Ankara keçilerinde embriyo transfer uygulamaları
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The aims of this study were to compare the embryo recovery rate in Angora Goats based on application timing; at the beginning (October 2013; Group 1) and end (December 2013; Group 2) of the breeding season and to evaluate the viability and survivability of fresh or vitrified-thawed embryos when transferred. For this purpose, nine Angora Goats, mated with five fertile Angora Goat Bucks, were used as donors and thirthy Angora Goats were used as recipients. The study performed at the Ankara University Faculty of Veterinary Medicine Education and Research Farm according to the Ankara University Animal Experimentation Ethics Committee ethical approval. Donor goats were synchronized and superovulated with traditional protocol and were mated with fertile bucks. In traditional superovulation protocol; 0.33 gr progesterone containing device (CIDR®, Eazi-Breed, Animal Health) were applied intravaginally for 11 days, and FSH (Folltropin-V®, Bioniche Animal Health, 200 mg) was injected intramuscularly as six decreasing doses subsequent 9th day. In the protocol, one dose prostaglandin (Dalmazin®, Vetaş; 150 µg kloprostenol) was injected with FSH injection and one dose GnRH analog (Receptal®, Intervet; 8,4 µg) 24 hour after removing the progesterone containing device. Then goats were mated with fertile bucks 6-16 hours later following the GnRH injection. At the 156. hour of the mating, embryos were collected surgically and evaluated under a stereo microscope according to the criteria of the IETS (Internatioanl Embryo Transfer Society). At the beginning of the breeding season (Group 1), a total of 108 cells (49 Expanded Blastosist (ExpBl), 18 Blastosist (Bl), 27 Hatched Blastosist (HtcBl), 9 Degenerate Embryo and 5 unfertilised oocyte (UFO) were collected. On the other hand at the end of the breeding season (Group 2) 71 cells (15 Expanded Blastosist (ExpBl), 27 Blastosist (Bl), 14 Hatched Blastosist (HtcBl), 7 Degenerate Embryo and 8 Unfertilised oocyte (UFO) were collected in total from nine goats. Fresh or vitrified-thawed embryos were transferred surgically to synchronized recipients. In Group 1 fresh / thawed embryos were transferred to 15 / 15 goats and in group 2, fresh / thawed embryos were transferred to 8 / 8 goats, respectively. Each recipient received one or two embryos ipsilateral to the ovary containing one or more corpora lutea. On the 30th day of the transfer, goats were examined by transrectal ultrasonography, pregnancy rates of fresh / thawed embryos were 73.3% / 20% for group 1 and 100% / 37.5% for group 2. On the 90th day of the transfer, goats were examined again by ultrasonography, pregnancy rates were 46,6% / 0% for group 1 and 37,5%/0% for group 2, respectively. The total number of collected embryos at the beginning and end of the breeding season were analyzed using SPSS® (Version 14.01, SPSS Inc., Chicago, IL, USA) and for all comparisons, differences were considered with a minimum of %5 significance level. Descriptive statistics of all data were calculated and shown as 'mean ± standard error of mean'. Paired sample t test was used to evaluate the significant differences of means among the groups, after testing normality using Shapiro Wilk test and homogeneity of variances using Levene test as parametric test assumptions. After statistical analyses, the numbers of collected embryos at the beginning and at the end of the breeding season were compared. There was no difference in freezable/transferable embryo quality and this difference was found to be statistically significant (p<0,05). As a result, embryos could be collected after superovulation protocols in Angora Goats both at beginning and end of the breeding season, however there might be a decrease in numbers of collected embryos and the reasons for this might not be only the seasonal factors but also the previous superovulation protocols. The pregnancy rate following transfer of fresh embryos was satisfactory but not all does confirmed pregnant kidded - hence reducing the number of recipients kidding. The pregnancy rate following transfer of vitrified-thawed embryos was generally low and unsatisfactory. Further research is warrented in improving the cryopreservation techniques and thus the embryo survival rate of Angora Goat embryos.