 alpha)-56h-GnRH-18h-TAI) received a CIDR for 7 days between GnRH-1 and PGF(2 alpha). In the 'OVS-6CIDR' group (n = 77, GnRH-24h-CIDR-6d-PGF(2 alpha)-56h-GnRH-18h-TAI), CIDR was applied one day after GnRH-1 and removed 6 days later. When all cows were evaluated, the responses to GnRH-2 were higher (P = 0.005) in cows that responded to GnRH-1 (95.4%) compared to the cows that did not respond (87.6%). The pregnancy rates at 31 and 62 days for each group were 48.6% and 42.9% in the OVS, 54.2% and 52.5% in the OVS-PGF, 52.6% and 48.7% in the OVS-7CIDR, and 55.8% and 49.3% in the OVS-6CIDR groups. Thus, none of the three different treatments has an effect on increasing the outcomes of the Ovsynch protocol in cyclic lactating dairy cows.Item Conception rate after timed artificial insemination protocols using by PGF(2 alpha) and GnRH in dairy heifers(Wiley, 2010-09) Alkan, Ali; Güzeloğlu, Aydın; Okut, Hayrettin; Gümen, Ahmet; Keskin, Abdülkadir; Yılmazbaş, Gülnaz Mecitoğlu; Karakaya, Emre; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; 0000-0003-2817-3221; AAH-1406-2021; AAG-4440-2019; AAH-3831-2021Item Effect of hCG vs. GnRH at the beginning of the Ovsynch on first ovulation and conception rates in cyclic lactating dairy cows(Elsevier, 2010-09-01) Darıcı, R.; Okut, Hayrettin; Keskin, Abdülkadir; Yılmazbaş Mecitoğlu, Gülnaz; Gümen, Ahmet; Karakaya Bilen, Ebru; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; 0000-0003-2817-3221; AAH-3831-2021; AAH-1406-2021; AAG-4440-2019; 24473229800; 36457964000; 6602393069; 36457784500Ovulatory response to the first GnRH of Ovsynch is a very important factor for determining the outcome of a successful synchronization. The aim of the present study was to develop a protocol to increase the percentage of cows that ovulated in response to the first administration of Ovsynch. This study was designed to compare ovulation rates in response to GnRH or hCG at the beginning of Ovsynch and to evaluate the effects of this manipulation on pregnancy. Cows (n = 371) with corpus luteum (CL) and at least one follicle greater than 10 mm diameter size on either ovary were included in the study. Cows were divided into two groups. The Ovsynch protocol began with GnRH (10 mu g) in the GPO group (n = 161; GnRH-7d-PGF2 alpha-56h-GnRH-18h-AI), whereas in the HPG group, the first GnRH of the Ovsynch was replaced with 1500 IU hCG (n = 210; hCG-7d-PGF2 alpha-56h-GnRH-18h-AI). Ovarian ultrasonography was performed at the times of GnRH or hCG and of PGF2 alpha administration, at the time of artificial insemination (AI) and seven days after Al, to determine ovulation. Maximal follicle size at the beginning of the Ovsynch did not affect on response to the first GnRH/hCG treatment. Conception rate (31 d) was 0.6 times more likely to be higher (P < 0.001) in cows that responded to the first hormonal administration of Ovsynch than in those that did not respond (95% CI = 0.29-0.71). Conception rate was found to be different between the HPG (37.6%, 79/210) and the GPO groups (48.4%, 78/161). Thus, beginning of the Ovsynch protocol with hCG did not increase ovulation and conception rate in lactating dairy cows, suggesting that hCG is not a suitable replacement of the first GnRH of Ovsynch. However, our results do show that increasing the ovulation rate in response to the first hormonal administration of Ovsynch can have a significant effect on conception rate.Item The effect of intrauterine cephapirin treatment after insemination on conception rate in repeat breeder dairy cows subjected to the progesterone-based Ovsynch protocol(TÜBİTAK, 2012) Alkan, Ali; Taşdemir, Umut; Okut, Hayrettin; Gümen, Ahmet; Mecitoğlu, Gülnaz Yılmazbaş; Keskin, Abdulkadir; Karakaya, Ebru; Uludağ Üniversitesi/Veteriner Fakültesi/Jinekoloji ve Doğum Anabilim Dalı.; 0000-0003-2817-3221; AAG-4440-2019; AAH-1406-2021; AAH-3831-2021; 6602393069; 36457964000; 24473229800; 36457784500Subclinical endometritis contributes to repeat breeder syndrome in dairy cows. This study evaluated the effect of intrauterine cephapirin benzathine administration aft er timed artificial insemination (TAI) on the conception rate (CR) in repeat breeder dairy cows. To determine the antibiotic effects, all cows (n = 335) that had more than 3 services with no clinical abnormalities of the reproductive tract received the same combined synchronisation protocol: an ear implant containing progestagen using the Ovsynch protocol and a third gonadotropin-releasing hormone (GnRH) administration 7 days aft er TAI. Cows in the treatment group (TRT; n = 160) received intrauterine cephapirin 12 h aft er TAI, and cows in the control group (CON; n = 175) did not receive intrauterine antibiotics. The percentage of cows that responded to the first (67.5% in TRT, 70.9% in CON) and second (98.8% in TRT, 97.1% in CON) GnRH of Ovsynch was similar between the groups. In addition, the response to the third GnRH administration aft er TAI (88.1% in TRT, 83.9% in CON) did not differ between the groups. However, there was no effect of the cephapirin administration on CR on days 31 and 62 in the repeat breeder cows (43.8% in TRT and 44.0% in CON; 39.4% in TRT and 40.6% in CON, respectively). Thus, post-TAI intrauterine cephapirin administration was not found to be useful for the treatment of potential subclinical endometritis in repeat breeder dairy cows.Item The effect of ovulatory follicle size at the time of insemination on pregnancy rate in lactating dairy cows(TÜBİTAK, 2015-09-28) Okut, Hayrettin; Keskin, Abdulkadir; Mecitoğlu, Gülnaz; Bilen, Ebru; Güner, Barış; Orman, Abdulkadir; Gümen, Ahmet; Uludağ Üniversitesi/Veteriner Fakültesi/Jinekoloji ve Doğum Anabilim Dalı.; Uludağ Üniversitesi/Veteriner Fakültesi/Zootekni Anabilim Dalı.; 0000-0001-9138-4422; 0000-0003-2817-3221; AAG-9134-2021; AAG-4440-2019; AAH-1406-2021; AAH-3831-2021; 24473229800; 36457964000; 57040965000; 57188841418; 24335834100; 6602393069The aims of this study were to determine the factors that affect follicle size at the time of artificial insemination (AI) and to detect the relationship between ovulatory follicle size at the time of AI and pregnancy rate in dairy cows. A total of 1428 follicle size measurements were obtained from Holstein-Friesian (HF) and Swedish Red (SR) cows that were inseminated with the fixed-timed AI protocols used in this study. Follicle size was affected by breed (P - 0.0001), milk production (P - 0.01), parity (P - 0.05), and season (P = 0.04). Follicle size was greater (P = 0.0001) in the HF (15.55 mm) than the SR cows (14.88 mm). Multiparous cows had larger (P = 0.04) follicles (15.35 mm) than the primiparous cows (15.07 mm). Cows with follicle sizes between 13.5 and 17.5 mm were more likely to be pregnant than cows with other sizes follicles (P < 0.01). Embryonic loss was lower (P < 0.01) in cows with follicle sizes between 13.5 and 16.5 mm. Thus, the follicle size was affected by breed, milk production, parity, and season. Pregnancy and embryonic loss in lactating dairy cows were significantly related to follicle size.Item Effect of post-ai cephapirin on conception rate in repeat breeder cows(Wiley, 2010-09) Çelik, Yakup; Okut, Hayrettin; Yılmazbaş, Gülnaz Mecitoğlu; Keskin, Abdülkadir; Karakaya, Emre; Gümen, Ahmet; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; 0000-0003-2817-3221; AAH-3831-2021; AAG-4440-2019; AAH-1406-2021Item The effect of preovulatory follicle size at the time of insemination on pregnancy in lactating dairy cows(Wiley, 2011-09) Çelik, Yakup; Okut, Hayrettin; Wiltbank, Milo C.; Keskin, Abdulkadir; Mecitoğlu, Gülnaz Yılmazbaş; Karakaya, Emre; Gümen, Ahmet; Uludağ Üniversitesi/Veterinerlik Fakültesi/Veterinerlik Doğum ve Jinekolojisi Anabilim Dalı.; 0000-0003-2817-3221; AAH-3831-2021; AAG-4440-2019; AAH-1406-2021; 36457964000Item Effect of presynchronization strategy before ovsynch on fertility at first service in lactating dairy cows(Elsevier Science, 2012-11) Alkan, Ali; Okut, Hayrettin; Wiltbank, Milo Charles; Gümen, Ahmet; Keskin, Abdülkadir; Yılmazbaş, Gülnaz Mecitoğlu; Karakaya, Ebru; Uludağ Üniversitesi/Veteriner Fakültesi/Jinekoloji ve Doğum Anabilim Dalı.; 0000-0003-2817-3221; AAH-1406-2021; AAG-4440-2019; AAH-3831-2021; 6602393069; 24473229800; 36457964000; 36457784500The aim of this study was to evaluate the effect of presynchronization with or without the detection of estrus on first service pregnancy per artificial insemination (P/AI) and on Ovsynch outcome in lactating dairy cows. A total of 511 cows were divided randomly but unevenly into 3 treatment groups at 44 to 50 days in milk (DIM). Ovsynch was started at the same time (69 to 75 DIM) in all three groups. Cows in the Ovsynch group (CON, N = 126) received no presynchronization before Ovsynch, and all cows were bred by timed AT (TAI). Cows in the presynchronization with estrus detection (PED) and the presynchronization with only TAI (PTAI) groups received two doses of prostaglandin F-2 alpha (PGF) 14 days apart, starting at 44 to 50 DIM. Ovsynch was initiated 11 days after the second PGF treatment. Cows in the PED group (N = 267) received AI if estrus was detected after either PGF injection. Cows that were not determined to be in estrus after PGF injection received Ovsynch and TAI. Cows in the PTAI group (N = 118) were not inseminated to estrus, with all cows receiving TAI after Ovsynch. The ovulatory response to the first GnRH injection administered as part of Ovsynch differed (P = 0.002) among treatment groups (83.1% in PTAI, 72.6% in PED, and 62.7% in CON). However, the ovulatory response to the second injection of GnRH during Ovsynch did not differ among treatment groups. Of the 267 PED cows, a total of 132 (49.4%) exhibited estrus and were inseminated. The P/AI at the 31-day pregnancy diagnosis was similar between the cows in the PED group with AI after estrus detection (37.9%; 50/132) and those bred with TAI (34.1%; 46/135). The P/AI in the CON group (46.8%; 59/126) was greater (P < 0.05) than that in the PED group (36.0%; 96/267). In addition, the P/AI in the CON group was greater (P = 0.04) than that in the PED cows receiving TAI (34.1%; 46/135) but less than that in the PED cows bred to estrus (37.9%; 50/132) (P = 0.16). At the 31-day pregnancy diagnosis, the cows in the PTAI group had greater P/AI (55.9%; 66/118) than both those in the PED group (P < 0.01; either estrus or TAI) and those in the CON group (P = 0.08). Thus, presynchronization with PGF (PTAI) increased the ovulatory response to Ovsynch and improved P/AI in dairy cows. Interestingly, the breeding of cows to estrus during presynchronization reduced fertility to the TAI and overall fertility, including cows bred to estrus and TAI. These results indicate that maximal fertility is obtained when all cows receive TAI after the presynchronization protocol.Item The effect of progesterone based ovsynch protocol and gnrh treatment after artificial insemination on conception rate in repeat breeder cows(Uludağ Üniversitesi, 2010-12-30) Taşdemir, Umut; Çelik, Yakup; Okut, Hayrettin; Keskin, Abdulkadir; Gümen, Ahmet; Mecitoğlu, Gülnaz Yılmazbaş; Karakaya, Ebru; Uludağ Üniversitesi/Veteriner Fakültesi.The aim of this study was to test the combined treatment protocol for improving fertility in repeat breeder cows by eliminating most of the hormonal etiological factors. Total 238 clinically healthy lactating dairy cows were included in the study; 175 dairy cows had more than three services (Repeat Breeder Cows) and 63 dairy cows had less than three services (Normal Cows). Ovsynch protocol was applied at random stages of the estrous cycle to all cows and exogenous progesterone (ear implant) was applied between GnRH and PGF2α of Ovsynch. In addition, GnRH was administrated seven days after artificial insemination (GnRH–progesterone– 7d–PGF2α–2d–GnRH–16h–AI–7d–GnRH). Response to the first GnRH of Ovsynch was greater (P<0.003) in repeat breeders (70.9%) than in normal cows (49.2%). However percentages of cows to responded to 2nd and 3rd GnRH were not different between groups (97.1%, 83.9% in repeat breeders and 98.4%, 87.1% in normal cows, respectively). Conception rates were similar at 31 and 62 d between groups (44.0%, 40.6% in repeat breeders and 47.6%, 42.9% in normal cows, respectively). In addition, embryonic loss was also similar in groups (7.8% in repeat breeders and 10.0% in normal cows). Thus, conception rate and response to hormonal treatments of the combined protocol except first GnRH were found to be similar in both repeat breeder and normal cows. So the combined protocol could be effective treatment for improving conception rate in repeat breeder cows.Item Effects of presynchronization with gonadotropin-releasing hormone-prostaglandin F-2 alpha or progesterone before Ovsynch in noncyclic dairy cows(Elsevier Science, 2012-12) Alkan, Ali; Okut, Hayrettin; Yılmazbaş, Gülnaz Mecitoğlu; Karakaya, Ebru; Keskin, Abdülkadir; Gümen, Ahmet; Uludağ Üniversitesi/Veteriner Fakültesi/Jinekoloji ve Doğum Anabilim Dalı.; 0000-0003-2817-3221; AAH-3831-2021; AAG-4440-2019; AAH-1406-2021; 36457964000; 36457784500; 24473229800; 6602393069The aim of this study was to evaluate the efficiency of presynchronization with GnRH and PGF(2 alpha) or with progesterone on overall Ovsynch (OVS) outcomes in noncyclic dairy cows. Cows were scanned 7 d apart with ultrasonography to determine cyclicity. Noncyclic cows (n = 281; no corpus luteum on ovaries at both examinations) were randomly divided into 3 groups. In the GP group (n = 108), the cows received GnRH and PGF(2 alpha) (PGF) administrations 7 d apart, and OVS was started 11 d after PGF (GnRH-7 d-PGF-11 d-OVS). In the P4 group (n = 90), the cows were treated for 7 d with an intravaginal progesterone (P4) implant (PRID), and then OVS was started 11 d after removal of the implant (7 d PRID-11 d-OVS). The control group (CON, n = 83) did not receive any presynchronization, and OVS was started at the same time as in the other groups (18 d-OVS). The percentage of cows that became cyclic at the beginning of OVS was lower in the CON group (38.6%; 32/83) than in the presynchronization groups (66.7%, 72/108 in GP; 71.1%, 64/90 in P4). The response to the first GnRH of OVS did not differ among groups (63.9%, 53/83 in CON; 67.6%, 73/108 in GP; 63.3%; 57/90 in P4), and synchronization rates were similar among the groups (74-82%). The cows that responded to presynchronization treatments (GP or P4) had higher pregnancy per artificial insemination (P/AI) than did nonresponding cows. Pregnancy per AI at 31 d did not differ between groups (30.1%, 25/83 in CON; 43.5%, 47/108 in GP; and 35.6%, 32/90 in P4). However, CON cows (24.1%, 20/83) had lower P/AI at 62 d than GP cows (41.7%, 45/108). Embryonic loss was higher in CON (20%, 5/25) compared with the P4 group (3%, 1/32). The administration of GnRH followed by PGF or exogenous progesterone (PRID) similarly increased the percentage of cows that became cyclic before Ovsynch in noncyclic cows, but fertility did not improve. However, the cows that responded to presynchronization had higher fertility rates than the nonresponding cows.Item Effects of presynchronizations with GnRH/PGF(2 alpha) vs. progesterone before Ovsynch in noncyclic dairy cows(Elsevier, 2010) Darıcı, R.; Okut, Hayrettin; Yılmazbaş, Gülnaz Mecitoğlu; Keskin, Abdülkadir; Gümen, Ahmet; Karakaya, Ebru; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Öncesi Bilimler Bölümü.; 0000-0003-2817-3221; AAH-3831-2021; AAH-1406-2021; AAG-4440-2019Item Effects of reducing interval from GnRH to PGF(2 alpha) in Ovsynch protocol on pregnancy rate in cyclic lactating dairy cows(Elsevier, 2010) Çelik, Yakup; Okut, Hayrettin; Gümen, Ahmet; Yılmazbaş, Gülnaz Mecitoğlu; Keskin, Abdülkadir; Karakaya, Emre; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Bilimler Bölümü.; Uludağ Üniversitesi/Veterinerlik Fakültesi/Klinik Öncesi Bilimler Bölümü.; 0000-0003-2817-3221; AAG-4440-2019; AAH-1406-2021; AAH-3831-2021Item Improving conception rate in lactating dairy cows by using modified ovsynch protocol during summer(Uludağ Üniversitesi, 2012-01-24) Tasdemir, Umut; Alkan, Ali; Okut, Hayrettin; Mecitoglu, Gulnaz Yılmazbas; Gumen, Ahmet; Keskın, Abdulkadir; Karakaya, Ebru; Uludağ Üniversitesi/Veteriner Fakültesi.The aim of this study was to test two different timed artificial insemination (AI) protocols in order to improve the percentage of pregnant cows per AI in lactating dairy cows during the summer. Cows (n=140) were randomly divided into two groups; cows in the OVS group (n=75) received the Ovsynch protocol (GnRH–7d–PGF2α–2d–GnRH–16h–AI), and cows in the MOVS group (n=65) received the Ovsynch protocol with exogenous progesterone (P4) which administrated between GnRH and PGF2α. In addition, GnRH was injected 7 d after AI in the MOVS group (GnRH–P4–7d –PGF2α–2d–GnRH–16h–AI–7d–GnRH). Response to the second GnRH treatment of Ovsynch (GnRH-2) was greater (P<0.03) in the MOVS (98.5%) than the OVS (89.3%) group. Although P/AI at 31 d was numerically greater in the MOVS (46.2%, 30/65) than the OVS (37.3%, 28/75) group, this difference was statistically insignificant. Thus, because of the greater response to GnRH-2 and P/AI in MOVS compared with the OVS group, the MOVS protocol can be used to improve P/AI in lactating dairy cows during the summer, but further studies are needed to be evaluated the effects of the MOVS protocol on P/AI during the summer.Item Siklik ve siklik olmayan sütçü ineklerde ovsynch protokolüne verilen yanıtın karşılaştırılması(Uludağ Üniversitesi, 2010-11-26) Taşdemir, Umut; Alkan, Ali; Okut, Hayrettin; Keskin, Abdulkadir; Mecitoğlu, Gülnaz Yılmazbaş; Karakaya, Ebru; Gümen, Ahmet; Uludağ Üniversitesi/Veteriner Fakültesi.Ovsynch protokolü, iki GnRH ve bir PGF2α uygulamasından oluşan ve ovulasyonu sinkronize eden zaman ayarlı suni tohumlama (ST) protokolüdür (GnRH–7gün-PGF2α–56saat–GnRH–18 saat-ST). Bu protokolün avantajı, östrus tespitine gerek kalmadan ST’ye olanak sağlamasıdır. Yapılan çalışmalarda Ovsynch protokolü hem siklik hem de siklik olmayan ineklerde ovulasyonu başarılı bir şekilde sinkronize etmesine rağmen, elde edilen gebelik oranlarında farklılıklar mevcuttur. Bu çalışmanın amaçları; 1) siklik olmayan ineklerde Ovsynch öncesi en büyük follikül çapını belirlemek 2) siklik olmayan ineklerde follikül çapının Ovsynch sonuçları üzerine etkisini saptamak 3) siklik ve siklik olmayan ineklerde Ovsynch protokolüne verilen yanıtı karşılaştırmaktı. İneklerin siklik olup olmadıklarını saptamak amacıyla 7 gün arayla iki kez ovaryumların ultrasonografik muayenesi yapıldı. Çalışma, 181 baş siklik, 69 baş ise siklik olmayan toplam 250 baş inekte gerçekleştirildi. Siklik olmayan ineklerde Ovsynch öncesi en büyük follikül çapı 16-24 mm olan inek oranı (%44.9), 9-15 mm (P<0.05; %28.9) ve ≥ 25 mm (P<0.01; %26.0) follikül çaplarına sahip ineklerin oranından daha yüksek saptandı. Ovsynch’in ilk GnRH’na alınan yanıt, siklik olmayan ineklerde (%97.1, 67/69) siklik ineklere (%57.5, 104/181) göre daha fazla saptandı (P<0.0004). Ovsynch’in ikinci GnRH’ına yanıt, siklik (%88.4,160/181) ve siklik olmayan (%85.5, 59/69) ineklerde benzer tespit edildi. Aynı zamanda 31. gün gebelik oranında siklik (%39.8, 72/181) ve siklik olmayan (%31.9, 22/69) inekler arasında fark bulunmadı. Bununla birlikte ≥25 mm follikül çapına sahip siklik olmayan ineklerin Ovsynch’in ikinci GnRH’ına yanıtı ve gebelik oranı (sırasıyla; %100 ve %55.5), follikül çapı 9-15 mm (sırasıyla; %75.0 ve %15.0) ve 16-24 mm (sırasıyla; %83.8 ve %29.0) olan ineklere göre daha yüksek saptandı. Sonuç olarak, siklik olmayan ineklerin Ovsynch protokolüne en az siklik inekler kadar yanıt verdiği ve Ovsynch başlangıcında siklik olmayan ineklerde en büyük follikül çapının ikinci GnRH’a yanıtı ve gebelik oranını etkilediği saptandı.