Effects of treatment with a prostaglandin analogue on developmental dynamics and functionality of induced corpora lutea in goats

Ovarian Dynamics and Changes in Estradiol-17β and Progesterone Relationship with Standing Estrus, Preovulatory Follicles, and Ovulation Using Single Prostaglandin F2α Injection in Barbari Goats

The purpose of the present research was to define ovarian follicular dynamics and plasma endocrine profiles in response to a single PGF2α injection, administered indiscriminately during the breeding season of Barbari goats. Ovarian dynamics were observed at every 12 h interval by using B mode ultrasonography, blood samples for hormonal analysis such as estradiol 17β and progesterone were collected at every 12 h interval, and bucks with aprons were used to identify standing estrus at every 6 h interval. Relative to PGF2α, the start of standing estrus and ovulation differ (p < 0.05) between early- (n = 7), intermediate- (n = 6), and late-responding (n = 6) goats. The highest plasma level of estradiol 17β was detected 12 h prior to ovulation. The average diameter of the ovulatory follicle and length of standing estrus were comparable (p > 0.05) between the goats. The corpus luteum degenerated more quickly (p < 0.05) in early- than intermediate- and late-responding goats. Dominant follicle diameter and estradiol 17β concentration also differ (p < 0.05) among groups. Although the plasma level of progesterone did not vary (p = 0.065), the variation in progesterone concentration with time differed (p < 0.05) amongst the goats. As a result, this research indirectly reveals that the beginning of standing estrus, end of estrus, and ovulation after PGF2α might fluctuate in Barbari goats because of follicular and hormonal dynamics during the luteal phase.

Effects of d-cloprostenol administrations with 7.5 and 11.5-day intervals between administrations on pregnancy rates after artificial insemination in estrous cyclic dairy goats

This study was conducted to evaluate effects of two administrations of d-cloprostenol at different intervals to synchronize the time of estrus and ovulation among estrous cyclic goats. In Experiment 1, 32 does were treated with 30 μg d-cloprostenol at 7.5 (T7.5, n = 16) or 11.5-day (T11.5, n = 16) intervals. In Experiment 2, the same treatments were administered and there was AI of the does (T7.5, n = 40 and T11.5, n = 38). In Experiment 1, ultrasonic assessments of ovaries were conducted at the time of the second administration of d-cloprostenol, every 12 h until detection of ovulation, and 7 days after estrous onset to detect the corpora lutea, as well as for pregnancy diagnosis 40 days after AI. In Experiment 1, the estrous response (90.6%, 29/32) was similar (P > 0.05) in both groups. Diameter of the largest follicle at the time of administration of the second dose was larger (P = 0.01) in the T7.5 than T11.5 group (7.0 compared with 5.7 mm), while the values for ovarian variables were similar (P > 0.05). In Experiment 2, the greatest (P < 0.001) synchrony in timing of initiation of estrus in does (T7.5 = 83.3% and T11.5 = 50.0%) occurred after the second day (36-48 h). The pregnancy rate tended (P = 0.0836) to be greater for does in the T7.5 (71.4%, 40/56) than T11.5 (55.6%, 30/54) group. With use of both protocols, there were acceptable estrous synchronization and pregnancy rates in estrous cyclic dairy goats.

Suppression of COX-2 mRNA abundance in in vitro cultured goat (Capra hircus) endometrial cells by RNA interference and effect on PGF2-α and PGE2 concentrations

Cyclooxygenase-2 (COX-2) has important functions in the synthesis and release of endometrial prostaglandin F2α (PGF2α). Excessive production of COX-2 leads to an increase in endometrial PGF2α synthesis and subsequently causes luteolysis and early embryonic mortality. The aim of this study was to investigate in goats the effects of COX-2 small interference RNA (siRNA) on COX-2 mRNA abundance and the secretion of PGF2α and PGE2 in goat endometrial cells. Endometrial cells isolated from goat uteri were cultured at 38.5 °C and 5% CO₂. The cells were treated with different concentrations (0, 10, 25, 50, 100, 250, 500, 750 and 1000 nM per well) of three different COX-2 siRNAs at confluency for 24 h. At 24 h post culture, COX-2 mRNA abundance was quantified using qPCR and PGF2α and PGE2 concentrations were quantified in the culture medium. There was a lesser relative abundance of COX-2 mRNA in endometrial cells at 100 to 1000 nM siRNA. The greatest extent of abundance suppression, however, was observed with 1000 nM siRNA. Transfection of COX-2 siRNA (1000 nM) to endometrial cells suppressed the COX-2 mRNA abundance by 77%, 82%, and 84% with siRNA 1, 2, 3, respectively. Furthermore, with COX-2 siRNA transfected cells, there was a lesser (P < 0.05) PGF2α concentration than in cells not transfected, whereas PGE₂ secretion was not affected. The results of the study provide evidence that COX-2 siRNA used in this study suppresses COX-2 mRNA abundance and PGF2α secretion but there was no association between PGE2 concentrations and COX-2 mRNA abundance in goat endometrial epithelial cells.

Reproductive parameters of dairy goats submitted to estrus synchronization with prostaglandin F2α associated or not to hCG at estrous onset

The objective of this study was to evaluate the efficiency of two doses of PGF associated or not to hCG on the associated reproductive parameters in dairy goats. A total of 29 goats received two doses of 30µg d-cloprostenol latero-vulvar at a 10 day intervals (Day 1 and Day 10). The does were allocated according to body weight and body condition score into two treatments, to receive hCG (250IU) or saline at estrus onset. After the second dose of PGF, estrus was monitored and ultrasound exams were performed twice daily. All does were inseminated 16h after estrus onset. Blood collection was performed every day for progesterone assay. The use of hCG at estrus onset did not affect any studied parameter and therefore the data were pooled. Estrous response rate was similar (P>0.05) after the first (75.9%, 22/29) and the second dose of PGF (79.3%, 23/29). The interval between the administration of PGF and estrus onset was greater (P<0.05) after Day 1 (75.8±53.9h) than Day 10 (47.7±10.1 h). Estrus duration was superior (P < 0.05) after Day 1 (35.4±15.9h) to Day 10 (26.8±15.0h). Ovulation rate was 79.3% (23/29) after the second dose of PGF. No differences (P>0.05) between both experimental groups were detected in the following parameters, averaging: the interval from the second dose administration to the ovulation (86.6±11.4h), interval from estrus to ovulation (39.9±12.3 h), diameter of largest follicle (7.2±1.4) and number of ovulations (1.8±0.6). At Day 1, 52.4% (11/21) of does presented progesterone concentrations <1ng/mL. At Day 10, 100% of the animals presented concentrations >1ng/mL. The results of the present study indicate that estrus can be efficiently synchronized in dairy goats with the use of two doses of PGF at a 10 day interval. Further research should be done evaluating hCG use in different doses or moments of administration.

Glucogenic supply increases oocyte developmental competence in sheep

The present study aimed to determine the influence of a glucogenic supply on oocyte developmental competence. Oestrous cycles were synchronised in 22 Sarda ewes by the insertion (Day 0) of one intravaginal progestagen-impregnated sponge that was removed after 6 days. After removal, the ewes were randomly allocated into two experimental groups (treated and control ewes) and, from Day 7 to Day 11, treated ewes received oral administration of a glucogenic mixture, whereas control animals received water. Follicular development was stimulated by FSH administration from Days 8 to 10. Glucose metabolism was assessed from Days 7 to 11, whilst follicle and corpus luteum growth dynamics and functionality were evaluated between Days 6 and 11. At Day 11 ovaries were collected and processed for in vitro embryo production. Glucogenic treatment increased both the plasma levels of glucose, progesterone, oestradiol and the number of 2-3-mm follicles (P < 0.05). Higher fertilisation and blastocyst rates (P < 0.05) were obtained after IVM of oocytes recovered from treated ewes compared with control ones. In conclusion, glucogenic treatment modifies follicle and corpus luteum functionality and improves oocyte quality, as evaluated by in vitro developmental kinetics and blastocyst output.

Ultrasonographic imaging in small ruminant reproduction

CONTENTS

Ultrasonography is a simple, reliable and non-invasive imaging technique without secondary effects. Application of ultrasonography in veterinary practice, and specifically in small ruminants, has developed to become the most efficient diagnostic tool for managing reproduction. The objectives of current revision are to offer an overview, after a short reminder of equipment and techniques for imaging genitalia in small ruminants, of the uses and utility of ultrasonography for the evaluation of physiological and pathological conditions in males and females and for the application of assisted reproductive technologies.