Patterns of oviducal motility in the cow during the oestrous cycle

Microtransducers sensitive to changes in internal diameter were chronically implanted in the oviducts of 5 dairy cows. Motility patterns were recorded throughout 9 oestrous cycles. Cyclic variations in patterns of motility were observed and compared with circulating concentrations of plasma progesterone. Luteal-phase motility patterns were of low amplitude and frequency. The frequency and amplitude of motility increased 3-5 days before behavioural oestrus. This activity consisted primarily of longitudinal muscle contractions, with an interspacing of circular muscle activity occurring during oestrus. Patterns of activity after oestrus were similar to those before oestrus, with activity decreasing 3-5 days after oestrus. Transducers implanted bilaterally in 2 animals permitted observation of asynchronous patterns between right and left oviducts. Preliminary data suggested a higher level of activity in the oviduct ipsilateral to the active ovary. These variations may be due to a local effect, possibly mediated by the functional ovary or the ovum.     

Changes in phospholipids, cholesterol and protein content of oviduct fluid of cows during the oestrous cycle

The oviducts of 4 cows were cannulated and oviduct fluid was collected daily from the exteriorized cannulas for a total of 5 oestrous cycles. Daily serum samples were assayed for oestradiol-17 beta and progesterone to monitor the oestrous cycle. Data for each cycle were compared for oviduct fluid collected during the non-luteal phase (serum progesterone less than or equal to 1.5 ng/ml) and the luteal phase (serum progesterone greater than 1.5 ng/ml). During the non-luteal phase oviduct fluid volume was higher and the osmolality was lower than during the luteal phase. Total protein, cholesterol and phospholipid secreted daily was greater during the non-luteal phase. Cholesterol and protein concentrations were generally lower during the non-luteal phase, but phospholipid concentrations were generally higher. About 40% of the phospholipid in oviduct fluid was phosphatidylcholine and lysophosphatidylcholine, while phosphatidylinositol and lysophosphatidylinositol accounted for 20%. The ratio of 1-acyl-phospholipid to diacylphospholipid increased during the non-luteal phase. An increased cholesterol to phospholipid ratio, and a decreased cholesterol to protein ratio in oviduct fluid also were associated with the non-luteal phase. Changes in the lipid composition of oviduct fluid during the oestrous cycle may play a role in the preparation of gametes for fertilization.     

Local distributions of oviductal estradiol, progesterone, prostaglandins, oxytocin and endothelin-1 in the cyclic cow

The cyclic patterns of hormones which regulate the activity of the oviduct in the cow have not been adequately reported. We studied progesterone (P4), estradiol 17 beta (E2), prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), oxytocin (OT) and endothelin-1 (ET-1) concentrations in the cow oviduct. Reproductive tracts from cyclic Holstein cows in the follicular phase (n = 5), post ovulation phase (n = 5) and luteal phase (n = 5) were collected at a slaughterhouse. Oviducts were separated from the uterus, the lumen vas washed with physiological saline, and the enveloping connective tissues were removed. The fimbria was then separated at first and then the rest was divided into 2 parts of equal length (proximal and distal). After extraction, levels of different hormones in the tissues were measured using double antibody enzyme immunoassays (EIAs). There were no differences in any hormone concentration between the 3 parts of the oviduct at any stage of the estrous cycle. The highest concentration of oviductal P4 was observed during the luteal phase and in the oviduct ipsilateral to the functioning CL. Oviductal OT was unchanged throughout the cycle. The highest E2 concentration was observed during the follicular phase in the oviduct ipsilateral to the dominant follicle. The oviduct ipsilateral to the dominant follicle during the follicular phase and ipsilateral to the ovulation site post ovulation showed higher levels of PGE2, PGF2 alpha and ET-1 than those on the contralateral side or during the luteal phase. The highest PGE2 was observed in the oviduct ipsilateral to the ovulation site during the post ovulation phase. The results suggest that the ovarian products (P4, OT and E2) and the local oviductal products (PGE2, PGF2 alpha, and ET-1) may synergistically control oviductal contraction for optimal embryo transport during the periovulatory period, and provide further evidence for the local delivery of ovarian steroids to the adjacent reproductive tract.     

Gamma-aminobutyric acid in the genital tract of the rat during the oestrous cycle

The highest values of gamma-aminobutyric acid (GABA) in the genital tract of the rat at different stages of the oestrous cycle were found in the oviduct (3.5-7 micrograms/mg protein) and the lowest in the ovary (50-100 ng/mg protein). The values for uterus and vagina ranged between 80 and 150 ng/mg protein. GABA (10-30 ng/microliter) was also found in fluid in the ovarian bursa. At 11:00 h, on the day of oestrus, GABA content increased in the ovaries but values in the oviducts were maximal at 11:00 h on the day of pro-oestrus. Variations in GABA content of the vagina were also found. Uterine cervix or uterine horn showed no changes during the oestrous cycle. The GABA content was not uniform throughout the oviduct: the highest values were found in the portion next to the ovary. At 10 days after removal of the right oviduct, GABA values in the ovary and ovarian bursa fluid decreased on the operated side. At 1 month after surgery, the values in ovary were normal but the values in ovarian bursa fluid were still low, suggesting that the source of ovarian GABA was not the oviduct. The variations observed in the present paper suggest an involvement of GABA in reproductive physiology.     

Oestradiol and progesterone receptors in the pig oviduct during the oestrous cycle

The concentrations of the tissue receptors for oestradiol (E) and progesterone (P) in the porcine oviduct at different stages on the oestrous cycle have been investigated by in vitro binding and exchange methods. Both hormones bound to specific cytoplasmic (Rc) and nuclear (Rn) receptor proteins with high affinity. The concentrations of ERc and ERn were two-fold higher in the ampulla as compared to the isthmus. The amount of ERc in the isthmic portion of the oviduct did not vary throughout the oestrous cycle. However, the ampullar ERc concentrations increased during prooestrus, showed a maximum at standing oestrus, thereafter decreasing. Significant variations in the amount of oviductal ERn were observed. Despite the differences in ERn amounts between segments, the concentration of ERn increased significantly during late prooestrus, attaining a three-fold elevation and remaining elevated during the period of standing oestrous and early luteal phase (days 3-4), thereafter returning to basal levels. No significant variations in the amount of isthmic PRc were found throughout the period studied. The ampulla, however, showed a significant increase in PRc concentrations during standing oestrus, thereafter decreasing. The concentrations of PRn in isthmus and ampulla were of about the same magnitude and varied significantly during the oestrous cycle, increasing in concentration from standing oestrous onwards. The temporal relationships between the variations in levels of oestradiol and progesterone receptors in oviductal tissues and those of the circulating plasma levels were established. The data obtained in this study suggest a relationship between the changes in the levels of oestradiol and progesterone oviductal binding during the first days of the oestrous cycle, and the gamete and embryo transport throughout the oviduct in the porcine species.     

Immediate and delayed effects of heat stress on follicular development and its association with plasma FSH and inhibin concentration in cows

The aim of this study was to characterize the immediate effects of heat stress on plasma FSH and inhibin concentrations, and its involvement in follicular dynamics during a complete oestrous cycle, and to examine a possible delayed effect of heat stress on follicular development. Holstein dairy cows were oestrous synchronized and randomly assigned to either cooled (n = 7) or heat-stressed (n = 6) treatment groups. During a complete oestrous cycle, control cows, which were cooled, maintained normothermia, whereas heat-stressed cows, which were exposed to direct solar radiation, developed hyperthermia. At the end of this oestrous cycle (treated cycle), both groups were cooled and maintained normothermia for the first 10 days of the subsequent oestrous cycle. Throughout this period, follicular development was examined by ultrasonography, and plasma samples were collected. During the second follicular wave of the treated oestrous cycle, a significantly larger cohort of medium sized follicles (6-9 mm) was found in heat-stressed cows than in cooled cows (P < 0.05). The enhanced growth of follicles in this wave in heat-stressed cows was associated with a higher plasma FSH increase which lasted 4 more days (days 8-13 of the oestrous cycle; P < 0.05), and coincided with a decrease in the plasma concentration of immunoreactive inhibin (days 5-18 of the oestrous cycle; P < 0.05). During the follicular phase (days 17-20 of the treated cycle), heat-stressed cows showed an increase in the number of large follicles (>/= 10 mm), and the preovulatory plasma FSH surge was significantly higher in heat-stressed cows than in cooled cows (P < 0.01). The effect of heat stress was also observed during the first follicular wave of the subsequent cycle: the postovulatory plasma FSH concentration was higher (P < 0.01), but fewer medium follicles developed, and the first follicular wave decreased at a slower rate in previously heat-stressed cows than in cooled cows (0.40 and 0.71 follicles per day, respectively). This study shows both immediate and delayed effects of heat stress on follicular dynamics, which were associated with high FSH and low inhibin concentrations in plasma. These alterations may have physiological significance that could be associated with low fertility of cattle during the summer and autumn.     

Oviductal morphology in relation to hormonal levels in the snapping turtle, Chelydra serpentina

Microscopic and in situ visual observations were used to relate circulating hormone levels to morphological changes in the oviduct of the snapping turtle Chelydra serpentina throughout the ovarian cycle. Increase in levels of progesterone (P), estradiol (E2) and testosterone (T) levels coincide with an increase in number and growth of endometrial glands, luminal epithelial cells and secretory droplets throughout the oviduct. Testosterone and estradiol levels rose significantly (P < 0.05) after the May-June period and remained high throughout the rest of the summer. Progesterone levels remained stable throughout the summer, with a brief decline in July due to luteolysis. Hormonal values declined significantly (P < 0.001) at the end of the ovarian cycle in the fall. In situ visual observation of fresh oviducts at different stages of gravidity in recently ovulated turtles revealed that proteinaceous like components from the endometrial glands were released into the lumen to form fibers. The morphological features of the oviduct remained active throughout the summer months even though the snapping turtle is a monoclutch species which deposits all the eggs in late-May to mid-June. The high steroid levels correlate with and may be responsible for the secretory activity present throughout the summer and their decline correlates with change to low secretory activity in the fall. Calcium deposition accompanied by morphological changes in luminal cells are suggestive of secretory activity. In the egg-bearing turtles, uterine Ca2+ concentrations measured by flame atomic absorption spectrophotometry revealed significantly higher Ca2+ concentrations (P < 0.001) in eggs with soft shell than eggs without shell. There was a significant increase in calcium granules and proteinaceous fibers in luminal surface of the uterus during the period of eggshelling. This supports the fact that in the snapping turtle like in other reptiles, eggshelling process occurs in the uterus.     

Comparison of an oestrus synchronisation protocol with oestradiol benzoate and PGF2alpha and insemination at detected oestrus to a timed insemination protocol (Ovsynch) on reproductive performance of lactating dairy cows

A total of 226 out of 245 postpartum lactating dairy cows in a commercial dairy farm were allocated to two groups of oestrous synchronisation protocols in order to evaluate reproductive performance. One group was treated with oestradiol benzoate (ODB) and PGF2alpha on day 10 of the oestrous cycle with insemination at the detected oestrus, the second group underwent the Ovsynch (OVS) protocol (GnRH + PGF2alpha + GnRH) with timed AI. Pregnancy was diagnosed by ultrasonography on day 28 after AI and confirmed by rectal palpation on day 45. A higher (P < 0.001) proportion of cows in OVS (100%) were inseminated within (19.2 +/- 3.8 h) following the second GnRH injection than those of cows in EPE (ODB + PGF2alpha + ODB) (70.6%) inseminated at the detected oestrus within (35.6 +/- 5.2 h) following the second ODB injection. Pregnancy rates for the first AI at day 28 (64.0 +/- 4.6, 62.4 +/- 5.5%) and at day 45 post-insemination (40.4 +/- 4.7, 40.0 +/- 5.6%) for OVS and EPE cows respectively, did not differ between the two treatments, whereas, the overall pregnancy rates tended to be higher (P < 0.08) for the OVS (85.1 +/- 3.8%) cows than the EPE cows (74.1 +/- 4.5%). No differences were observed in pregnancy rates for first AI and overall up to fourth AI between primiparous (34.7 +/- 5.8 and 85.3 +/- 4.7%) and multiparous cows (43.5 +/- 4.5 and 77.4 +/- 3.6%). Days open for pregnant cows tended to be lower (P < 0.08) for OVS (76.2 +/- 3) than for EPE cows (84.7 +/- 4), while days open were higher (P < 0.05) in primiparous cows (85.3 +/- 4) than in multiparous cows (75.6 +/- 3). The results indicate that pregnancy rates for first AI were similar, but overall pregnancy rates up to the fourth AI tended to be higher for OVS than EPE cows, while days open was tended to be lower for OVS than EPE cows.     

Motility of the oviduct and uterus of the cow during the oestrous cycle.

Recordings of electrical activity of the oviduct and uterus were obtained during three oestrous cycles in cows fitted with an extra-cellular multi-electrode assembly. The stages of the cycle were identified by the appearance of the cervico-vaginal secretions and changes in the peripheral plasma level of progesterone were determined by radioimmunoassay. A gradual transition from local non-propagating electrical activity to propagating electrical activity with increase in the duration of contractions and then of their amplitude occurred 48 hr before the onset of oestrus. The transition coincided with a rapid decrease in progesterone level from 5 to 10 ng/ml to less than 0-1 to 0-4 ng/ml. This phenomenon was recorded from all uterine electrode sites, but was most marked at the uterotubal junction. Two days before oestrus, trains of potentials and bursts of activity became progressively grouped, apparently randomly, into prolonged phases in the distal portion of the oviduct and over the entire myometrium. During oestrus, the phases of activity became synchronized at these sites and both their amplitude and frequency reached a maximum. The strength but not the frequency of the phases diminished progressively 3 days after oestrus, followed by relative inactivity. The last remaining zone of activity was the uterotubal junction. During oestrus, the activities of the oviduct and the uterus were modified by oxytocin and adrenaline, the effect of the former being more marked on the uterus and that of the latter on the oviduct.     

The corpora lutea proangiogenic state of VEGF system components is turned to antiangiogenic at the later phase of the oestrous cycle in cows

Blood vessel expansion and reduction in the corpus luteum (CL) is regulated by the vascular endothelial growth factor (VEGF) system and linked to the maintenance of the CL. The VEGF system has both angiogenic and antiangiogenic ligands and receptors. Our objective was to evaluate the relationship between the mRNA expression of angiogenic and antiangiogenic members of the VEGF system in the CL, throughout the luteal phase of the oestrous cycle in cows. The CL of 18 cows were collected by transvaginal surgery on days 4, 6, 9, 12, 15 and 18 of the oestrous cycle and the mRNA expression of VEGF system components was evaluated by quantitative real-time PCR. The mRNA expression of VEGF ligands and receptors increased (P<0.05) from the early- and mid-luteal phase (days 4 to 12) reaching its maximum expression on day 15 of the cycle. We found no expression of VEGF164b throughout the cycle. Expression of sVEGFR1 did not change during the oestrous cycle and exceeded that of the VEGFR1 by 100 times. Nonetheless, as VEGFR1 increased, the relationship between the soluble and membrane receptor decreased (P<0.01). In contrast, the expression of VEGFR2 was higher than that of its soluble isoform for all days studied, however, the ratio between the membrane-bound and its soluble counterpart decreased continuously throughout the cycle (P<0.01). Our results show that the expression levels for VEGF ligands, receptors and their antagonistic counterparts are adjusted during CL development and regression, to upregulate angiogenesis early in the oestrous cycle and restrict it at the time of luteolysis.     

The concentrations of catecholamines and oxytocin receptors in the oviduct and its contractile activity in cows during the estrous cycle

In vitro experiments on oviducts of cyclic cows were undertaken to study: (1) the content of dopamine (DA), noradrenaline (NA) and adrenaline (A) in infundibulum, ampulla and isthmus, (2) the concentration of oxytocin receptors (OTR) in oviductal tissues and (3) the motility of ampulla and isthmus. Changes of DA content were observed in the infundibulum and the ampulla with maximal values occurring on Days 6-10 of the estrous cycle. The mean NA content was greatest in infundibulum相似文献   

Constitutive expression of heat shock proteins hsp25 and hsp70 in the rat oviduct during neonatal development, the oestrous cycle and early pregnancy

Certain heat shock proteins are regulated by steroid hormones and are associated with oestrogen receptor function in reproductive tissues, indicating that these proteins have a role during implantation, decidualization and placentation. In the present study, the expression of hsp25, hsp70 and oestrogen receptor alpha were examined by immunohistochemistry in oviducts from rats during neonatal development, the oestrous cycle and during early pregnancy. Oestrogen receptor alpha was the first protein observed in the neonatal oviduct, and its expression preceded that of hsp70 and hsp25. Although these heat shock proteins have been associated with the oestrogen receptor, this study showed that during early development of the oviduct, the receptor protein was not associated with the concomitant expression of hsp25 and hsp70. However, these heat shock proteins were expressed when oviductal cells became differentiated. In the adult oviduct, hsp70 was more abundant than hsp25, moreover, there were no significant modifications in expression of hsp25 during the oestrous cycle. In contrast, the expression of hsp70 was significantly higher in epithelial cells during dioestrus, when the maximum amount of oestrogen receptor alpha was also observed. Therefore, the present study shows that hsp70, but not hsp25, is an oviductal protein modulated by the oestrous cycle and that it is a protein marker for specific phases of the oestrous cycle. In addition, hsp70 was more responsive to the hormonal changes in the infundibulum and ampullar regions of the oviduct. During early pregnancy, hsp25 expression was downregulated (unlike in the endometrium), whereas hsp70 was relatively abundant in the oviduct. hsp70 was observed in all functional segments of the oviduct during pregnancy, indicating that in the oviduct, this protein is modulated by oestrogens and progesterone and possibly by other pregnancy-related hormones.     

The sow endometrium at different stages of the oestrous cycle: studies on the distribution of CD2, CD4, CD8 and MHC class II expressing cells

The aim of this study was to investigate the distribution of CD2+, CD4+, CD8+ lymphocyte subpopulations and MHC class II expressing cells in the sow endometrium throughout the oestrous cycle. Fifteen crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire), with an average parity number of 3.4+/-0.7 (mean+/-S.D.) were used. Uterine samples from the mesometrial side of both horns, taken immediately after slaughter at late dioestrus (day 17, n=3), prooestrus (day 19, n=3), oestrus (day 1, n=3), early dioestrus (day 4, n=3) and dioestrus (days 11-12, n=3), were stored in a freezer at -70 degrees C until analysed by immunohistochemistry with an avidin-biotin peroxidase method using monoclonal antibodies to lymphocyte subpopulations and MHC class II molecules. The surface and glandular epithelium as well as connective tissue layers in subepithelial and glandular areas were examined by light microscopy.For the T lymphocyte subpopulations, all oestrous cycle stages and different tissue layers taken together, the most commonly observed cell type was CD2+ cells. The largest number of CD2+ cells within the surface and glandular epithelium were observed at oestrus and early dioestrus. In the surface epithelium, a larger number of CD8+ cells compared with CD4+ cells were observed and no CD4+ cells were found within the glandular epithelium at any stage of the oestrous cycle.In the subepithelial and glandular connective tissue layers, during the oestrus cycle stages, a larger number of CD4+ cells compared with CD8+ cells were found.Endothelial cells in the connective tissue generally expressed MHC class II. However, no obvious differences between oestrous cycle stages were observed. For other cells than endothelial cells, the result was as follows. In the surface epithelium, a large number of MHC class II expressing cells was observed at oestrus compared with the other stages. No MHC class II expressing cells were found at late dioestrus and dioestrus. MHC class II expressing cells were also found in the glandular epithelium, and in the subepithelial and glandular connective tissue layers during all oestrous cycle stages but with no significant differences between stages.In conclusion, the present study showed a variation in the distribution of T lymphocyte subpopulations (CD2+, CD4+ and CD8+) and MHC class II expressing cells in the sow endometrium during different stages of the oestrous cycle. Also a variation between different tissue layers was found. It is suggested that helper and cytotoxic function of the immune system have primary locations in different tissue layers of the endometrium.     

Gene expression patterns in anterior pituitary associated with quantitative measure of oestrous behaviour in dairy cows

Intensive selection for high milk yield in dairy cows has raised production levels substantially but at the cost of reduced fertility, which manifests in different ways including reduced expression of oestrous behaviour. The genomic regulation of oestrous behaviour in bovines remains largely unknown. Here, we aimed to identify and study those genes that were associated with oestrous behaviour among genes expressed in the bovine anterior pituitary either at the start of oestrous cycle or at the mid-cycle (around day 12 of cycle), or regardless of the phase of cycle. Oestrous behaviour was recorded in each of 28 primiparous cows from 30 days in milk onwards till the day of their sacrifice (between 77 and 139 days in milk) and quantified as heat scores. An average heat score value was calculated for each cow from heat scores observed during consecutive oestrous cycles excluding the cycle on the day of sacrifice. A microarray experiment was designed to measure gene expression in the anterior pituitary of these cows, 14 of which were sacrificed at the start of oestrous cycle (day 0) and 14 around day 12 of cycle (day 12). Gene expression was modelled as a function of the orthogonally transformed average heat score values using a Bayesian hierarchical mixed model on data from day 0 cows alone (analysis 1), day 12 cows alone (analysis 2) and the combined data from day 0 and day 12 cows (analysis 3). Genes whose expression patterns showed significant linear or non-linear relationships with average heat scores were identified in all three analyses (177, 142 and 118 genes, respectively). Gene ontology terms enriched among genes identified in analysis 1 revealed processes associated with expression of oestrous behaviour whereas the terms enriched among genes identified in analysis 2 and 3 were general processes which may facilitate proper expression of oestrous behaviour at the subsequent oestrus. Studying these genes will help to improve our understanding of the genomic regulation of oestrous behaviour, ultimately leading to better management strategies and tools to improve or monitor reproductive performance in bovines.     

Oestrogen-dependent expression of LH/hCG receptors in pig Fallopian tube and their role in relaxation of the oviduct.

The current studies investigated the concentration and distribution of LH receptors in the oviduct of ovariectomized gilts at various times after administration of oestradiol benzoate (10 micrograms kg-1 body weight) to determine whether LH participates in the regulation of oviductal contractions. Polyclonal antibodies to the LH receptor were used in immunocytochemical and western blot analyses of oviductal tissues. The mechanical activity of the isthmus and ampullar segments of oviduct, collected from 16 cyclic gilts, was recorded for 30 min after LH or hCG treatment. In the oviduct, there was little competition for receptor occupancy between hCG and pig FSH, bovine thyroid-stimulating hormone (TSH), pig growth hormone (GH) and pig prolactin (1.2, 0.1, 0.01 and < 0.001%, respectively) but pig LH could completely inhibit the binding of [125I]hCG. Oestradiol benzoate increased (P < 0.01) the number of LH binding sites in oviduct 24, 48 and 72 h (0.60 +/- 0.08, 1.62 +/- 0.15, 2.48 +/- 0.35 fmol mg-1 protein; n = 4 per treatment, respectively) after injection compared with the control gilts treated with corn oil (0.20 +/- 0.04 fmol mg-1 protein; n = 4). The affinity of oviductal LH/hCG binding sites (Ka) varied from 4.0 to 8.5 x 10(10) l mol-1 and was similar to that of luteal cell binding sites (6.1 x 10(10) l mol-1). Oestradiol benzoate also resulted in more intense LH receptor immunostaining of the tubal mucosal epithelium, smooth muscle cells and blood vessels as compared with controls. Western blotting has revealed that the pig oviduct, similar to the corpus luteum, contains 75, 48 and 45 kDa immunoreactive LH receptor proteins. Treatment with LH in vitro (100 ng ml-1) affected the contractility of oviduct. During the peri-ovulatory stage of the oestrous cycle, the amplitude, frequency and area under curve(s) of the isthmus decreased (P < 0.05), as did the frequency and area under curve (P < 0.05 and P < 0.01, respectively) of the ampulla (n = 4). The frequency and area under curve of the oviductal contractions were also significantly reduced during the early follicular phase of the oestrous cycle (P < 0.05). There was no effect of LH (or hCG) on the frequency and area under curve of the oviductal contractions during luteal stages of the oestrous cycle (n = 8). These data indicate that (1) the pig oviduct possesses immunoreactive and functional LH receptor, (2) oestradiol promotes the synthesis of LH receptor in the epithelium and smooth muscles, and (3) LH causes the relaxation of oviduct, especially during the peri-ovulatory stage of the oestrous cycle. In summary, the results of the present study indicate that LH can control oviductal contractions directly and may be partially responsible for the relaxation of isthmus during fertilization in pigs.     

Contractility of the ovarian vascular bed during the oestrous cycle and early pregnancy in gilts

The vasoconstrictor activity of the ovarian vascular bed in vitro was investigated during the oestrous cycle and early pregnancy. Gilts were killed during the follicular phase (Days 20 to +1; N = 5) or luteal phase (Days 11 to 13; N = 4) of the oestrous cycle, or on Day 13 of pregnancy (N = 5). Immediately before death, a sample of vena cava blood was obtained for determination of progesterone and oestrogen (oestrone and oestradiol-17 beta) concentrations. One ovary was removed, cannulated, perfused in vitro, and subjected to 10-min infusions of saline (vehicle control) and noradrenaline. Vasoconstriction was provoked by electrical stimulation at the end of each infusion. Ovaries from luteal-phase gilts exhibited greater (P less than 0.01) vasoconstriction than did ovaries from follicular-phase and pregnant gilts at the end of saline and noradrenaline infusions. The oestrogen to progesterone ratio was less (P less than 0.01) for luteal-phase and pregnant than for follicular-phase gilts. Vasoconstriction was negatively correlated (r = -0.99, P less than 0.01) with the oestrogen to progesterone ratio in systemic blood of gilts during the oestrous cycle but not during early pregnancy (r = +0.39, P greater than 0.10), possibly due to an effect of the conceptuses.     

Serum progesterone profiles of zebu cattle (Bos indicus) in relationship to conception and repeat breeding after artificial insemination

Sixty-four zebu cows, comprised mainly of Bunaji cattle aged between 3 and 7 years old, were involved in an intensive artificial insemination programme. The study was conducted during the breeding period (May-October), and cows were inseminated with freshly prepared Friesian semen when they stood to be mounted by the vasectomised bull or herdmates. Fertility was measured by serum progesterone (P(4)) concentrations and pregnancy diagnosis by rectal examination post-insemination. From the records of oestrus detection and P(4) profiles of cattle following breeding, 39 oestrous cycle lengths were classified into short, normal and long cycles. The mean duration for short, normal and long oestrous cycles were 15.6+/-2.0, 21.5+/-1.5 and 29.5+/-2.5 days, respectively. Mean inter-oestrus intervals between the treatment groups were not different. The percentage frequency distribution was 48.7% for normal oestrous cycles. The short oestrous cycle lengths of 11-17 days were observed in 12.8% of the cases, while 38.5% of the cases of oestrus returns had long luteal phases with oestrous cycle lengths of 26-32 days.Out of the 64 cows, 48.4% conceived to the first breeding while 18.8% conceived to the second breeding. Five and nine cows became acyclic after the first and second breeding, respectively, constituting 22. 0%. Cows that displayed irregular oestrous cycles (repeat breeders) constituted 10.9%. Average number of services per conception was 1.3. Serum P(4) is of practical value in monitoring ovarian activity in cattle and in the identification of acyclic and repeat breeder cows. Repeat breeder cows could be investigated by a combination of radioimmunoassay and clinical examination of the ovaries and reproductive tract. In cattle management, it is economical and profitable to diagnose pregnancy early after insemination so that cows which fail to conceive may be rebred.     

Comparison of the steroidogenic capacity of bovine follicular and luteal cells, and corpora lutea originating from dominant follicles of the first or second follicular wave

This study, compared the endocrine function of dominant follicles of the first and second follicular waves (DF1 and DF2, respectively) and the corpora lutea that were subsequently formed. In the experiments conducted in vitro, ovaries were collected from dairy cows on day 6.1 +/- 0.2 or day 14.8 +/- 0.2 of the oestrous cycle to obtain steroidogenically active DF1 (n = 8) and DF2 (n = 7). Granulosa and thecal cells were isolated, dispersed and incubated for 16 h with testosterone (granulosa cells) or forskolin or bLH (thecal cells). Both types of cell were subsequently cultured for 9 days with forskolin and insulin. The viability of the granulosa cells was similar in DF1 and DF2, but the concentration of oestradiol in the follicular fluid was higher in DF1 than in DF2. Production of oestradiol and progesterone by granulosa cells was similar in DF1 and DF2, but androstenedione and progesterone production by thecal cells were 3.5-6.5-fold higher in DF1 than in DF2. During the 9 days of luteinization, progesterone production was similar in DF1- and DF2-derived granulosa cells, but was two- to three-fold higher in DF1- than in DF2-derived thecal cells. Experiments were also conducted in vivo. In Expt 1 in vivo, lactating cows that were assigned to ovulate DF1 or DF2 (n = 9 and 13 in replicate 1 and 2, respectively) were injected with PGF2 alpha on days 6 and 7 or on days 14 and 15 of the oestrous cycle, respectively. A wave by replicate interaction was detected for plasma progesterone concentration in the subsequent cycle: in the first replicate, progesterone production was approximately 40% higher in cows that ovulated DF1; in the second replicate, progesterone production was similar in cows that ovulated DF1 or DF2. In Expt 2, pooled plasma progesterone in the mid-luteal phase (days 12-15) after insemination of pregnant and non-pregnant cows was approximately 30% higher in cows that had ovulated DF1 (n = 32) than in cows that had ovulated DF2 (n = 22). This study showed DF1 had a higher steroidogenic capacity compared with DF2, which may be related to the hormonal environment in which the follicles developed.     

Non-invasive assessment of the reproductive cycle in free-ranging female African elephants (Loxodonta africana) treated with a gonadotropin-releasing hormone (GnRH) vaccine for inducing anoestrus

ABSTRACT: BACKGROUND: In southern Africa, various options to manage elephant populations are being considered. Immunocontraception is considered to be the most ethically acceptable and logistically feasible method for control of smaller and confined populations. In this regard, the use of gonadotropin-releasing hormone (GnRH) vaccine has not been investigated in female elephants, although it has been reported to be safe and effective in several domestic and wildlife species. The aims of this study were to monitor the oestrous cycles of free-ranging African elephant cows using faecal progestagen metabolites and to evaluate the efficacy of a GnRH vaccine to induce anoestrus in treated cows. METHODS: Between May 2009 - June 2010, luteal activity of 12 elephant cows was monitored non-invasively using an enzyme immunoassay detecting faecal 5alpha-reduced pregnanes (faecal progestagen metabolites, FPM) on a private game reserve in South Africa. No bulls of breeding age were present on the reserve prior to and for the duration of the study. After a 3-month control period, 8 randomly-selected females were treated twice with 600 micrograms of GnRH vaccine (Improvac[REGISTERED SIGN], Pfizer Animal Health, Sandton, South Africa) 5-7 weeks apart. Four of these females had been treated previously with the porcine zona pellucida (pZP) vaccine for four years (2004-2007). RESULTS: All 12 monitored females (8 treated and 4 controls) showed signs of luteal activity as evidenced by FPM concentrations exceeding individual baseline values more than once. A total of 16 oestrous cycles could be identified in 8 cows with four of these within the 13 to 17 weeks range previously reported for captive African elephants. According to the FPM concentrations the GnRH vaccine was unable to induce anoestrus in the treated cows. Overall FPM levels in samples collected during the wet season (mean 4.03 micrograms/gram dry faeces) were significantly higher (P<0.002) than the dry season (mean 2.59 micrograms/gram dry faeces). CONCLUSIONS: The GnRH vaccination protocol failed to induce anoestrus in the treated female elephants. These results indicate that irregular oestrous cycles occur amongst free-ranging elephants and are not restricted to elephants in captivity. The relationship between ecological conditions and endocrine activity were confirmed. Free-ranging female elephants were observed to not cycle continuously throughout the year in the absence of adult bulls.