Studies on superovulatory response and conception rate in sheep using embryo transfer technology
Loading...
Date
2020-11-23
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Sher-e-Kashmir University of Agricultural Sciences & Technology, Jammu (J&K)
Abstract
Superovulatory response and embryo recovery was evaluated in 39 donor ewes using FSH in six decreasing dose schedule in four groups (Group I: FSH 80 mg + eCG 200 IU, n=11; Group II: FSH 80 mg + eCG 200 IU + hCG @500IU, n=9; Group III: FSH 100 mg + eCG 200 IU, n=10; and Group IV: FSH 100 mg + eCG 200 IU + hCG @500IU, n=9). Surgical embryo collection and transfer was performed after 5-6 day of mating of donors. Blood samples of donor and recipient ewes were evaluated for blood biochemical parameters and progesterone on day 0 (Collection I), 10 days after progesterone implant (Collection II), on the day of estrus (Collection III) and on the day of embryo transfer/collection (Collection IV). The mean estrus onset in donor ewes group varied between 11.25±1.47 to 16.00±2.00 hrs while in recipients it was 22.61±1.34 hrs after sponge removal. The Group II ewes showed significantly higher (p<0.05) mean ovulations (8.43±1.93) and total ovarian response (11.43±2.81) per ewe compared to the Group III (4.30±1.44 CL; 6.60±1.40 total ovarian response). The high dose of FSH (100 mg) without hCG had slightly increased mean ovulations and total ovarian response, embryo recovery %, but number of ewes showing superovulation and fertilization % was decreased. The hCG addition in the @ 80 mg FSH schedule had significantly (p<0.05) high number of ovulations, and total ovarian response in superovulating ewes though the fertilization % was improved on its addition at higher dose of FSH (100 mg), but with compromised embryo recovery %. The hCG was not effective in decreasing number of unfertilized ovum and had not improved transferable embryo numbers. A significant (p<0.05) rise in the level of blood glucose was recorded at estrus, while blood biochemical parameters varied with no sigificant (p>0.05) effect on the superovulation capacity of the ewes. There was significantly (p<0.05) positive correlation between the total protein (initial values and at estrus) and the estrus onset time, while negative correlation was recorded with blood glucose at estrus with the number of anovulatory follicles (p<0.05); and with the total ovarian response (p<0.01). The initial values of total protein were correlated positively with the total ovarian response and negatively with the transferable embryos. There were negative correlations at Collection IV, between transferable embryos with blood albumin and degenerated embryos with the initial creatinine levels. The superovulating ewes had significantly (p<0.05) high P4 level on the day of embryo collection. The initial level of blood progesterone had significantly (p<0.05) high negative correlation with the estrus onset time and positive (p<0.01) with the number of transferable embryos in the donor ewes. Conception rate after three embryo transfer was higher as compared to one and two embryos per recipient. Transfer of quality fresh embryos resulted in successful lambing with 23.33 % efficacy of the embryo transfer which was higher in the triplet embryo transfer followed by twin and single embryo transfers. Lamb survival after two and three embryo transfer was satisfactory. No significant (p>0.05) differences were observed in the blood progesterone level between the conceived and non-conceived groups at all the collection days. It may be recommended to use Folltropin-V (FSH) @ 80 mg (NIH-FSH-P1) without hCG for superovulation and to practice Grade A twin embryo transfer per recipient ewe. Future research should be aimed to improve the superovulatory response, embryo recovery rate, conception rate and lambing rate in sheep.
Description
Studies on superovulatory response and conception rate in sheep using embryo transfer technology