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Results 451 - 500 of 872
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Zarazaga L A - - 1997
An experiment was designed to study if, in the same animals, characteristics of the plasma melatonin rhythm vary during pregnancy in ewes. Thirteen Ile-de-France ewes were maintained in natural photoperiod and measurements of the characteristics of the rhythm of melatonin secretion were determined during one estrous cycle and then during ...
Clarke L - - 1997
Although body condition score was not significantly different between light (<55 kg, n = 6) and heavy (> or =60 kg, n = 7) ewes at mating, it declined between Day 30 and Day 90 of gestation in light but not heavy ewes, and remained lower up to term. All ...
Bird I M - - 1997
During pregnancy, the uterine artery demonstrates refractoriness to vasoconstriction by infused angiotensin II (AII). AII increases prostacyclin (PGI2) production by uterine artery endothelium from pregnant ewes, and this response is mediated via the AT1 receptor (AT1-R). This response is also unique to pregnancy because AII does not stimulate PGI2 production ...
I'anson H - - 1997
Growth retardation induced by dietary restriction in the lamb results in a low GnRH pulse frequency, and thus, puberty is delayed. In our experimental model, in which ovariectomized lambs are maintained at weaning weight (approximately 20 kg BW), hypothalamic GnRH is present and releasable, suggesting that central mechanisms limit the ...
McAllister M M - - 1996
Six groups of six pregnant ewes each were inoculated with 170,000 or 1,700,000 tachyzoites of Neospora caninum on gestation day 65, 90, or 120. All ewes seroconverted, and none showed signs of illness other than abortion. Regardless of the inoculum dose, all ewes inoculated on gestation day 65 aborted; ewes ...
Gerhardt K J - - 1996
PURPOSE: Although the air-conduction pathway is the principal mode of sound transmission to the inner ear, this may not be true for the fetus in utero. The fetus detects and responds to sounds in the maternal environment. Exogenous sounds can reach the fetal inner ear through the ear canal and ...
Powell M R - - 1996
Ten experiments utilizing 1,659 ewes were conducted to determine the potential of melengestrol acetate (MGA)-based treatments in inducing and synchronizing estrous activity in ewes during the nonbreeding season. In May or June, ewes were given .25 mg of MGA.ewe-1.d-1 or control diet and(or) a subsequent i.m. injection of zeranol, estradiol-17 ...
Shulkes A - - 1996
1. Plasma gastrin releasing peptide (GRP) is elevated in the foetal and maternal circulations of pregnant sheep. To determine the mechanisms for this increase the synthesis, secretion rate, metabolism and placental transfer of GRP were measured. 2. Foetal metabolic clearance rate of GRP was significantly increased (P < 0.05) compared ...
Lumbers E R - - 1996
To find out which of the effects of angiotensin converting enzyme (ACE) inhibitors on the fetus are due to their actions in the mother and which are direct effects due to blockade of the fetal renin-angiotensin system, enalapril (150 mg twice daily i.v.), which does not readily cross the sheep ...
Ipson M A - - 1996
Substantial alterations occur in female reproductive tissues to ensure the successful outcome of and recovery from pregnancy. Although sheep have been widely used to study several aspects of pregnancy, little information is available regarding alterations in myometrial function. We therefore characterized the alterations that occur in ovine myometrial stress-generating capacity ...
Cantero A - - 1996
The effects of prolonged exposure to phyto-oestrogens (coumestrol) on the morphology of the reproductive organs of ewes were studied in 28 lucerne-grazing animals, and compared with 28 control ewes given a standard coumestrol-free diet. The anatomical studies showed that 43% of the ewes fed lucerne displayed macroscopic changes within the ...
Iman N Y - - 1996
Lifetime (5 yr) lamb production and wool production from 207 straightbred Targhee (T) and 474 1/4 Finn-1/4 Dorset-1/2 Targhee (FDT) crossbred ewes managed in a range or farm flock system were evaluated for ewe fertility, prolificacy, ewe fleece weight, and total lamb weight weaned per ewe exposed. Data included 2,620 ...
Perkins N R - - 1996
Synchronized ewes (n = 217) were bred by laparoscopic insemination of frozen-thawed semen from 1 of 3 rams. The ewes were bred by either a double (110 ewes) or single horn (107 ewes) technique without regard to the site of ovulation. There was no difference in the percentage of ewes ...
Davey M G - - 1996
We have determined the effects of preterm birth on the postnatal development of ventilatory responses to progressive hypoxia and hypercapnia in awake lambs. Hypoxic and hypercapnic rebreathing tests were performed at weekly intervals in 5 preterm (born at 135 +/- 0.5 d) and 5 term (born at 146 +/- 0.2 ...
Vos E A - - 1996
Both free and conjugated fecal estrogens were surveyed in sows by means of RIA's after extraction and column chromatography. Six different RIA's were performed using the same fecal suspension. Based on differences in concentration in feces from 6 pregnant and 4 nonpregnant sows, estrone (E1) was selected for the development ...
O' Doherty J V - - 1996
In the ewe, high level feeding is associated with low levels of circulating progesterone and that progesterone withdrawal is a prerequisite for lactogenesis and the onset of copious milk secretion. A total of 108 ewes was allocated to a 3 x 2 factorial experiment to determine the effect of diet ...
Lewis R M - - 1996
Effects of environmental factors such as ewe age, season of exposure, and time from lambing to exposure on fertility were evaluated using records on 1,084 Dorset ewes in the STAR accelerated lambing system. The STAR program consisted of five 30-d concurrent breeding and lambing periods per year beginning on January ...
Wallace J M - - 1996
A highly controlled model to investigate nutrient partitioning and the control of fetal growth in the rapidly growing adolescent sheep is described. Embryos recovered from superovulated adult ewes inseminated by a single sire were transferred in singleton to the uterus of prepubertal adolescent recipients induced to ovulate at 21 weeks ...
Parraguez V H - - 1996
A 24-h rhythm of plasma PRL is present in fetal sheep. This rhythm is synchronized to an environmental clue (zeitgeber). We determined whether the light-dark cycle (L:D) is a zeitgeber for the fetal PRL rhythm and, if so, whether the mother might convey this zeitgeber to the fetus. We kept ...
Akinbami M A - - 1996
Experiments were conducted to determine 1) if pregnancy initiated on Day 32 post partum would be maintained until lambing, 2) if there is a difference in the ability of the previously gravid or nongravid uterine horn to maintain pregnancy, and 3) if season has an effect on embryo loss. Estrus ...
Papp J R - - 1996
Enzootic abortion in sheep, caused by Chlamydia psittaci, has been associated with pregnancy failure in most sheep-producing countries. Late-term abortions or the birth of weak low-birth-weight lambs occurred following primary C. psittaci infection in pregnant ewes. However, the mode by which C. psittaci can be transmitted among sheep has not ...
West H J - - 1996
There is a paucity of information on the metabolic effects of undernutrition of the ewe carrying multiple fetuses in late pregnancy. In the present study the effects of induction of ketosis from 132 d gestation in ewes carrying twin fetuses were compared with a control group. The ewes were well ...
Pfister J A - - 1996
Locoweeds (Oxytropis and Astragalus spp.) are toxic plants found on many rangelands. Preferences for locoweed are learned; livestock often initially reject the plant, but learn to eat locoweed after continued exposure. Maternal influences are important in shaping diet selection in young animals. We studied the influence of ewe consumption of ...
Borjesson D L - - 1996
We developed and validated an enzyme immunoassay for immunoreactive pregnanediol-3-glucuronide (iPdG) in feces to monitor reproductive status in desert and Rocky Mountain bighorn sheep (Ovis canadensis). Fecal iPdG concentrations were strongly correlated (r = 0.71) with serum progesterone concentrations in paired fecal and blood samples collected from 34 free-ranging desert ...
Schermer S J - - 1996
The effect of fetal thyroidectomy on thermoregulation in newborn lambs was investigated. Seven of 14 lambs born normally at term were thyroidectomized at Day 127 of gestation. Colonic temperature and oxygen consumption were measured during non-rapid eye movement sleep 6-45 h after birth. All lambs were then killed and perirenal ...
Dwyer C M - - 1996
To distinguish between ewe and lamb breed effects on prenatal growth, ease of parturition and early lamb behaviour, an embryo-transfer study was carried out using a hill breed (Scottish Blackface; liveweight: 54.25 +/- 1.03 kg, mean +/- s.e.m.) and a lowland breed (Suffolk; 80.33 +/- 1.52 kg) to obtain the ...
Lakritz J - - 1995
The purpose of this study is to describe a developmental defect of the caudal cervical and cranial thoracic vertebrae in 11 purebred Colombia lambs. The lambs were either affected at birth, or developed the condition within the first 18 days of age. Cervicothoracic kyphosis, with a compensatory cervical lordosis and ...
Ueda T - - 1995
Effects of prenatal corticosteroid on the properties of surfactant have not previously been evaluated. A single ultrasound-guided fetal injection with 0.5 mg/kg betamethasone 48 h before delivery of preterm lambs at 134- to 135-days gestation improved oxygenation, lowered the ventilatory pressures required to maintain arterial PCO2 between 30 and 40 ...
Bunge R - - 1995
Two- and three-year-old F1 crossbred ewes produced from Suffolk and Targhee dams and sires of the prolific wool breeds of Finnsheep, Combo-6, and Booroola Merino and the hair breeds of St. Croix and Barbados were pasture-mated to Dorset rams over a 4-yr period at the Dixon Springs Agricultural Center in ...
Deprest J A - - 1995
OBJECTIVE: Our purpose was to evaluate the feasibility of intrauterine endoscopic fetal surgery in a fetal lamb model by creating a urinary tract obstruction. STUDY DESIGN: Lower urinary tract obstruction was created by ligation of the urethra and urachus in 21 fetal lambs, eight at 95 to 105 days' gestation ...
Windsor D P - - 1995
The experiments described examined the effects of a number of factors on the level of uterine insemination achieved in Merino ewes by a transcervical insemination technique (Guelph system for transcervical artificial insemination; GST-AI). Cervical penetration rate is an important limitation to the use of such methods in Merinos. Simulated insemination ...
Broad K D - - 1995
In the multiparous ewe, intracerebroventricular (i.c.v.) infusions of corticotrophin releasing factor (CRF) act centrally to facilitate the induction of maternal behaviour if administered with vaginocervical stimulation. Changes in CRF mRNA expression in the brains of multiparous ewes were therefore examined as a function of late pregnancy, parturition and lactation using ...
Willard J M - - 1995
Ovine pregnancy-specific protein B (oPSPB) was isolated from sheep placentas. Antiserum to oPSPB was developed in rabbits. A quantitative RIA was developed and used to assay the serum concentrations of oPSPB during and after pregnancy in ewes bearing single or twin fetuses. Suffolk and Panama ewes, kept with rams equipped ...
Sargison N D - - 1995
A naturally occurring outbreak of sheep scab in a flock of 202 ewes during mid-pregnancy resulted in exudation from the scab lesions and hypoalbuminaemia lasting for two to 10 weeks in the severely affected ewes. The serum albumin concentration at the time of diagnosis and two weeks after treatment with ...
Boulton M I - - 1995
The aim of this study was to investigate the role of FSH in the control of ovulation rate by the Booroola gene. Three Booroola genotypes (FecBFecB, FecBFec+ and Fec+Fec+) of the F2 population, from a cross between Booroola Merino and Scottish Blackface, and two Booroola genotypes (FecBFec+ and Fec+Fec+; 25% ...
Wallace J M - - 1995
We examined the key events underlying maternal recognition of pregnancy and the prevention of luteolysis in early postpartum ewes by synchronously transferring single expanded blastocysts recovered from control ewes on day 11 of pregnancy into the uterus of either postpartum recipients that had been induced to ovulate 28 days after ...
Bauer M K - - 1995
Nutrition is a major determinant of the somatotropic axis during postnatal life. However, little is known about the response of the fetal somatotropic axis to nutritional limitation. From day 100 of gestation (term = 147 days), singleton-bearing ewes were fed either ad libitum (control; n = 6) or 25% of ...
Hunter J G - - 1995
The objective of this study was to evaluate the physiologic consequences of a pneumoperitoneum (pneumo) to the midterm fetus in a pregnant sheep model. The performance of laparoscopic cholecystectomy (LC) during pregnancy is controversial. The primary concern regarding the safety of LC during pregnancy is the physiologic consequences of the ...
Santos A C - - 1995
BACKGROUND: Ropivacaine is a new amide local anesthetic, having therapeutic properties similar to those of bupivacaine but with a wider margin of safety. Bupivacaine is probably the most commonly used drug in obstetric epidural analgesia, even though laboratory studies have suggested that pregnancy increases the cardiotoxicity of bupivacaine but not ...
Bassett J M - - 1995
The mean (+/- sd) packed cell volume (PCV) of the lambs in a flock mated by 'out-of-season' breeding methods and housed throughout the last six weeks of pregnancy and the whole of the suckling period declined to 23.3 +/- 3.34 per cent when the lambs were a month old, but ...
Panter K E - - 1995
Selenium fed to open cycling ewes in the form of sodium selenate or Astragalus bisulcatus (a selenium accumulator plant) at 24 or 29 ppm selenium, respectively, in alfalfa hay pellets did not alter the estrous cycle length, estrus behavior, progesterone or estrogen profiles, pregnancy rate or outcome of parturition (P ...
Desta B - - 1995
Experiments were designed to investigate the mechanism underlying the endothelium-dependent relaxation to trandolaprilat, a converting enzyme inhibitor, in canine coronary arteries previously exposed to bradykinin. Rings suspended in organ chambers were exposed to bradykinin for 3 min and washed repeatedly for 150 min. Trandolaprilat caused relaxations [IC50(-log M)8.59] in rings ...
Sterning M - - 1995
The pregnancy rate and the subsequent litter size were studied in 332 Swedish Yorkshire primiparous sows, fed according to a commercial Swedish feeding regime during lactation. The sows were weighed and backfat depth was recorded at the first farrowing, at weaning, and at mating. Oestrous detection was performed once daily ...
McMillen I C - - 1995
We have investigated whether the maternal melatonin rhythm provides the fetus with either a circadian or seasonal 'signal' during development. Our findings provide evidence that melatonin can generate and entrain the early evening peak in the daily rhythm of fetal breathing movements. In contrast, daily variations in maternal and fetal ...
Lévy F - - 1995
The respective roles of the main and accessory olfactory systems in the development of maternal behavior and selective suckling were investigated in parturient primiparous and multiparous ewes. Vomeronasal nerve section before parturition did not disturb either maternal behavior or maternal selectivity at suckling. By contrast, anosmia induced by zinc sulphate ...
Houghton D C - - 1995
We have investigated the effect of surgical disconnection of the fetal hypothalamus and pituitary (HPD) on generation of the daily rhythm in fetal plasma melatonin and PRL concentrations under long and short photoperiods. Fetal HPD or a sham operation was carried out at around 110 days gestation. Ewes carrying either ...
Jabbar G - - 1994
Two commercially available progestogen products for cattle, melengestrol acetate (MGA) and norgestomet (SMB), were evaluated for their ability to induce synchronized estrus in anovulatory ewes. Seasonally anestrous ewes (n = 232) were randomly assigned to one of seven treatments: 1) control (C); 2) MGA only (OMGA; .3 mg of MGA/d); ...
Guillery E N - - 1994
We have studied maturational changes in the kinetics of the proximal tubule Na+/H+ antiporter. Microvillus membrane vesicles were prepared from renal cortex of fetal and newborn lambs. Amiloride-sensitive uptake of 22Na+ by these vesicles was measured and Woolf-Augustinsson-Hofstee plots were used to determine the Michaelis constant (Km) and rate of ...
Prozesky L - - 1994
Previously published results of dosing trials, involving 82 ewes, revealed that 66% of the offspring of dams exposed to cultures of Diplodia maydis in the second trimester of pregnancy and 87% of lambs of ewes exposed in the third trimester, were born dead or died soon afterwards. Spongiform degeneration of ...
Buckrell B C - - 1994
A transcervical technique (the Guelph System for transcervical AI) was used to inseminate 2060 ewes on 65 farms (average 31 ewes, range 5 to 107) in Ontario, Canada, from October 1990 to September 1992, using previously frozen semen. Estrus was synchronized using progestagen pessaries and PMSG with median inseminations done ...
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