Feeding ergot to pregnant ewes

Ergot found on barley and varieties of grains and grasses has been a problem to human and animal health for centuries and has been implicated in causing decreased reproductive performance. This study was initiated to investigate the effects of feeding ergot to ewes during gestation. It was observed that supplementing ewes with a ration that contained 0.1, 0.5 or 0.7% ergot decreased the percent ewes lambing by approximately 20% but had no effect on the number of lambs born per ewe lambing. It was concluded that ergoty grains should not be fed to breeding or pregnant ewes.     

Prolactin response to synthetic TRF in pregnant ewes.

The prolactin secretion response to TRF was similar at all stages of pregnancy (Days 40, 66, 102 and term).     

Ovarian and uterine prostaglandin E2-9-ketoreductase activity in cyclic and pregnant ewes.

The regulation of luteal function in sheep appears to be dependent in part upon relative utero-ovarian concentrations of PGE2 and PGF2 alpha. Prostaglandin E2-9-ketoreductase converts PGE2 (a putative antiluteolysin) to PGF2 alpha. Enzymatic activity was measured in a cytosolic subcellular fraction of luteal and endometrial tissues collected on days 10, 13 and 16 of the estrous cycle or pregnancy. Respective days represented times before, during, and after the critical period for maternal recognition of pregnancy. Preparations of enzyme were incubated in the presence of tritiated PGE2. Radiolabeled PGF2 alpha (ie., product) was separated from PGE2 by gel filtration chromatography and quantified by liquid scintillation spectrometry. There were no significant differences due to time of tissue collection or pregnancy status in enzymatic activity of luteal tissues. Prostaglandin E2-9-ketoreductase activity isolated from endometria of open ewes was greater than their pregnant counterparts on days 13 and 16. Thus, the potential capacity of the ovine uterus to generate luteolytic PGF2 alpha from PGE2 substrate is elevated during an infertile estrous cycle.     

Ovarian function in ewes during the transition from breeding season to anoestrus

Transrectal ovarian ultrasonography was conducted in six Western white-faced ewes for 35 days from the last oestrus of the breeding season, to record the number and size of all ovarian follicles > or = 3 mm in diameter and luteal structures. Blood samples were collected once a day for estimation of serum concentrations of follicle-stimulating hormone (FSH), oestradiol and progesterone. Each ewe had five follicular waves (follicles growing from 3 to > or = 5 mm in diameter) over the scanning period. The duration of the growth phase of the largest ovarian follicles did not differ (P > 0.05) between waves, but follicular static and regressing phases decreased significantly (P < 0.05) after the decline in serum progesterone concentrations at the end of the last luteal phase of the breeding season. The intervals between the five follicular waves were: 9.2+/-0.4, 5.2+/-0.7, 8.3+/-0.8 and 5.8+/-0.7 days; the two shorter intervals differed (P < 0.05) from the two longer intervals. Using the cycle-detection program, rhythmic increases in serum FSH concentrations were detected in all ewes; the amplitude, duration and periodicity of FSH fluctuations did not vary (P > 0.05) throughout the period of study. The number of identified FSH peaks (7.8+/-0.5 peaks per ewe, per scanning period) was greater (P < 0.05) than the number of emerging follicular waves. Serum concentrations of oestradiol remained low (< or = 1 pg/ml) on most days, in five out of the six ewes studied, and sporadic elevations in oestradiol secretion above the non-detectable level were not associated with the emergence of follicular waves. The ovulation rate was lower than that seen during the middle portion of the breeding season (November-December) in white-faced ewes but the transitional ewes had larger corpora lutea (CL). Maximal serum concentrations of progesterone appeared to be lower and the plateau phase of progesterone secretion appeared to be shorter during the last luteal phase of the ovulatory season in comparison to the mid-breeding season of Western white-faced ewes. During the transition into anoestrus in ewes, the endogenous rhythm of FSH release is remarkably robust but the pattern of emergence of sequential follicular waves is dissociated from FSH and oestradiol secretion. Luteal progesterone secretion is suppressed because of fewer ovulations and diminished total luteal volume, but it may also result from diminished gonadotropic support. These season-related alterations in the normal pattern of ovine ovarian cycles appear to be due to reduction in ovarian responsiveness to gonadotropins and/or attenuation in secretion of luteinizing hormone (LH) occurring at the onset of the anovulatory season in ewes.     

Ovarian response to PMSG treatment in ewes immunized against oestradiol-17 beta

The effects of active immunization against oestradiol-17 beta on the ovarian response to pregnant mare serum gonadotrophin (PMSG) was investigated in Merino ewes. Immunized (79) and control (41) ewes were synchronized with intravaginal sponges, given either 750 or 1500 i.u. PMSG and then mated to rams or inseminated laparoscopically with fresh diluted semen. All control ewes mated naturally exhibited oestrus and 40 out of 41 control ewes ovulated. The ovulation rate was higher in the controls receiving 1500 i.u. PMSG than in those ewes which received 750 i.u. PMSG (10.2 v. 3.3). Immunization against oestradiol-17 beta resulted in antibody titres varying from 100 to more than 100 000 in plasma taken 1-4 days after mating. The ovarian response increased significantly in the lowest titre group (100-1000) in conjunction with stimulation with 1500 i.u. PMSG. In these ewes the ovulation rate increased over controls (16.7 v. 10.2) as did the total ovarian response, which includes follicles greater than 10 mm diameter (22.3 v. 11.1). The total ovarian response was also increased in those ewes given 750 i.u. PMSG which had titres in the 1000-10 000 and 10 000-100 000 range, but this was not accompanied by significant increases in the ovulation rate. In general, the higher titre levels (greater than 1000) were correlated with decreases in the proportion of ewes showing oestrus and ovulating and in the embryo recovery rate. The 1500 i.u. PMSG treatment group with the highest titres (greater than 10 000) also showed a significant drop in the ovulation rate as compared to the 1500 i.u. PMSG controls.     

Effect of undernutrition in foetal life on energy expenditure during gestation in ewes

The long-term effect of early life undernutrition on late gestation energy expenditure (EEgest) was investigated in sheep. Ewes were fed either adequate (100%) or restricted (60%) energy and protein during late foetal life as well as during last trimester of gestation later in life, resulting in three groups: Adequate-Adequate (AA, n = 5), Adequate-Restricted (AR, n = 5) and Restricted-Restricted (RR, n = 5). At two weeks pre-partum, EEgest were calculated from respiratory gaseous exchange and nitrogen excreted in urine and further it was partitioned to energy expenditure for conceptus development (EEconceptus) and homeorhetic adaptations in maternal metabolism (EEhomeorhetic). Late gestational energy and protein restriction reduced the EEgest in the AR ewes (4.1 MJ x d(-1)) but not in the RR ewes (5.2 MJ x d(-1)) compared with the AA ewes (6.8 MJ x d(-1)). Based on conceptus-weight, no significant difference was found in EEhomeorhetic among the groups; 172, 175 and 169 kJ/kg x d(-1) in AA, AR and RR ewes, respectively. However, EEconceptus was significantly lower in AR (135 kJ/kg x d(-1)) in comparison with AA (298 kJ/kg x d(-1)) and RR (252 kJ/kg x d(-1)) ewes. In conclusion, exposure nutrient restriction in early life impairs the ability of ewes to respond to nutritional restriction in terms of energy expenditure of gestation.     

Ovarian response to gonadotropin treatment initiated relative to wave emergence in ultrasonographically monitored ewes

Follicular recruitment and luteal response to superovulatory treatment initiated relative to the status of the first wave of the ovine estrous cycle (Wave 1) were studied. All ewes (n = 25) received an intravaginal progestagen sponge to synchronize estrous cycles, and ewes were monitored daily by transrectal ultrasonography. Multiple-dose FSH treatment (total dose = 100 mg NIH-FSH-P1) was initiated on the day of ovulation (Day 0 group) in 16 ewes. In the remaining 9 ewes, FSH treatment was started 3 d after emergence of the largest follicle of Wave 1 (Day 3 group). Ewes received PGF(2alpha) with the last 2 FSH treatments to induce luteolysis. Daily blood samples were taken to determine progesterone profiles and to evaluate the luteal response subsequent to superovulation. The ovulation rate was determined by ultrasonography and correlated with direct observation of the ovaries during laparotomy 5 to 6 d after superovulatory estrus when the uterus was flushed to collect embryos. Results confirmed that follicular recruitment was suppressed by the presence of a large, growing follicle. In the Day 0 and Day 3 groups, respectively, mean numbers (+/- SEM) of large follicles (>/= 4 mm) recruited were 6.4 +/- 0.6 and 2.7 +/- 0.7 (P < 0.01) at 48 h after the onset of treatment, and 6.7 +/- 0.5 and 5.1 +/- 0.6 (P = 0.08) at 72 h after the onset of treatment. Ovulation rates were 5.6 +/- 0.8 and 3.3 +/- 0.8 in the respective groups (P < 0.05). The number of transferable embryos was 1.8 +/- 0.5 and 0.3 +/- 0.2 in the respective groups (P < 0.05). Short luteal phases (相似文献   

Transplacental transfer of medetomidine and ketamine in pregnant ewes

The extent of placental transfer of medetomidine and ketamine is unknown in pregnant ewes. Date-mated singleton (n = 8) and twin (n = 8) pregnant merino cross ewes were anaesthetized for Caesarean delivery of preterm lamb fetuses. A combination of medetomidine (20 μg/kg) and ketamine (10 mg/kg) was administered by intravenous injection and surgery performed immediately thereafter. Blood samples were collected from the ewe at one, five and 10 min after intravenous injection and from the umbilical vein of the fetus at delivery. Non-pregnant ewes were also anaesthetized (n = 8). There was no difference in the plasma concentration of medetomidine or ketamine when comparing singleton and twin ewes or pregnant and non-pregnant ewes for the short duration of the study. Fetal plasma concentrations of each drug were comparable to the maternal concentrations at the same time. We conclude that both drugs cross the placenta readily and provide anaesthesia and analgesia for the fetus when it is delivered.     

Plasma vitamin D metabolite levels in pregnant and nonpregnant ewes

1. Maternal calcium homeostasis during pregnancy is strained due to fetal mineral requirements for bone formation. 2. In most species, the mother adjusts to the mineral requirements of the fetus with alterations in her metabolism of vitamin D that include a decrease in plasma 25-(OH)D levels and an increase in circulating levels of the hormone, 1,25-(OH)2D. 3. Plasma 25-(OH)D and 1,25-(OH)2D levels in adult male, adult female and pregnant sheep were measured by specific radioreceptor binding assays. 4. Pregnancy did not alter circulating levels of 25-(OH)D or 1,25-(OH)2D in the sheep. 5. The pregnant ewe differs from all species studied to date in that maternal plasma 1,25-(OH)2D levels do not rise as a result of pregnancy.     

Ovarian function in ewes at the onset of the breeding season

Transrectal ultrasonography of ovaries was performed each day, during the expected transition from anoestrus to the breeding season (mid-August to early October), in six Western white-faced cross-bred ewes, to record ovarian antral follicles > or = 3 mm in size and luteal structures. Jugular blood samples were collected daily for radioimmunoassay (RIA) of follicle-stimulating hormone (FSH), oestradiol and progesterone. The first ovulation of the breeding season was followed by the full-length oestrous cycle in all ewes studied. Prior to the ovulation, all ewes exhibited a distinct increase in circulating concentrations of progesterone, yet no corpora lutea (CL) were detected and luteinized unovulated follicles were detected in only three ewes. Secretion of FSH was not affected by the cessation of anoestrus and peaks of episodic FSH fluctuations were associated with the emergence of ovarian follicular waves (follicles growing from 3 to > or = 5 mm). During the 17 days prior to the first ovulation of the breeding season, there were no apparent changes in the pattern of emergence of follicular waves. Mean daily numbers of small antral follicles (not growing beyond 3 mm in diameter) declined (P < 0.05) after the first ovulation. The ovulation rate, maximal total and mean luteal volumes and maximal serum progesterone concentrations, but not mean diameters of ovulatory follicles, were ostensibly lower during the first oestrous cycle of the breeding season compared with the mid-breeding season of Western white-faced ewes. Oestradiol secretion by ovarian follicles appeared to be fully restored, compared with anoestrous ewes, but it was not synchronized with the growth of the largest antral follicles of waves until after the beginning of the first oestrous cycle. An increase in progesterone secretion preceding the first ovulation of the breeding season does not result, as previously suggested, from the ovulation of immature ovarian follicles and short-lived CL, but progesterone may be produced by luteinized unovulated follicles and/or interstitial tissue of unknown origin. This increase in serum concentrations of progesterone does not alter the pattern of follicular wave development, hence it seems to be important mainly for inducing oestrous behaviour, synchronizing it with the preovulatory surge of luteinizing hormone (LH), and preventing premature luteolysis during the ensuing luteal phase. Progesterone may also enhance ovarian follicular responsiveness to circulating gonadotropins through a local mechanism.     

Ovarian capillary blood flow in seasonally anoestrous ewes induced to ovulate by treatment with GnRH

The microsphere technique was used to obtain estimates of ovarian capillary blood flow near ovulation, in 8 seasonally anoestrous ewes, which were induced to ovulate by GnRH therapy. Plasma progesterone concentrations were monitored in jugular blood sampled between Days 4 and 7 after the onset of the preovulatory LH surge. The ewes were then slaughtered. Three of the ewes were treated with a single injection of 20 mg progesterone before GnRH therapy. In these ewes and 1 other, plasma progesterone values increased after ovulation and reached 1.0 ng/ml on Day 7 following the preovulatory LH surge (normal, functional CL), whilst in the other 4 ewes progesterone concentrations increased initially then declined to 0.5 ng/ml by Day 7 (abnormal CL). In the ewes exhibiting normal luteal function, the mean ovarian capillary blood flow was significantly greater (P less than 0.01) than that for ewes having abnormal luteal function. Irrespective of the type of CL produced, capillary blood flow was significantly greater (P less than 0.05) in ovulatory ovaries than in non-ovulatory ovaries. These findings indicate that the rate of capillary blood flow in ovaries near ovulation may be a critical factor in normal development and maturation of preovulatory follicles and function of subsequently formed CL.     

Short-term responses of decomposers to flow restoration in Fossil Creek,Arizona, USA

Dam decommissioning projects, although numerous, rarely include complete sets of data before and after restoration for evaluating the ecological consequences of such projects. In this study, we used a before-after control-impact (BACI) design to assess changes in leaf litter decomposition and associated macroinvertebrate and fungal decomposers following dam decommissioning in Fossil Creek, Arizona, USA. Leaf litterbags were deployed in a relatively pristine site above the dam and a highly disturbed site below the dam where over 95% of the flow was previously diverted for hydropower generation. Leaf litter decomposition was significantly slower below the dam both measurement years (pre- and post-restoration) with no site-year interaction, indicating that decomposition in this stream section was not affected by increased flow. In contrast, both macroinvertebrates and fungi differed significantly above and below the dam prior to restoration but were similar post-restoration, supporting the concept that decomposer communities can quickly rebound following reintroduction of full flow. Our results indicate that some aquatic ecosystem variables can return to a more natural state following ecological restoration activities such as water flow restoration. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: S. Stendera     

Tocopherol induced angiogenesis in placental vascular network in late pregnant ewes

Background  

Tocopherols have biphasic, proangiogenic and antiangiogenic therapeutic effects. The objective of this clinical trial was to clarify tocopherol's placental angiogenic potential in late pregnant ewes following oral supplementation.     

Ovarian follicular dynamics after cauterization of the dominant follicle in anestrous ewes

An experiment was conducted to ascertain if follicles could reach ovulatory size after the largest follicle (dominant) has been removed at different times during a progestin treatment in anestrous ewes, and secondly to determine if these new follicles could respond to an hCG-induced ovulation and have similar function as corpora lutea. Mature crossbred sheep (n=44) in anestrous were treated with an intravaginal sponge containing 40 mg of FGA (day 0=sponge insertion) for 9 days. Treatments consisted of cauterization of the largest follicle on the experimental day 3 (T1), day 6 (T2) and day 9 (T3); day 12 to ascertain the size of the largest follicle in control ewes. During laparotomies, the diameters of the largest follicle (DF), and those of the second and third largest follicles (SF1 and SF2, respectively) were determined. On day 12, a second laparotomy was performed for those ewes which had their DF cauterized on days 3, 6 and 9, a fourth group was left intact and only laparotomized on day 12. At this time, the size of the new DF, SF1 and SF2 were determined. Immediately after the laparotomy on day 12, all the ewes were treated with 1000 i.u. of hCG to induce ovulation. Blood samples were collected daily from day 0 to 50 and samples were analyzed for progesterone concentrations. The size of the DF at the time of sponge removal was smaller that those observed on day 3 or 6 of sponge suggesting that follicles in ewes treated with this progestin regress and a new wave of follicular development ensues between day 6 and the time of sponge removal. The size of the DF on day 12 was also smaller in ewes that have the largest follicle removed at the time of sponge removal reflecting that these follicles had a shorter period of growth; however, the rate of growth was greater for these follicles than for follicles arising after cauterization on day 3 or 6 after sponge insertion. There were no differences among treatments, in the number of ewes that formed a corpus luteum (CL) in response to hCG. Life span of the corpora lutea did not differ among ewes having their DF removed on day 6 or 9 or those that served as controls, however, ewes that had their DF removed on day 3 developed longer lived CL in a larger proportion of animals. Average progesterone concentration during the life span of the induced corpora lutea was greater in control ewes than in any other experimental group. These observations allow us to conclude that, (a) the follicular dynamics observed in anestrous ewes treated with a progestin intravaginal sponge resembles that observed during the normal estrous cycle in the ewe; (b) the effects of progesterone on life span of the corpus luteum could not be only related to direct effects at the follicle but also involve changes in other components of the uterine-ovarian-hypothalamic axis; (c) the mechanisms controlling luteal life span seem to be different to those mechanisms controlling the function of the induced corpus luteum.     

Ovarian follicular populations and preovulatory enlargement in Booroola and control Merino ewes

To investigate the factors contributing to the different ovulation rates observed in two strains of sheep (Booroola 5.2, Merino 1.2), in-vivo monitoring of follicular kinetics followed by histological examination of both ovaries was performed during the late luteal and follicular phases. Ewes of both strains were either ovariectomized at Day 13, or had the 3 largest follicles of each ovary ink-labelled at Day 13 and were ovariectomized at Day 15, or had the 3 largest follicles of each ovary ink-labelled at Days 13 and 15 and were ovariectomized 16 h after the beginning of oestrus (N = 6 per time per strain). In another experiment, the age effects on the follicular populations of these two strains were also studied. There were 2-4 times more primordial follicles and 1.5-2 times more preantral follicles in the ovaries of Booroola than in control Merino ewes, although the number of antral follicles was the same. The percentage of normal follicles in this population was higher in Merino than Booroola ovaries. In Booroola ewes, there was no correlation between the number of antral follicles per ovary and the ovulation rate at the previous cycle (r = 0.22). This suggests that follicle numbers do not play a key role in the high ovulation rate of the Booroola strain. The number of follicles initiating growth from the primordial pool, the number of growing follicles disappearing at the preantral stage, the pattern of antrum development, granulosa cell multiplication and appearance of atresia differed between strains. The reasons for the high ovulation rate of the Booroola strain became clear when preovulatory enlargement was followed by ink labelling. An extended period of time during which recruitment of ovulatory follicles takes place, together with a low incidence of selection and the ability of the follicles to wait for ovulation are the features involved in this high ovulation rate.     

Prevention of suckling improves postpartum reproductive responses to hormone treatments in Pelibuey ewes

To determine the effects of suckling on postpartum (pp) reproductive efficiency in Pelibuey ewes, two experiments were performed. In Experiment 1, 112 ewes were randomly assigned to one of two groups at parturition: Without restriction of suckling (WRS) 24 h day(-1) for 60 days (n=56), and Weaned Ewes (WE), weaned at 40 days pp (n=56). On Day 30 pp, all ewes were given Prostaglandin (PGF2alpha) and one of four treatments (n=14): T1, intravaginal progestagen (FGA; 40 mg) for 12 days from day 30 pp+equine chorionic gonadotropin (eCG; 300 UI) until 2 days before removing FGA; T2, FGA was applied for 12 days; T3, a second application of PGF2alpha was given on day 40 pp+eCG on the same day; T4, a second injection of PGF2alpha was applied on day 40 pp only. In all the analyzed characteristics, the best results were obtained in WE. Within the WE group, the best treatment (P<0.05) was T1 with 85.7% of the ewes in oestrus, 71.4% pregnant and a prolificacy of 1.9. Within the WRS group the best results were observed in T1. In both groups, the lowest results (P<0.05) were obtained in T4. In Experiment 2, 75 ewes were randomly assigned to one of three groups (n=25) immediately after parturition: Group 1, Without restriction of suckling (WRS, as in Experiment 1); Group 2, with restriction of suckling (RS; suckling for 30 min day(-1)); Group 3, Early Weaning (EW: at 7 days pp). All ewes were given PGF2alpha at 30 days pp and the same hormonal treatment, FGA for 12 days+PGF2alpha and eCG 2 days before removing FGA. No differences were observed (P>0.05) between RS and EW for the presentation of oestrus (96% vs. 92%), pregnancy (72% vs. 76%) or prolificacy (1.9 vs. 1.9), although group WRS did not perform (P<0.05) as well as groups RS and EW for any measure of performance. In conclusion, the combination of hormonal treatment (FGA plus eCG) with weaning at 7 or 40 days pp, or restricted suckling, improves postpartum reproductive efficiency in Pelibuey ewes, demonstrating the inhibitory role of suckling on postpartum reproduction in this breed.