Estrous and ovulatory responses following cervical artificial insemination in Thai-native goats given a new or once-used controlled internal drug release with human chorionic gonadotropin

Periovulatory Hormonal Profiles after Estrus Induction and Conception Rate by Fixed-Time AI in Payoya Goats during the Anestrous Season

Simple Summary

Standardized induction and synchronization treatments and AI timing are used in goats, despite the fact that physiological differences can be linked to the breed, which could compromise the achievement of the AI programs in autochthonous breeds. However, few, if any, studies have been carried out to explore the reproductive physiology in the autochthonous breeds, in contrast to the commercial breeds. We studied the periovulatory hormone-release in Payoya goats, an autochthonous, endangered Spanish breed, and some differences were detected between the pregnant and non-pregnant goats. We observed a lower LH peak in those goats that failed to get pregnant, whilst other periovulatory hormones showed a similar release pattern in both groups. The results suggest that the LH peak should be favored to increase the success of fixed-time artificial insemination programs, and further studies should be conducted to understand the cause of this diminished LH release during the preovulatory surge.

Abstract

Sexual activity in domestic goats is positively influenced by reducing the photoperiod. Various protocols have therefore been developed in goats for the induction and synchronization of estrus during those months in which their sexual activity is reduced. The present observational study evaluates the periovulatory hormonal profile in Payoya goats (n = 24), during a non-favorable photoperiod (i.e., spring), being treated for estrus induction. The treatment comprised the vaginal insertion of sponges impregnated with progestogen (fluorogestone acetate, FGA), together with cloprostenol and equine chorionic gonadotrophin (eCG), 48 h before the end of the treatment. When the treatment ended, the plasma concentrations of the LH, FSH, progesterone and estradiol were determined. The goats were inseminated 46 h after the sponge withdrawal, and a pregnancy diagnosis was carried out 40–45 days after the insemination. Various parameters were monitored, such as the peaks of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and estradiol, and their respective intervals, in reference to the time of the sponge withdrawal. The conception rate was 62.5%, and the kidding rate was 50%. The results record the hormonal release pattern after the estrus synchronization treatment based on the FGA, and the differences between the pregnant and non-pregnant goats. The findings suggest that the LH peak produced after the estrus synchronization treatment, both in terms of the amplitude and the time of increment, is involved in the reproductive failure detected.

Effects of FSH treatment and withdrawal during proestrus on uterine proliferation and steroid hormone receptor expression in beef heifers

To determine the effects of Follicle Stimulating Hormone (FSH) treatment and subsequent withdrawal on uterine proliferation and estrogen receptor (ESR), Brahman crossbred heifers (n = 12) were twice daily injected with FSH (4, 3, and 2 mg/injection) on Days 17-19 of the estrous cycle (FSH 3 days) and (4 and 3 mg/injection) on Days 17-18 (FSH 2 days) and withdrawal with saline on Day 19 and (4 mg/injection) on Day 17 (FSH 1 day) and withdrawal with saline on Days 18-19. Uterine tissue was subjectively collected on Day 20 and microscopically classified to four regions: endometrial stroma (ES), surface endometrial gland (EG), deep endometrial gland (DG), and myometrium (Myo). The cell proliferation marker, Ki-67, was quantified as labeling index (LI) in uterine regions, and tissues were immunostained to detect ESR2 followed by image analysis. The LI of ES, EG, and DG was greater (P = 0.0018, P = 0.0005, and P = 0.0103; respectively) in heifers received FSH for 3 days. The expression of ESR2 protein on ES and EG was greatest (P < 0.0001 and P = 0.0036, respectively) in FSH 3 days-treated group. Thus, FSH administration during proestrus stimulates uterine cell proliferation, and ESR2 expressions are affected by FSH during proestrus and differentially distributed in the uterine regions.

The stimulatory effect of subluteal progesterone environment on the superovulatory response of passive immunization against inhibin in goats

The objective of the current study was to investigate the effect of subluteal progesterone environment on the efficacy of the ovarian responses in goats passively immunized against endogenous inhibin. Twelve cycling female Shiba goats were synchronized using two doses of prostaglandin F2α 11 days apart. After detection of ovulation (D0, by ultrasonography), goats were randomly assigned into 2 groups: (1) Subluteal P4 group (SLP; n = 6), treated with a previously once-used controlled intravaginal progesterone-releasing device (ou-CIDR) intravaginal from D 6 to D 12 concurrently with a luteolytic dose of PGF2α at D6 (2) Normal Luteal P4 group (NLP; n = 6), had neither ou-CIDR nor PGF2α. In both groups, goats were treated with an intravenous injection of 10 ml of inhibin antiserum at D10. After that, another luteolytic dose of PGF2α was administrated to goats in both groups at D12, and withdrawal of ou-CIDR in the SLP group. Detection of estrous behavior was checked again 24 h following PGF2α administration and or ou-CIDR withdrawal at 8 h intervals with a teaser buck. The follicle populations ≥4 mm in each goat were monitored through transrectal ultrasonography daily from 1 day after inhibin antiserum administration (0 h) and continued until ovulation had been detected (disappearance of large dominant follicles by ultrasonography). In addition, a repeated ultrasonographic scanning was performed 7 days after ovulation, and the ovulation rate had been estimated by counting the number of observed corpora lutea by ultrasonography. Blood samples were collected for measurement of plasma circulating inhibin binding activity, FSH, LH, estradiol (E2), and progesterone (P4) in both groups. Results revealed significant increases in maximum diameter of the preovulatory follicles (5.92 ± 0.17 mm vs 5.31 ± 0.26 mm; P < 0.05), and the mean maximum number of follicles ≥ 4 mm in diameter (18.45 ± 3.40 vs 12.15 ± 6.21; P < 0.05) in the SLP group compared with that of the NPL group. No significant differences were observed between both groups in term of inhibin binding activity %, and FSH. Following immunization, significant increases in the concentrations of circulating LH (at 72 h) and E2 (from 48 to 84 h) were noted in the SLP group as compared with the values obtained from the goats in the NLP group. Moreover, significant increases in ovulation rate (13.85 ± 1.40 vs 5.67 ± 2.10; P < 0.01) and subsequent P4 concentrations (from 192 to 288 h) were found in the SLP group as against those of the NLP group. In conclusion, maintaining a subluteal P4 environment concurrently with passive immunization against endogenous inhibin may improve the superovulatory response in female Shiba goats.

Assessment of caprine corpora lutea growth, progesterone concentration, and eNOS expression: effect of a compensatory gain model

The experiment was conducted to evaluate corpus luteum (CL) growth, progesterone (P4) concentration, and endothelial nitric oxide synthase (eNOS) expression in nutrient stair-step fed goats. Female goats (n = 32) that exhibited at least 2, normal, consecutive estrous cycles were randomly assigned to either the control or stair-step fed group. In the control group, goats were fed ad libitum (100% of nutrient requirement for goats). The goats in the stair-step group were fed 70% of the control consumption for the first 42 d and 130% for the later 42 d during 4 consecutive estrous cycles (84 d). Blood and luteal samples were collected on days 3, 8, 13, and 18 of the estrous cycle to determine concentration of glucose, insulin, P4, luteal growth, and eNOS expression. Luteal growth was determined using fresh CL weight, DNA content, DNA and protein concentrations, and cell proliferation (labeling index of Ki-67). During realimentation phase at 4 h, glucose and insulin concentrations were greater (P < 0.05) in stair-step fed goat than those in control goats. Fresh CL weight, DNA content, protein concentrations, and labeling index of Ki67 on day 8 of the estrous cycle in the stair-step group were greater (P < 0.05) than that in the control group. Protein for eNOS was located in the capillaries of CL throughout of the estrous cycle in both groups. Greater serum P4 concentrations and eNOS protein (P < 0.05) were observed in the stair-step fed goats on day 3 (1.83 ng/mL and 6.79%) compared with the control goats (0.98 ng/mL and 6.02%) and on day 8 (5.15 ng/mL and 7.88%) compared with the control goats (4.54 ng/mL and 7.07%). These data demonstrate that luteal growth, progesterone concentration, and eNOS protein were partially affected by nutrient compensatory gain in goats.