การประเมินการเปลี่ยนแปลงของฟอลลิเคิลบนรังไข่ เซลล์วิทยาของช่องคลอด และความสมบูรณ์พันธุ์ในแพะเพศเมียที่ได้รับโปรแกรมฮอร์โมนโปรเจสเตอโรนพื้นฐานแบบระยะสั้นเพื่อกำหนดเวลาการผสมเทียม

Abstract

The short-term progesterone-based protocol is the basic reproductive technology that can be used to enhance reproductive management and vaginal cytology is a common technique that widely used to estimate the optimal mating time and estrous cycle. However, the study of ovarian follicular dynamics, vaginal cytology, and fertility in female goats received the short-term progesterone-based protocol for fixed-time artificial insemination has been limited. Therefore, the aim of this study was to compare the ovarian follicular dynamics, vaginal cytology, and fertility in female goats received the different short-term progesterone-based protocol for fixed-time artificial insemination. In experiment 1, 60 female goats were randomized into 3 groups: T1 (P4 + PGF + PMSG; n=20), T2 (P4 + PGF + PMSG + GnRH; n=20), and T3 (P4 + PGF + PMSG + 2GnRH; n=20). At the initiation of the short-term progesterone (P4)-based synchronization protocol (day 0), female goats in T1 and T2 received normal saline while female goats in T3 received GnRH injection. All female goats received intravaginal inserts of synthetic P4 (controlled internal drug release; CIDR) for 5 days (day 0 to day 5). On day 5, CIDR was removed from vagina, PGF2α and PMSG were injected. On day 7, female goats in T1 received normal saline while female goats in T2 and T3 received GnRH injection. Ovarian follicular wave emergency and follicular growth were evaluated using transrectal ultrasound. Blood samples were collected from each female goat to analyze plasma P4 concentration. In experiment 2, 368 female goats were randomized into 2 groups that received the effective synchronization protocol from experiment 1: P4 + PGF + PMSG + GnRH (T2, n=168) and P4 + PGF + PMSG + 2GnRH (T3, n=200) protocols. All female goats were inseminated with FTAI on day 7 and day 8 and diameter of follicle and follicle population were evaluated using transrectal ultrasound. Blood samples were randomly collected to analyze plasma estradiol concentration. Wet smears of 53 female goats were prepared from vaginal epithelium cells, stained with Diff-Quick, and evaluated microscopically for presence and type of vaginal epithelial cells (parabasal, small intermediate, large intermediate, nucleated superficial and anucleated superficial cells). All inseminated female goats were diagnosed as pregnant at 30 days after insemination. In results of experiment 1, the proportion of goat exhibiting estrus and preovulatory follicle size did not differ among treatment groups (P>0.05). However, the proportion of goat exhibiting ovulation was greater in T3 (95%) compared with T1 (70%) but was not different when compared with T2 (85%; P<0.05). Ovulation times of first ovulatory follicle in all groups were the highest at 72 h after CIDR removal (78.57%, 76.47% and 68.42%, respectively; P<0.05). Diameter of first POF on day 0 to day 9 did not differ among treatment groups (P>0.05). Female goats in T3 had greater growth rate of POF after CIDR removal to first ovulation than T1 and T2 (0.57 ± 0.04 mm/day vs. 0.41 ± 0.04 mm/day and 0.39 ± 0.03 mm/day, respectively; P>0.05). The plasma P4 concentrations during CIDR insert (> 1 ng/ml) and after CIDR removal (< 1 ng/ml) did not differ among treatment groups (P>0.05). In the results of experiment 2, the proportion of goat exhibiting estrus, pregnancy rate, and kidding rate did not differ among treatment groups (P>0.05). However, prolificacy and litter size were the greatest in female goats receiving P4 + PGF + PMSG + 2GnRH program compared with P4 + PGF + PMSG + GnRH program (154.10% vs. 143.55% and 1.72 ± 0.094 kids/doe vs. 1.44 ± 0.075 kids/doe respectively; P<0.05). In addition, litter size proportion for single in female goats receiving P4 + PGF + PMSG + GnRH program was greater than female goats receiving P4 + PGF + PMSG + 2GnRH program (61.29% vs. 42.62%; P<0.05). Number of total follicles (< 2.0 to > 4.0 mm) in female goats receiving P4 + PGF + PMSG + 2GnRH program was greater than P4 + PGF + PMSG + GnRH program (3.08 ± 0.08 follicles vs. 2.82 ± 0.09 follicles; P<0.05). In both groups, percentage of the number of superficial cells in exhibited estrus goats was higher than anestrus goats (56.49 ± 0.82% vs. 47.78 ± 2.19%; P<0.05) and the plasma estradiol concentrations in exhibited estrous goats was higher than anestrus goats (29.21 ± 2.77 pg/ml vs. 17.00 ± 2.44 pg/ml; P<0.05). In conclusion, these results showed a beneficial effect of GnRH in the short-term progesterone-based protocol for inducing ovulation and the use of GnRH at initiation of protocol has a positive effect on the development of follicles and increasing the number of kids. Besides, a high proportion of at the day of the FTAI associated with estrous expression in female goats.