Duration of anestrus in Pramenka and Romanov ewes in Yugoslavia.

Jugular plasma progesterone was determined for two groups of native Yugoslavian ewes (Pramenka, Groups 1 and 2) and for a group of Romanov ewes (Group 3) from the end of January to late October in 1988. Ewes were pregnant until the end of March (pregnancy progesterone concentrations, 2.84 to 33 ng/mL). From the end of March to the beginning of July, progesterone concentration decreased (0 to .15 ng/mL). From early July to late October, progesterone concentrations increased. Progesterone concentrations were at their nadir near the summer solstice and increased significantly by early July in all three groups. The duration of anestrus was similar in Pramenka and Romanov ewes. In nonpregnant Pramenka ewes, the pattern of changes in plasma progesterone was similar to those seen in pregnant ewes except for an earlier decline with very low concentrations observed after mid-March.     

Pharmacokinetics of toltrazuril and its metabolites in pregnant and nonpregnant ewes and determination of their concentrations in milk,allantoic fluid,and newborn plasma

The objectives of this study were to determine the pharmacokinetics of toltrazuril and its metabolites in pregnant and nonpregnant ewes following a single oral dose and to determine the plasma concentrations of these compounds in milk, allantoic fluid, and newborn plasma. Eighteen healthy ewes were randomly divided into three groups (n = 6 each): pregnant ewes at 12–13 weeks of gestation (group A), nonpregnant ewes (group B), and pregnant ewes at 1–2 weeks before expected lambing date (group C). Ewes in all groups received a single oral dose of toltrazuril at 20 mg/kg body weight. In groups A and B, blood samples were collected at 1, 3, 5, 7, 9, 12, 15, 18 hr, every 6 hr to day 3, every 12 hr to day 7 and thereafter every 24 hr to day 14 post-toltrazuril administration. In group C, parturition was induced 24–36 hr after toltrazuril administration then milk, allantoic fluid, and newborn plasma samples were collected immediately after birth. Drug metabolites were assayed using ultra high-performance liquid chromatography–ultraviolet detection method (UHPLC-UV). The maximum concentration (C_max), area under the plasma concentration-time curve (AUC_0–t), AUC to 24 and 48 hr (AUC_0–24), and (AUC_0–48) were significantly higher in pregnant ewes. Longer apparent half-life (T_1/2), significantly higher apparent volume of distribution (Vd/F) and total clearance (Cl/F) were observed in nonpregnant ewes. The time to maximum plasma concentration (T_max), mean residence time (MRT) and elimination rate constant (K_el) were similar in both groups. The AUC_0–24 and AUC_0–48 were significantly higher in nonpregnant ewes. The AUC_0–t was significantly higher in pregnant ones. The ratio of plasma toltrazuril concentrations in ewes and toltrazuril concentrations in newborn lambs' plasma, allantoic fluid, and milk were 68%, 2.3%, and 5.3%, respectively. Results of this study showed that toltrazuril is well absorbed after a single oral dose in ewes with widespread distribution in different body tissues.     

Use of injectable vitamin E and selenium-vitamin E emulsion in ewes and suckling lambs to prevent nutritional muscular dystrophy

Forty-eight Blackbelly X Dorset, 27 Finnish, 26 Finnish X Dorset, 28 Rambouillet and 8 Dorset Suffolk-sired lambs were used in this experiment. Three weeks before lambing, one-half of the ewes received a selenium emulsion (Se-E) containing .05 mg selenium and 3.7 IU of vitamin E/kg body weight (BW). A 2 X 3 X 2 factorial arrangement was used; lambs from either treated or nontreated ewes were randomly assigned irrespective of breed to one of six treatment combinations consisting of 0 or .025 mg/kg BW selenium (Se) injected at birth or two .025 mg/kg BW Se injections, one at birth and one 2 to 3 wk later, and two levels of injectable Vitamin E (E; 0 and 100 IU) given at birth. Both lambs and ewes were provided access to 75% concentrate diets supplemented with Se and E at recommended NRC levels. Plasma activity of creatine phosphokinase (CPK) was highest at 1 d of age and exhibited decreases (P less than .001) over time. In lambs, the E injection tended to decrease plasma activity of CPK. Plasma glutathione peroxidase activity was lowest at 1 d of age and increased over the course of the experiment but was unaffected by treatments (P less than .05). Plasma tocopherol concentration decreased (P less than .01) with time, with E therapy tending to increase tocopherol concentration. Differences in mean plasma tocopherol concentrations among breeds were also observed (P less than .01). Selenium concentration increased over time and with the E injection (P less than .01). An interaction between ewe and lamb Se-E treatments also was observed (P less than .10), with nontreated lambs from nontreated ewes exhibiting lower Se concentrations than treated lambs from injected ewes. An increase in lamb plasma Se concentration was noted in response to Se-E treatments (P less than .001). In the ewes, plasma tocopherol concentration was lower while Se concentration was higher at 18 d than at 1 d postpartum (P less than .01 and P less than .001, respectively). Milk Se concentration was lower at 18 d than at 1 d (P less than .001) and was higher (P less than .10) in Se-E-treated ewes.     

Influence of reproductive state on pituitary-adrenal activity in the ewe.

Plasma corticosteroid concentrations are altered in pregnancy, during the reproductive cycle and by ovariectomy in many species. This study was designed to examine basal ACTH and cortisol in ewes of four different reproductive statuses: ovariectomized, nonpregnant cycling, nonpregnant noncycling, and pregnant. Blood samples were drawn every 4 hr for 48 hr from ewes during quiet, undisturbed conditions and analyzed for plasma ACTH, cortisol and progesterone concentrations. There were no significant changes in ACTH, cortisol or progesterone over time. Mean progesterone concentrations were significantly greater in the pregnant ewes than in all other ewes, and were greater in cycling ewes than noncycling or ovariectomized ewes. Mean ACTH was significantly greater in pregnant ewes than noncycling ewes, and mean cortisol was significantly greater in cycling ewes than in nonpregnant cycling or noncycling ewes. Ovariectomized ewes also had significantly greater mean cortisol concentrations than cycling ewes. The results demonstrate that there is an increase in basal ACTH and cortisol in ovine pregnancy.     

The stress caused by laparoscopy in sheep and its alleviation

AIM: To determine the plasma cortisol response to laparoscopy in ewes and investigate means of reducing it. METHODS: Ewes without lambs at foot (n=40) were subjected to one of three control or one laparoscopy treatments (n=10 ewes/treatment), being: no restraint or drugs; acepromazine maleate (ACP) control and no restraint; ACP and restraint in a cradle for 5 min; and laparoscopy following ACP. Additional ewes with lambs at foot (n=30) were subjected to: laparoscopy following ACP; laparoscopy following ACP and ketoprofen; and laparoscopy following detomidine. Drugs were injected 20 min before treatment, after a first blood sample had been taken. Blood samples were taken by jugular venepuncture from the ewes 20 min before treatment and at 20, 40, 60, 90, 120, 150 and 180 min after treatment, while all ewes were held in a pen. Plasma was harvested and assayed for its concentration of cortisol. RESULTS: Plasma cortisol concentrations (PCC) remained constant in ewes in the control restraint group for 80 min. In ewes given ACP, PCC increased for the first 20 min after treatment but then returned to pre-treatment concentrations. PCC of ewes given ACP and restrained in a cradle were elevated above pre-treatment concentrations for 90 min. PCC in ewes subjected to laparoscopy following sedation with ACP increased to a peak at 40 min and returned to pre-treatment concentrations after 60 (with lambs) or 120 (without lambs) min. When ACP and ketoprofen were given before laparoscopy, PCC peaked at 20 min and returned to pre-treatment concentrations by 40 min. PCC of ewes given detomidine before laparoscopy remained at pre-treatment concentrations throughout. PCC of ewes subjected to laparoscopy with ACP sedation only were greater than those of control restraint, ACP control, and ewes subjected to laparoscopy after being given ketoprofen or detomidine between 20 and 60 min after treatment. PCC of ewes subjected to laparoscopy were greater than those of control ewes placed in a cradle at 20 and 40 min. PCC of ewes given ketoprofen were lower than those of ewes subject to laparoscopy following ACP. CONCLUSIONS: Laparoscopy, even after sedation with ACP, caused some distress in ewes, as evidenced by increased plasma cortisol levels. Plasma cortisol response was alleviated by the administration of ketoprofen and eliminated by detomidine, probably because of both analgesic and sedative effects of the latter drug.     

Plasma metabolite concentrations and hepatic enzyme activities in pregnant Romney ewes with restricted feeding

Plasma metabolite concentrations and activities of enzymes related to energy metabolism in plasma, peripheral leukocytes and liver of pregnant Romney ewes with restricted feeding were measured to assess those metabolites and enzymes as indicators for evaluating metabolic conditions in the ewes. The body weights and plasma lactate concentrations of the low-feeding ewes (about 1.0 times maintenance) were significantly lower than those of the high-feeding ewes (about 1.5 times maintenance). There were no significant differences in plasma protein, glucose, triglyceride, cholesterol, pyruvate and immunoreactive insulin concentrations and plasma and leukocyte enzyme activities between both groups. Hepatic malate dehydrogenase activities were significantly higher and hexokinase activities were significantly lower in the low-feeding ewes than in the high-feeding ewes. Restricted feeding could maintain pregnancy and some plasma metabolites and peripheral leukocyte enzymes may be useful indicators for evaluating metabolic changes in ewes.     

Effect of vitamin D supplementation during pregnancy on the vitamin D status of ewes and their lambs

Pregnant ewes were injected intramuscularly with 300,000 iu of vitamin D3 in a water miscible vehicle either 10, seven or four weeks before the expected lambing date and the effects on plasma concentrations of 25-hydroxyvitamin D3 were monitored. The concentrations increased quickly and remained high at parturition but at no time were they outside the normal physiological range. The concentrations in the plasma of the newborn lambs were higher than in uninjected controls and were well correlated with the concentrations in their mothers. Dosing pregnant ewes with 300,000 iu of vitamin D3 in a rapidly available form, approximately two months before lambing, provided a safe means of increasing the vitamin D status of the ewe and the newborn lamb by preventing the seasonally low concentrations of 25-hydroxyvitamin D3.     

Combined xylazine and ketamine as an analgesic regimen in sheep

OBJECTIVE: To determine whether low dose xylazine with ketamine reduces the concentrations of cortisol and prolactin in sheep postoperatively and to characterise the effects of the drugs on behaviour during recovery. DESIGN: Analysis of variance was used to compare the effects of anaesthesia, surgery and combined ketamine/xylazine treatment on the plasma cortisol and prolactin concentrations and on behavioural variables in pregnant ewes subjected to abdominal surgery. PROCEDURE: Twelve ewes were randomly assigned to receive either ketamine/xylazine or placebo in association with anaesthesia and surgery. Both groups of ewes underwent anaesthesia alone followed a week later by anaesthesia with laparotomy and hysterotomy. Plasma cortisol and prolactin concentrations were assayed during these procedures and for 5 days afterwards. Behavioural observations were made remotely during recovery from anaesthesia and anaesthesia plus surgery. RESULTS: The concentrations of cortisol in the plasma of pregnant ewes undergoing surgery were increased by preoperative handling and the onset of thiopentone/halothane anaesthesia, with a further increase during surgery (P = 0.033). Cortisol concentrations decreased over the first four postoperative hours (P = 0.029) and were normal by 24 h. The drug treatment did not affect the immediate responses of ewes to anaesthesia or surgery, although treated ewes had lower cortisol concentrations than saline-treated controls over the first five postoperative days (P = 0.018). Prolactin concentrations increased in response to anaesthesia (P = 0.047), but were not affected by surgery or the drug treatment. Drug-treated ewes had prolonged sleeping time after surgery (P = 0.002), but they took no longer to stand than saline-treated controls and required fewer attempts to stand successfully (P = 0.025). CONCLUSION: At the doses used, ketamine and xylazine did not mitigate the immediate endocrine consequences of surgery but the behavioural data provide a basis for further investigations that may lead to improvements in analgesic treatments.     

Elimination of tilmicosin in lactating ewes.

Tilmicosin was injected subcutaneously to lactating ewes once at a dose of 10 mg kg-1 b.wt. to determine its plasma, milk, urine and ruminal juice concentrations. Tilmicosin could be detected in all those fluids 30 minutes after injection. Milk and urine concentrations were higher than those of plasma and ruminal juice. The drug was detectable in milk, urine and plasma for 9, 4 and 3 days after injection, respectively. No amount of tilmicosin could be detected in ruminal juice 12 hours following administration. The mean peak concentration of tilmicosin in plasma and milk (Cmax) were 1.29 and 9.5 micrograms ml-1 and were obtained at (Tmax) 5.235 and 15.093 hours, respectively. The drug was slowly eliminated from plasma and milk as indicated by its long half-life (t1/2el) of 15.4 and 26.2 hours, respectively. The mean binding of tilmicosin to plasma and milk proteins in vitro was 16.8% and 26.8%, respectively. The drug was not bound to ruminal juice at any extent. The rate of tilmicosin renal clearance revealed that it was correspondingly increased with higher blood concentrations. While creatinine clearance showed no significant change after tilmicosin administration. The ratio (fractional clearance) between tilmicosin renal clearance to creatinine clearance was less than one indicating that the glomerular filtration is the main pathway of elimination through kidneys. The rate of ruminal gas fermentation in ewes was inhibited after subcutaneous injection of tilmicosin at a dose of 10 mg kg-1 b.wt. The tested samples taken at different time intervals from the rumen of ewes showed a subsequent reduction in the rate of fermentation as compared to control samples. The reduction was correspondingly increased with the increase of tilmicosin concentration in ruminal juice and returned to normal thereafter.     

The behavior of lactogenic and steroid hormones in the blood of Awassi ewes in Syria during lactation

The concentrations of lactogenic hormones (prolactin--PRL, growth hormone--GH, insulin-like growth factor I--IGF-I) and steroid hormones (progesterone--PG, estradiol--E2) were determined by RIA in the blood plasma of 8 lactating ewes (3 with twins) and compared with that of 3 non-lactating cycling ewes of the same age. All animals live in a flock of 30 Awassi sheep under identical conditions in Syria. The lactation period (192 +/- 25 days) is divided to a suckling period (until day 63) and a hand milking period (2 fold daily) with different levels of milk production (near 2 litres/day in the former, decreasing from 0.8 to 0.1 litre/day in the latter). During the suckling period the concentrations of steroid hormones in the blood plasma are lower, these of lactogenic hormones are higher of lactating than of non-lactating ewes. During the milking period only the concentrations of E2, PRL and IGF-I in the blood plasma of lactating animals are lower than in non-lactating ewes. But, during this time more and more seasonal influences (increasing day length and temperature) overwhelm the influence of lactation on the hormone secretion. Suckling of twins is accompanied with higher levels of E2, PRL and IGF-I in the blood plasma of their mothers than suckling of single lambs. During the lactation period a strong correlation exists between milk yield and the level of GH (r = 0.85) and IGF-I (r = 0.71), a smaller correlations to the level of E2 (r = 0.49) in the blood plasma of the lactating ewes. During the suckling period the milk yield is influenced positively by PRL (r = 0.77) and GH (r = 0.68), but negatively by PG (r = -0.76). During the milking period the milk yield is determined extensively by the level of IGF-I (r = 0.89) in the blood plasma. The concentrations of the analyzed hormones in the blood plasma correlate always positively together.     

Pharmacokinetics of chlortetracycline in maternal plasma and in fetal tissues following oral administration to pregnant ewes

The purpose of this study was to determine if concentrations of chlortetracycline could be detected in fetal plasma or tissues after administering an oral dose of chlortetracycline (CTC; 500 mg/head/day) reported to be effective in controlling Campylobacter spp. abortions. Five pregnant ewes were administered 250 mg/head twice a day (total dose 500 mg/hd/d) for 7 days. On the beginning of day 7, intravenous catheters were surgically implanted or inserted into the fetus and dam. Plasma samples were collected from the ewe and fetus at various time points before and up to 36 hr after the last dose of CTC. All ewes were then sacrificed, and tissues were harvested from the fetus for drug analysis. Concentrations of CTC in maternal plasma were consistent with our previous study and below the minimum inhibitory concentration of Campylobacter abortion isolates. Concentrations of CTC were below the limit of detection in three of five fetal plasma samples and all of the placenta, amniotic fluid, and fetal stomach contents. Low concentrations were detectable in fetal kidney and liver, suggesting that CTC reaches the fetus, although at a variable and low ratio when compared to maternal concentrations.     

Pancreatic insulin release and peripheral insulin sensitivity in German black headed mutton and Finish Landrace ewes: evaluation of the role of insulin resistance in the susceptibility to ovine pregnancy toxemia

German black headed mutton (GBM) ewes are recognized as being highly susceptible to ovine pregnancy toxemia (OPT). The present trial was performed to evaluate whether a breed-dependent gestational diabetes mellitus-like insulin resistance during late pregnancy might be responsible for the high incidence of OPT in the GBM breed. Modified frequently sampled intravenous glucose tolerance tests (300 mg glucose and 0.03 IU insulin per kg of BW) were performed during mid and late pregnancy, the periparturient, and the dry period in polytocous 3.5-yr-old GBM and Finnish Landrace (FL) ewes fed according to their requirements. The corresponding blood samples were analyzed for plasma concentrations of glucose, insulin, nonesterified fatty acids (NEFAs) and β-hydroxybutyrate (β-HB). In addition, the baseline plasma cortisol concentrations were determined during late pregnancy. The BW gain during pregnancy and the rearing success did not differ between the GBM and FL ewes. In both breeds, late pregnancy was associated with decreased basal plasma glucose concentrations and enhanced glucose disposal, as well as elevated baseline β-HB values. Only in the GBM ewes did the plasma NEFA concentrations increase significantly during advancing pregnancy. Moreover, significantly higher baseline plasma NEFA concentrations as well as lower (P < 0.05) basal plasma glucose values were recorded during late pregnancy in the GBM than in the FL ewes. The first-phase insulin secretion, the peripheral insulin sensitivity, and the baseline plasma cortisol values did not differ between both breeds during late pregnancy. It is concluded that increased lipolysis during late pregnancy is a characteristic of the GBM breed. Moreover, elevated plasma NEFA concentrations may contribute to impaired pancreatic insulin response and peripheral insulin resistance in GBM ewes and thus promote OPT.     

Stimulation of calcium absorption and reduction in susceptibility to fasting-induced hypocalcaemia in pregnant ewes fed vegetable oil

AIM: To test the hypothesis that susceptibility to fasting-induced hypocalcaemia could be reduced by prior stimulation of the ability of late-pregnant ewes to absorb calcium (Ca) from the gastrointestinal tract (GIT) by feeding a vegetable oil supplement. The supplement was expected to decrease the availability of the Ca supplied from a pasture diet, and stimulate the animals' homeostatic system. METHODS: Mature ewes pregnant with twins (n=28) and grazing at pasture, were randomly allocated to Treated or Control groups, 6 weeks prior to their expected date of parturition (Day 0). Treated ewes (n=14) were drenched with 25 ml soya bean oil twice daily for 3 weeks. Plasma Ca concentrations were determined on Days 0, 8, and immediately before and after a 20-hour fast that began on Day 21, which was intended to simulate the reduced feed intakes that occur on the day of parturition. An index of the ewes' ability to absorb Ca from the GIT was obtained using orally dosed strontium (Sr) as a tracer and the extent of Ca mobilisation from bone was assessed by measuring hydroxyproline concentrations in plasma before fasting on Day 21. RESULTS: Plasma Ca concentrations were significantly higher in Treated than Control ewes after fasting (p0.001). The Ca absorption index was also higher in Treated than Control ewes at the end of the 3-week treatment period (p=0.014), but degree of bone mobilisation assessed by concentration of hydroxyproline in plasma did not differ significantly between groups. CONCLUSION: Susceptibility of late-pregnant ewes to fasting-induced hypocalcaemia was reduced using a soya bean oil supplement. The inclusion of one or more dietary ingredients capable of binding or forming complexes specifically with Ca in the diet of late pregnant ruminants may provide a novel, practical method of reducing periparturient hypocalcaemia.     

Attenuation by an opioid agonist of the oestradiol-induced LH surge in anoestrous ewes and its reversal by naloxone

The effects of a potent opioid peptide agonist [D-ala2-Phe4, Met(0)ol5-enkephalin (FK 33-824) on the magnitude of the oestradiol-induced LH surge and on basal plasma LH concentrations were examined in intact and chronically-ovariectomized ewes during the late-anoestrous period. In intact ewes, treatment with FK 33-824 (0.5 mg i.v. every 3 hr) for a 24 hr period commencing at the time of oestradiol-17 beta administration (25 micrograms i.m. bolus) was associated with non-significant 65% reduction in the peak plasma LH level observed and a significant (P less than 0.05) 58% reduction in the total amount of LH released during the surge (calculated from the area under the curve). Concurrent treatment with the opioid antagonist naloxone (10 mg i.v. every 3 hr) partially reversed this suppressive effect on the magnitude of the LH-surge. In ovariectomized ewes no significant effects on the oestradiol-induced LH surge of either FK 38-824 alone or FK 33-824 in combination with naloxone were observed. Administration of FK 33-824 at a 6-fold higher dose rate (0.5 mg every 30 min) failed to modify basal plasma LH concentration in intact ewes. In ovariectomized ewes, however, a significant (P less than 0.05) 25% fall in basal plasma LH was observed, an effect which was completely reversed by combined treatment with naloxone (10 mg every 30 min). These results support the conclusion that endogenous opioid peptides may contribute to the neuroendocrine mechanism through which oestradiol promotes a preovulatory-like surge in the anoestrous ewe.     

Concentrations of ovarian and pituitary hormones following prostaglandin F2 alpha-induced luteal regression in ewes varies with day of the estrous cycle at treatment

Prostaglandin F2 alpha (PGF2 alpha) was injected on d 5, 8 or 11 postestrus in ewes to determine how stage of the estrous cycle would affect PGF2 alpha-induced changes in concentrations of ovarian and pituitary hormones and intervals to the onset of estrus and the preovulatory surge of luteinizing hormone (LH). Initial concentrations of progesterone and average values during the 12 h after PGF2 alpha were related positively to the day of cycle on which PGF2 alpha was administered. Patterns of decline in progesterone after injection of PGF2 alpha were similar among the 3 d. Concentrations of LH in plasma increased in a similar manner from 0 to 12 h in all ewes. After 12 h LH continued to increase, plateaued or declined in ewes treated on d 5, 8 or 11, respectively. Initial concentrations of follicle stimulating hormone (FSH) in plasma were related positively to day of treatment. After treatment with PGF2 alpha, FSH increased within 2 h on d 5 but declined by that time on d 8 or 11. Concentrations of estradiol following treatment did not vary with day. The onset of estrus and the preovulatory surge of LH occurred at 36 and 35, 40 and 45, and 48 and greater than 48 h in ewes treated on d 5, 8 or 11, respectively. It is concluded that: 1) the initial increase in LH is dependent on a decrease in plasma progesterone and 2) differences in patterns of secretion of gonadotropins before the preovulatory surge of LH might be caused by differences in progesterone or progesterone:-estradiol ratio when luteal regression is induced on different days of the estrous cycle.     

Chronic heat stress and prenatal development in sheep: I. Conceptus growth and maternal plasma hormones and metabolites

Pregnant ewes were chronically exposed to thermoneutral (TN; 20 degrees C, 30% relative humidity) or hot (H; 40 degrees C 9 h/d, 30 degrees C 15 h/d, 40% relative humidity) environments between d 64 and 136 to 141 of pregnancy. They were sampled for blood at 14-d intervals during this period for measurement of plasma metabolites and hormones, then slaughtered and dissected to measure conceptus weights, dimensions and fetal organ weights. Rectal temperatures of H ewes were elevated .3 to 1.0 C degrees above those of TN ewes throughout the experiment. Voluntary feed intakes were not altered by heat exposure except after 120 d of pregnancy, when feed intake was about 25% lower (P less than .10) by H than by TN ewes. Blood 3-hydroxybutyrate concentrations were not affected by heat, but plasma glucose concentrations were greater in H than in TN animals after 120 d (P less than .05). Placental weight, reduced by 54% (P less than .001) by heat exposure of ewes, was correlated positively with fetal weight and correlated negatively with fetal/placental weight ratio, fetal brain/liver weight ratio and fetal relative heart weight. Late in pregnancy, plasma concentrations of progesterone, cortisol and placental lactogen were reduced (P less than .01) in H ewes, whereas triiodothyronine levels were markedly lower (P less than .03) at all stages of pregnancy. Plasma concentrations of prolactin were elevated dramatically (P less than .01) and a modest increase (P less than .03) in somatotropin levels was recorded in H ewes. These results are consistent with our hypothesis that heat-induced fetal growth retardation is secondary to a primary reduction in placental growth; this could be mediated partly by reduced peripheral activity of thyroid hormones. Heat-induced reductions in secretion of progesterone and ovine placental lactogen more likely were a consequence than a cause of placental stunting.     

Acute phase protein response of ewes and the release of PGFM in relation to uterine involution and the presence of intrauterine bacteria.

The rate of uterine involution postpartum was monitored in 13 suckling mule ewes by using radio-opaque markers and radiography, and each ewe was also monitored for intrauterine bacterial contamination during the first week, using a sterile guarded swab. Peripheral plasma or serum concentrations of haptoglobin, seromucoid, ceruloplasmin and 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) were measured up to six weeks postpartum. The maximum reduction in the length of the uterine body and in the diameters of the horns occurred by 28 days postpartum, except in one ewe in which the size of the uterus continued to decrease for 42 days. Four ewes were positive for intrauterine bacterial contamination; Escherichia coli, clostridial species, Staphylococcus aureus, Streptococcus uberis and Enterococcus species were isolated in pure or mixed culture. The presence of intrauterine bacteria did not affect the time for the completion of uterine involution. No bacteria were isolated from the ewe in which involution was delayed, but it had a different acute phase protein response and was therefore excluded from further analyses. In the remaining 12 ewes the mean postpartum haptoglobin response increased, with peak concentrations occurring on day 1, and decreased slowly as uterine involution progressed, but the four contaminated ewes had a significantly greater response. There was no difference between the prepartum and postpartum concentrations of seromucoid in the eight sterile ewes, but significant increases were observed in the contaminated group; the concentrations of ceruloplasmin did not vary in either group. The concentrations of PGFM were higher during the early postpartum period in the ewes with contaminated uteri.     

Effects of exogenous estradiol and progesterone on plasma concentrations of leptin in ewes in non-breeding season

Estradiol and progesterone may play a role in controlling leptin secretion by utilizing their receptors in adipocytes and the genomic mechanisms of the leptin gene. This study was conducted to evaluate the effects of exogenous sex steroids on the blood leptin concentrations in ewes in the non-breeding season. Multiparous ewes were fed to maintenance level for their live weights. Blood samples were collected at 12-h intervals from Days -3 to -1 to determine the basal leptin levels (pre-injection period). From Day 0 to Day 5 (injection period), blood sampling continued at 12-h intervals, and the ewes were injected intramuscularly at 24-h intervals with oil, 50 mg progesterone in oil, 1 mg of estradiol in oil, or both steroids in oil. Leptin was measured using a sensitive and specific radioimmunoassay based on recombinant bovine leptin. Overall, plasma concentrations of leptin were not affected by any of the steroid treatments, and there were no differences in the value of leptin between the pre-injection and injection periods among the 4 groups. Therefore, the exogenous estrogen and progesterone used in this study do not have a strong effect on the blood leptin concentrations of ewes in the non-breeding season.     

Intrauterine bacterial inoculation and level of dietary methionine alter amino acid metabolism in nulliparous yearling ewes

Using an intrauterine bacterial inoculation method, our objective was to determine the effects of acute sepsis and level of dietary metabolizable Met (MM) on splanchnic metabolism of AA in ewes. Twenty-four nulliparous yearling Rambouillet-cross ewes (initial BW = 65.1 +/- 0.6 kg), surgically fitted with chronic-indwelling catheters in hepatic and portal veins, a mesenteric vein and artery, and the uterine lumen, were assigned to a 2 x 2 factorial arrangement of treatments. Factors were intrauterine bacterial inoculation (noninoculated vs. inoculated) and level of MM [low (2.28 g/d) vs. high (3.91 g/d)]. Beginning 12 h before sampling, inoculated and noninoculated ewes received 10-mL intrauterine infusions of Escherichia coli (9.69 x 10(11) cfu) + Arcanobacterium pyogenes (2.76 x 10(12) cfu) and of sterile saline, respectively. Uterine infection was induced in ewes that received intrauterine bacterial inoculations, but not in ewes infused with sterile saline. Bacterial inoculation resulted in increased hepatic release and plasma concentrations of aromatic AA used for acute-phase protein synthesis, increased hepatic removal and decreased plasma concentrations of AA used for glutathione synthesis, and decreased plasma concentrations of some gluconeogenic and acetogenic AA used for glucose recycling and anaerobic energy production, respectively (P < 0.05). In ewes fed high-MM diets, compared with low-MM diets, a consistent net hepatic uptake of Phe occurred throughout the sampling period, more Asp was released from the portal-drained viscera, and hepatic vein glucose concentrations were greater (P < 0.05). We conclude that Met seemed to be limiting in low-MM ewes, and as such, would continue to be limiting during sepsis. However, additional MM, in excess of the dietary requirement, would not necessarily result in a benefit to ewes experiencing acute sepsis.     

Uterine environment as a regulator of birth weight and body dimensions of newborn lambs

Pure-bred embryos were transferred within and reciprocally between large (Suffolk) and small (Cheviot) breeds of sheep to establish 4 treatment groups: SinS (Suffolk embryos in Suffolk dams), SinC (Suffolk embryos in Cheviot dams), CinS (Cheviot embryos in Suffolk dams), and CinC (Cheviot embryos in Cheviot dams). The recipient ewes carried single fetuses to term. The maternal plasma concentrations of ovine placental lactogen (oPL), progesterone, IGF-1, FFA, and glucose were measured on d 50, 90, 120, and 140 of pregnancy. Birth weight, body dimensions, and placental characteristics of lambs were recorded at birth. There was a recipient ewe breed × lamb breed × time interaction for the concentration of oPL (P = 0.03), but no such interaction was observed for progesterone (P = 0.42), IGF-1 (P = 0.57), glucose (P = 0.36), or FFA (P = 0.72). There were no differences in oPL (P = 0.28) and progesterone (P = 0.34) concentrations between SinC and SinS ewes. The concentrations of FFA on d 140 (P = 0.008), and those of glucose on d 50 (P = 0.02) and 120 (P = 0.01), were greater in SinC ewes than in SinS ewes. The ewes in CinS had less FFA concentration (P = 0.002) at all time points than CinC ewes. The concentrations of IGF-1 on d 90 were greater (P = 0.004) in CinS ewes than CinC ewes, but did not differ (P = 0.16) on d 50, 120, and 140. The concentrations of glucose on d 50 (P = 0.001), 90 (P = 0.03), and 140 (P = 0.03) were less in CinS ewes compared with CinC ewes. The birth weight of SinC lambs (5.04 ± 0.20 kg) was lighter (P = 0.001) than SinS lambs (5.94 ± 0.19 kg), and body dimensions of SinC lambs were smaller (P = 0.01) than SinS lambs. Neither birth weight nor the body dimensions of CinS lambs differed (P = 0.24) from CinC lambs. Cotyledon number was reduced (P = 0.04) in the CinS (57.5 ± 6.3) compared with the SinS group (74.2 ± 5.9), whereas mean cotyledon weight in CinS (2.42 ± 0.20 g) was greater (P = 0.02) than SinS (1.74 ± 0.21 g). It was concluded that the large genotype lambs were lighter and smaller when born to small genotype dams; however, the birth weight or body dimensions of small genotype lambs did not differ when born to large genotype dams. This study suggests that plasma oPL, progesterone, IGF-1, FFA, and glucose concentrations at different times throughout pregnancy reflect the regulatory effect of the uterine environment on the development of the fetus.