154 EVALUATION OF EMBRYO RECOVERY RATE AND EMBRYO TRANSFER IN ANGORA GOATS

Abstract

The aims of this study were to compare the embryo recovery rate in Angora goats based on application timing; at the beginning (September – October; Group 1) and end (December; 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 were used as donors and thirthy Angora goats were used as recipients. Donor goats were synchronized and superovulated with traditional protocol and were mated with fertile bucks. At the 156th hour of the mating, embryos were collected surgically and evaluated under a stereo microscope. In group 1, 103 embryos and in group 2, 63 embryos were collected 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 1 or 2 embryos ipsilateral to the ovary containing one or more corpora lutea. On day 30 of the transfer, goats were examined by transrectal ultrasonography, pregnancy rates of fresh/thawed embryos were 66.6%/26.6% for group 1 and 62.5%/62.5% for group 2. On day 100 of the transfer, goats were examined again by ultrasonography, and pregnancy rates were 46.6%/0% for group 1 and 37.5%/0% for group 2, respectively. After about 50 days, goats were kidded. In group 1, 3 twins and 4 single kids were born; in group 2, 2 twins were born. The total number of collected embryos and pregnancy rates among the groups were analysed using SPSS^® (version 14.01, Chicago, IL, USA) and for all comparisons, differences were considered with a minimum of 5% significance level. 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. 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 environment, care, nutrition and 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.

This study was financed with the University of Ankara Grant.