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At least 163 records · Page 9Linked to original sources
PubMed2003

Cutaneous hypersensitivity reactions to Psoroptes ovis and Der p 1 in sheep previously infested with P. ovis--the sheep scab mite.

We have previously shown that infestation with Psoroptes ovis induces an IgE response and intense tissue eosinophilia, typical of a Type I hypersensitivity response [Parasite Immunol. 22 (2000) 407]. Intradermal tests (IDSTs) suggest that there are also delayed and Arthus-type responses to this parasite. In order to study the nature of ovine cutaneous reactions to P. ovis, naïve controls and experimentally infested sheep (n = 5) were challenged intradermally with mite antigen. Challenge elicited immediate (P < 0.001) and delayed (P < 0.005) wheal reactions in sensitised sheep. At 6 (P < 0.02) and 30 h (P < 0.001) the predominant infiltrating cells were eosinophils. To explore the role of circulating antibodies, naïve sheep (n = 5) were subjected to Prausnitz-Kustner (PK) tests. These elicited immediate (P < 0.02) but not delayed wheal reactions. At 6 h eosinophils (P < 0.001) dominated the infiltrate. These results suggest that P. ovis allergens provoke an IgE-dependent immediate and late phase response and a cell-mediated eosinophil-rich delayed-type hypersensitivity response (ER-DTH).

Animals↗
PubMed1998

The incidence of sheep strike by Lucilia sericata on sheep farms in Britain: a simulation model.

Using a combination of a temperature-dependent simulation of the population dynamics of Lucilia sericata and a logistic model of sheep susceptibility, based on patterns of faecal soiling, fleece length and fleece humidity, a deterministic simulation model has been constructed to predict the incidence of sheep strike by L. sericata on lambs and ewes in Britain. Strikes are assigned to individual sheep in the flock according to a negative binomial distribution. The model shows that the majority of the first strikes of the season occur equally on ewes and lambs, when ewe fleeces are long and before lamb susceptibility increases though faecal soiling. With each subsequent generation of gravid blowflies, however, a greater proportion of strikes occur on lambs, while the number of strikes observed on ewes remains relatively consistent throughout the season. The increase in strike of lambs is due to the seasonal increase in lamb faecal soiling, associated with rising helminth infections and lamb fleece growth. The model shows that at the beginning of the season the incidence of strike is limited by the low number of flies present: towards the end of seasons, however, the blowfly population had grown large enough for the number of strikes to be limited by the number of susceptible ewes and lambs. The model shows that the seasonal incidence of strike is highly sensitive to the interactions between temperature, rainfall and would length. Strike was most prevalent under warm, wet conditions. However, there is a critical period during spring, where the short fleeces of lambs and ewes, in the latter case due to shearing, results in the desiccation of egg batches. If this coincides with dry conditions, the high levels of mortality result in suppression of the fly population and a reduction in the subsequent incidence of strike.

Animals↗
PubMed1975

[Phosphoric acid ester preparations used in cattle, swine and sheep with special reference to cholinesterase activity. 4. Use of phosphoric acid esters and their effect on acetylcholinesterase activity in sheep].

The use of organophosphorus preparations for the control of ectoparasites and endoparasites of sheep, particularly systemic application, is discussed. Experiments on 13 groups of sheep with five preparations produced in the German Democratic Republic in various formulations and concentrations showed that external application had good contact activity, but little was absorbed. Acetylcholinesterase activity was not inhibited, except by pour-on application of doses several times the normal dose. The preparations were arranged in order of cholinesterase inhibition. In contrast to cattle, diminished cholinesterase activity was unreliable as in indicator of systemic toxicity of organophosphorus preparations in sheep.

Acetylcholinesterase↗
PubMed1984

Evaluation of a radial immunodiffusion test for diagnosing brucellosis in sheep and its possible value for differentiating infected from Brucella melitensis REV 1 vaccinated sheep.

The efficiency of 4 serological test: Rose Bengal (RB), complement fixation (CF), gel diffusion (GD) and radial immunodiffusion (RID) for diagnosing Brucellosis in sheep was compared. RID and CF were also used to evaluate sheep serological response following REV 1 vaccination. Crude smooth lipopolysaccharide (LPS-S) and Polysaccharide B antigens obtained from B. melitensis 16 M were used in GD and RID tests respectively. In experiment 1, two hundred and sixty five sera from adult unvaccinated sheep were studied. The animals used belonged to 4 different flocks, in which was bacteriologically proved the existence of B. melitensis infection. RB positive reaction was obtained in 122 sera being 100, 87 and 91 of these, positive to CF, GD and RID respectively. In experiment 2, one hundred and one ewes from 5 to 10 months of age (and CF negative) were subcutaneously inoculated with 2.10(9) viable Rev 1 organisms. All animals were bled at 1, 2, 5, 10, 20, 24, 28 and 52 weeks after being vaccinated, and their serological response to CF and RID tests was studied. The percentage of CF reactors between the 24th and the 52nd weeks decreased from about 30% to less than 8%. The RID reactors in weeks 24 and 52 were 1% and 0% respectively when a concentration of 15 micrograms of Polysaccharide B per ml of gel was used.

Animals↗
PubMed1994

Inhibitory activity of soluble material from sheep eosinophils for sheep complement.

Soluble material from frozen and thawed sheep eosinophils and sonicated extracts of eosinophils or their granules inhibited the alternative activation pathway dependent action of sheep complement for human erythrocytes sensitized by sheep antibody. Sephadex G-50 fractions of the sonicated eosinophil and granule extracts showed that inhibitory activity was associated with the void volume fraction, the fraction possessing the eosinophil peroxidase activity.

Animals↗
PubMed1976

Studies on the glycolipids of sheep thymus and of normal and concanavalin A-stimulated sheep peripheral lymphocytes.

The neutral glycolipids and gangliosides of sheep thymus and of sheep peripheral lymphocytes were compared. The patterns of both of these major classes of glycolipids were more complex in thymus than in the lymphocytes. The incorporation of radioactivity from D-[1-14C]galactose into the individual glycolipids of control and concanavalin A-stimulated sheep peripheral lymphocytes was also studied. A marked enhancement of incorporation into trihexosylceramide and an alteration of the pattern of incorporation into gangliosides were noted in the mitogen-treated cells. The results suggest that significant alterations of glycolipid composition and metabolism may occur during at least certain stages of lymphocyte differentiation.

Animals↗
PubMed1987

Carbonic anhydrase activity in the blood of adult sheep, fetal sheep and lambs.

The activity of carbonic anhydrase (E.C.4.2.1.1) (CA) has been measured in the blood of adult and fetal sheep and lambs. The mean activity in adult sheep was 0.89 enzyme units (EU) per 100 micrograms of Hb. The activity in fetal sheep aged 90 days was just below 20% of this and in fetuses near full term was just under 40% of the mean adult level. The regression line gave an increase of CA activity (per 100 micrograms Hb) of 0.004 EU/day. The appearance of CA in fetal blood normally occurred before any detectable production of adult Hb. One aberrant fetus showed early development of the adult pattern in the red cells, having adult type Hb and adult levels of CA during the period of 116-128 days of fetal age. In the period after birth the CA level in the blood rose rapidly, reaching the adult level 30 days after birth. During this period activity per 100 micrograms HB increased by 0.014 EU/day, significantly faster than during fetal life.

Aging↗
PubMed1988

Adrenergic neurons in sheep brain demonstrated by immunohistochemistry with antibodies to phenylethanolamine N-methyltransferase (PNMT) and dopamine-beta-hydroxylase (DBH): absence of the C1 cell group in the sheep brain.

Using immunohistochemistry with specific antisera against dopamine-beta-hydroxylase and phenylethanolamine N-methyltransferase, we present the first description of the adrenergic structures of the sheep medulla oblongata. Dopamine-beta-hydroxylase-immunoreactive perikarya in the sheep brain are localized as described in the rodents (A1 and A2 groups) but their distribution is characterized by only one phenylethanolamine N-methyltransferase immunoreactive cell body group, found in the nucleus tractus solitarius. This group corresponds to the C2 group previously described in the rat, but neither group C1 nor group C3 are found in the sheep with our method. Compared with rodents or primates, this animal presents a different pattern of central adrenergic innervation and could be an alternative model to study the central role of adrenaline in various physiological functions as different as swallowing or reproduction.

Adrenergic Fibers↗
PubMed2004

A kinematic, kinetic and electromyographic comparison of stooped sheep shearing techniques and shearing with a sheep manipulator.

Traditional sheep shearing methods require workers to adopt postures where the trunk is approximately horizontal and held in that position against gravity for long periods of time. The objective of this study was to examine the biomechanics of stooped shearing techniques and to compare the effectiveness of a new sheep manipulator in reducing the frequency of these postures and the changes in low back forces and electromyographic (EMG) activity. Five male shearers were filmed using three video cameras and EMG and three-dimensional (3D) kinematic data were derived during seven segments of the shearing action. Kinematic data were used to calculate the L5/S1 compressive and shear forces using the 3D Static Strength Prediction Program(TM). Results showed the low back forces in stooped shearing were typically between 2200 and 3000N. Also, the sheep manipulator effectively allowed the shearers to maintain a more upright posture (mean trunk angle >65 degrees) which decreased the compressive (maximum <1350N) and shear (maximum <260N) forces at L5/S1.

Animals↗
PubMed2005

Enrichment of cheeses manufactured from cow's and sheep's milk blends with sheep-like species-related alkylphenols.

Enhancement of concentrations of species-related sheep-like alkylphenols, p- and m-cresols and 3- and 4-ethylphenols, in experimental Manchego-type cheeses manufactured from cow's and sheep's milk blends (80:20) by using arylsulfatases was investigated. A food-grade arylsulfatase from Aspergillus oryzae (ATCC 20719) was produced using a stimulatory medium, and crude dried cells were used as the enzyme source. Exogenous arylsulfatases from Helix pomatia and A. oryzae were added to cheese curd, and the amounts of species-related alkylphenols were measured. Arylsulfatase from H. pomatia released limited amounts of alkylphenols in the cheese only when used at a high level. Arylsulfatase from A. oryzae released substantial amounts of alkylphenols during 2 months of ripening. The concentrations of alkylphenols in A. oryzae arylsulfatase-treated cheese were comparable to the previously reported levels present in aged Manchego-type cheeses manufactured from pure sheep's milk.

Animals↗
PubMed1977

Hemoglobin switching in sheep and goats: induction of hemoglobin C synthesis in cultures of sheep fetal erythroid cells.

Synthesis of HbF (alpha2gamma2) is replaced by synthesis of Hb A (alpha2betaA2) shortly before birth in sheep homozygous for the betaA globin chain whereas Hb C (alpha2betaC2) is produced transiently during the neonatal period. We have obtained a Hb F-to-Hb C switch by generating erythroid colonies at high erythropoietin concentration in plasma clot cultures of mid-gestation fetal bone marrow or liver. Furthermore, high erythropoietin concentration appeared specifically to activate the gene for betaC and not those for betaA or betaB globin in colonies grown from cells of an animal heterozygous for the betaA and betaB genes. Erythropoietic stress in the form of periodic bleeding or erythropoietin injection in utero did not stimulate production of Hb C (alpha2betaC2) in fetal sheep until shortly before birth, and then only in two of six animals. Thus, factors other than erythropoietin may influence the potential for betaC globin synthesis in vivo in fetal sheep.

Animals↗
PubMed1997

Protein utilization during energy undernutrition in sheep sustained by intragastric infusion. Effect of body fatness on the protein metabolism of energy-restricted sheep.

The effect of body fat content on the protein metabolism of energy-restricted sheep has been studied in two experiments. In the first experiment, six Suffolk-cross wether sheep, three weighing about 39 kg and three of about 61 kg, were given progressively increasing amounts of casein-N from 0 to 3000 mg N/kg metabolic body weight (W0.75) daily with constant energy, 91 kJ/kg W0.75 daily, from a high-propionic acid mixture of volatile fatty acids (VFA). In the second experiment, two lean and two fat sheep of similar body weights were given progressively increasing amounts of casein with the same VFA mixture. All the animals attained a positive N balance when they were in negative energy balance. N balance was not affected by body fatness of the magnitude studied, although lean animals utilized increasing levels of standard VFA (acetate-propionate-butyrate 65:25:10, molar proportions) infusion for N accretion more efficiently than fat animals. Endogenous energy was utilized for protein accretion with an efficiency of 0.56. Supply of glucogenic VFA equivalent to 28 mmol glucose/kg W0.75 reduced fasting N excretion by 39%. Fasting heat production decreased from 335 to 300 kJ/kg W0.75 with the infusion of casein and glucogenic VFA. It is argued that fasting induces additional heat losses due to raised protein metabolism and is unsuited as a baseline for dietary assessment.

Animals↗
PubMed1987

[Consumption and ruminating behavior in sheep. 3. Experiments on infertile female sheep of different breeds with reference to feed type and feeding duration].

Ewes of the breeds merino fattening sheep, Stavropol merino and fertility hybrid were studied as to their consumption and ruminating behaviour after receiving a pelleted straw-concentrate mixture, maize silage and wilted silaged grass. During the feeding periods of 2 X 45 min or 2 X 180 min/d unlimited rations were available to the animals. With 86 min/d the sheep used the short feeding period nearly completely for feed intake. In the longer feeding period the sheep consumed 18% more feed in 161 min/d, ate more slowly, however, and ruminated somewhat less. In comparison with the straw-concentrate mixture, the silage rations were ruminated for shorter periods and less effectively, the number of ruminating movements per day and cycle was reduced, the breaks between bites became longer. The wilted grass silage stimulated ruminating even less than chopped maize silage. There were significant differences between the breeds in the ruminating frequency, which affected the number of ruminating movements per day and cycle.

Animal Feed↗
PubMed1996

Myocardial extraction of bupivacaine in anaesthetized sheep and by hearts of sheep and rats in vitro.

We observed the in vivo kinetics of bupivacaine in the cardiopulmonary system, particularly in the pulmonary artery, the upper part of the descending aorta and the coronary sinus of anaesthetized sheep, each of which received a high dose infusion into the central vein. In some experiments dilution curves were monitored for the non-extracted dye, indocyanine green. Concentrations of bupivacaine were approximately 20% lower in the aorta than in the pulmonary artery. This gradient of bupivacaine was present across the lung for 5-10 min. Concentrations of bupivacaine in the coronary venous plasma were also markedly lower than at the arterial site. Initially more than 50% of the amount of bupivacaine at the arterial site was removed by the heart. Later, the myocardial extraction ratio decreased and plateaued at a value of 0.30-0.40. At this time, concentrations of bupivacaine in the pulmonary artery were approximately 12 micrograms ml-1. Therefore, approximately 0.3-0.6 mg of bupivacaine were extracted per minute by the sheep heart in vivo. On the other hand, isolated perfused rat hearts did not substantially remove bupivacaine (2 micrograms ml-1) from the medium. Approximately one-third of 14C-bupivacaine was retained in slices of rat and sheep myocardial tissue. However, there was no evidence that metabolism played a substantial role in the cardiac kinetics of bupivacaine.

Anesthetics, Local↗
PubMed1992

Resialylation of sialidase-treated sheep and human erythrocytes by Trypanosoma cruzi trans-sialidase: restoration of complement resistance of desialylated sheep erythrocytes.

Trypanosoma cruzi trans-sialidase (TS) is a recently described enzyme which transfers alpha(2-3)-linked sialic acid from host-derived sialylated glycoconjugates to parasite surface molecules [Schenkman et al. (1991) Cell, 65, 1117]. We report here on the ability of TS to transfer sialic acid from donor sialyl-alpha(2-3)lactose to sialidase-treated sheep and human erythrocytes. Up to approximately 50% resialylation of both desialylated red cells could be attained. Resialylation of desialylated sheep erythrocytes restores their resistance to lysis by human complement. This ascribes a possible biological role for T. cruzi TS and demonstrates directly that sialic acid is solely responsible for preventing alternative pathway activation of human complement by sheep erythrocytes.

Animals↗
PubMed1993

Swaledale sheep affected by natural scrapie differ significantly in PrP genotype frequencies from healthy sheep and those selected for reduced incidence of scrapie.

PrP glycoprotein gene polymorphisms were examined in Swaledale sheep affected by natural scrapie, in healthy sheep and in Swaledales selected for low susceptibility to scrapie. The three groups differed significantly in frequencies of PrP genotypes detected by the restriction enzymes EcoRI, HindIII and BspHI, the latter being indicative of a PrP protein amino acid difference at codon 136. These frequency differences were confirmed in a single-flock study and present good evidence that scrapie susceptibility and resistance are associated with PrP gene variants in Swaledale sheep.

Age Factors↗
PubMed1982

Preliminary evaluation of 1,1-Bis (4-ethoxyphenyl)-2-nitropropane as an oviposition deterrent for the Australian sheep blowfly Lucilia cuprina, and development of methods for evaluating oviposition deterrents against sheep blowfly.

1,1-Bis(4-ethoxyphenyl)-2-nitropropane (GH74) was evaluated as an oviposition deterrent for the sheep blowfly Lucilia cuprina. In several test situations, flies laid only very few egg masses on fleece to which 0.5% GH74 had been applied, and which had been exposed in the field for up to 6 months. However, a significant number of egg masses were laid on the breech of severely scouring sheep when tested several weeks after application of GH74 at the same concentration. Procedures for evaluating oviposition deterrents against sheep blowfly are discussed.

Animals↗