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PubMed2006

Origin, genetic diversity, and population structure of Chinese domestic sheep.

To characterize the origin, genetic diversity, and phylogeographic structure of Chinese domestic sheep, we here analyzed a 531-bp fragment of mtDNA control region of 449 Chinese autochthonous sheep from 19 breeds/populations from 13 geographic regions, together with previously reported 44 sequences from Chinese indigenous sheep. Phylogenetic analysis showed that all three previously defined lineages A, B, and C were found in all sampled Chinese sheep populations, except for the absence of lineage C in four populations. Network profiles revealed that the lineages B and C displayed a star-like phylogeny with the founder haplotype in the centre, and that two star-like subclades with two founder haplotypes were identified in lineage A. The pattern of genetic variation in lineage A, together with the divergence time between the two central founder haplotypes suggested that two independent domestication events have occurred in sheep lineage A. Considerable mitochondrial diversity was observed in Chinese sheep. Weak structuring was observed either among Chinese indigenous sheep populations or between Asian and European sheep and this can be attributable to long-term strong gene flow induced by historical human movements. The high levels of intra-population diversity in Chinese sheep and the weak phylogeographic structuring indicated three geographically independent domestication events have occurred and the domestication place was not only confined to the Near East, but also occurred in other regions.

Animal Migration↗
PubMed1999

Differential effects of natural and synthetic glucocorticoids on cytochrome 17alpha-hydroxylase (P-45017alpha) and cytochrome P-450 side-chain cleavage (P-450scc) messenger ribonucleic acid in the sheep placenta.

OBJECTIVE: Our purpose was to determine differential effects of natural and synthetic glucocorticoids on cytochrome 17alpha-hydroxylase and cytochrome P-450 side-chain cleavage messenger ribonucleic acid in the sheep placenta and to determine whether feed-forward effects during labor are involved in further inducing placental cytochrome 17alpha-hydroxylase. STUDY DESIGN: Sheep underwent placement of myometrial electromyogram electrodes while they were under general anesthesia at 117 days' gestation. At 125 days' gestation either saline solution (early control animals not in labor, n = 5), 0.48 mg betamethasone during 48 hours (n = 7), 0.48 mg dexamethasone during 48 hours (n = 7), or 55 mg cortisol during a maximum of 96 hours (n = 4) was directly administered intravenously to the fetus. Necropsies were performed at 127 to 129 days' gestation. We also studied 6 ewes in spontaneous term labor at 143-147 days' gestation, 6 term control animals not in labor at 140 to 147 days' gestation, and 6 sheep in which myometrial activity was inhibited by intravenous infusion to the ewe of the selective cyclooxygenase 2 inhibitor nimesulide 9 hours after the onset of labor beginning at 147 to 148 days' gestation. Total fetal placental ribonucleic acid was analyzed by Northern blot with complementary deoxyribonucleic acid probes for cytochrome 17alpha-hydroxylase, cytochrome P-450 side-chain cleavage, and 18S ribosomal ribonucleic acid to correct for loading. RESULTS: Placental cytochrome 17alpha-hydroxylase messenger ribonucleic acid was detectable neither in term control animals not in labor nor in early control animals not in labor. Placental cytochrome 17alpha-hydroxylase messenger ribonucleic acid was induced in spontaneous term labor and all cortisol-infused sheep in labor with respect to term control animals not in labor and early control animals not in labor (P <.01). All betamethasone-infused sheep had myometrial contraction activity; however, only 4 of 7 had detectable placental cytochrome 17alpha-hydroxylase messenger ribonucleic acid. Placental cytochrome 17alpha-hydroxylase messenger ribonucleic acid was not detected in dexamethasone-infused sheep, even the 2 that had myometrial contractions. After reversal of the progression of spontaneous labor with nimesulide placental cytochrome 17alpha-hydroxylase messenger ribonucleic acid was significantly lower than the spontaneous term labor group (without nimesulide treatment). The placentas from all animals expressed cytochrome P-450 side-chain cleavage messenger ribonucleic acid, but no changes were associated with either gestational age studied (130 versus > 140 days' gestation) or glucocorticoid-induced premature labor and spontaneous term labor. CONCLUSIONS: (1) In sheep the expression of placental cytochrome 17alpha-hydroxylase is tightly associated with spontaneous term labor, and active synthesis of placental cytochrome 17alpha-hydroxylase is required during the progression of labor. (2) Cortisol is a more potent stimulator of placental cytochrome 17alpha-hydroxylase messenger ribonucleic acid in sheep than are synthetic glucocorticoids. (3) Betamethasone has a greater effect in inducing labor in sheep than does dexamethasone, possibly mediated through placental cytochrome 17alpha-hydroxylase.

Animals↗
PubMed2001

Stentless bioprosthetic heart valve research: sheep versus primate model.

BACKGROUND: The mild inflammatory response against stented bioprosthetic heart valves in the sheep model is often opposed by a more distinct response in failing human implants. With the emergence of stentless root prostheses with their significantly larger proportion of tissue interacting with the immune system of the host, a more relevant animal model than the sheep may be needed. METHODS: Valved, porcine aortic roots of 5 cm length were fixed in 0.2% glutaraldehyde and implanted in the upper descending aorta of Merino sheep (n = 5; 43+/-3 kg) and Chacma baboons (n = 5; 17+/-3 kg). After 6 weeks of tissue calcification, pannus outgrowth and inflammation were assessed by atomic absorption spectrophotometry, histologic damage scoring (0 to 3), image analysis, and transmission electron microscopy. RESULTS: The main difference between the two animal models was in aortic wall calcification (64.8+/-39.8 microg/mg in the sheep model versus 4.1+/-5.9 microg/mg in the primate model; p > 0.005). In both models, leaflet calcification was negligible (2.6+/-2.4 microg/mg in the sheep versus 2.5+/-1.9 microg/mg in the primate), and the overall extent of inflammation was comparable (1.2+/-0.8 versus 0.98+/-0.7; p = 0.18 in the sheep and the primate, respectively). Qualitatively, the sheep demonstrated a macrophage-dominated reaction whereas the inflammatory demarcation often resembled a granulocyte-dominated xenograft response in the primate. Pannus outgrowth was comparable in length (8.4+/-2.3 mm versus 9.1+/-4.3 mm proximally and 7.1+/-3.4 mm versus 7.4+/-5.1 mm distally, in the sheep and baboon, respectively; p > 0.05). CONCLUSIONS: Our results confirm the sheep as a significantly stronger calcification model for stentless aortic heart valves than the primate. Remaining antigenicity of porcine tissue as a result of incomplete cross-linking, however, elicits a distinctly stronger xenograft-type reaction in the primate model.

Animals↗
PubMed2001

Does previous protein feeding affect the response of sheep towards foods that differ in their rumen availability, but not content, of nitrogen?

The objective of the experiment was threefold: (1) to test whether an 'unlearned appetite' for dietary protein exists in sheep, (2) whether such an appetite and subsequent diet selection depend on the degree of previous protein deprivation, and (3) whether the N-source in the foods offered as choice influences diet selection. Differences in protein deprivation were achieved by feeding sheep with food either with high (HP) or low (LP) protein. Sheep were fed on Food LP, either for the same period of time as sheep on Food HP or until they reached the same live-weight (LW) as sheep on Food HP. Following the feeding regimes that induced differences in animal state, sheep were given a choice between a novel low-protein food (T) or Food T supplemented with isonitrogenous amounts with one of three nitrogen sources: urea (U), casein (C), or formaldehyde-treated casein (TFC). Diet selection measured in the short-term or over the first few days did not provide any evidence in support of an unlearned appetite for protein by sheep of different states. In fact, diet selection by all animals was characterized by an avoidance of the foods supplemented with the three nitrogen sources. This avoidance was strongest for the food supplemented with formaldehyde-treated casein. Selection of considerable amounts of supplemented foods was gradual and consistent only after animals gained experience of them, i.e. were allowed to consume a single supplemented food for a period of 7 days. Following this period, animals that had previously consumed Food LP for the same period of time as animals on Food HP selected a higher proportion of the supplemented food than the other sheep. The results support the view that there is no unlearned appetite for protein in sheep, and that control over diet selection is learned.

Animals↗
PubMed1996

Mimicry of a 21.5 kDa myelin basic protein peptide by a Maedi Visna virus polymerase peptide does not contribute to the pathogenesis of encephalitis in sheep.

Epitope mimicry is the theory that an infectious agent such as a virus causes pathological effects via mimicry of host proteins and thus elicits a cross-reactive immune response to host tissues. Weise and Carnegie (1988) found a region of sequence similarity between the pol gene of the Maedi Visna virus (MVV), which induces demyelinating encephalitis in sheep, and myelin basic protein (MBP), which is known to induce experimental allergic encephalitis (EAE) in laboratory animals. In this study, cross-reactions between sera raised in sheep against synthetic peptides of MVV (TGKIPWILLPGR) and 21.5 kDa MBP (SGKVPWLKPGR) were demonstrated using enzyme-linked immunosorbant assay (ELISA) and thin layer chromatography (TLC) immunoprobing. The antibody responses of MVV-infected sheep were investigated using ELISA against the peptides, and MBP protein, immunoprobing of the peptides on TLC plates and Western blotting against MBP. Slight significant reactions to the 21.5 kDa MBP peptide (P < 0.001) and to a lesser extent sheep MBP (P < 0.004) were detected in ELISA. The MBP peptide evoked stronger responses from more sera than the MVV peptide on immunoprobed TLC plates. On the Western blots, eight of the 23 sheep with Visna had serum reactivity to MBP. This slight reaction to MBP in MVV-infected sheep is of interest because of the immune responses to MBP evident in multiple sclerosis and EAE, but its relevance in Visna is limited since no correlation with disease severity was observed. The cell-mediated immune responses of MVV-infected sheep against similar peptides was assessed. The peptides did not stimulate proliferation of peripheral blood lymphocytes of MVV-infected sheep. Since the MVV peptide was not recognised by antibodies or T lymphocytes from MVV-infected and encephalic sheep, it was concluded that epitope mimicry of this 21.5 kDa MBP peptide by the similar MVV pol peptide was not contributing to the immunopathogensis of Visna. The slight antibody response to MBP and the MBP peptide can be attributed to by-stander effects of the immunopathology of MVV-induced encephalitis.

Animals↗
PubMed2006

The developmental changes and effect on IMF content of H-FABP and PPARgamma mRNA expression in sheep muscle.

Male Kazak sheep and Xinjiang fine wool sheep of different ages were selected to investigate the developmental changes and effect on intramuscular fat (IMF) content of heart fatty acid-binding protein (H-FABP) and peroxisome proliferator-activated receptor gamma (PPARgamma) mRNA expression in muscle. Longissimus dorsal muscle was sampled to measure IMF content; and total RNA was extracted to determine H-FABP and PPARgamma mRNA expression levels by real-time PCR. The results showed that: (1) The IMF content increased continuously with growing and showed significant differences (P<0.05) between ages in male Kazak sheep, but no such differences (P>0.05) existed in Xinjiang fine wool sheep. Furthermore, the IMF content in Kazak sheep was very much higher (P<0.01) than that of the other breed from day 30 to 90; (2) H-FABP mRNA expression level was the highest on day 2 and showed significant differences (P<0.05) between ages in male Kazak sheep as well as in Xinjiang fine wool sheep. In the former breed, the expression reached the lowest point at day 30, and then rose continuously. But in the latter breed, it declined continuously from day 2 to 90, and then increased; (3) Significant differences (P<0.05) of PPARgamma mRNA expression between ages occurred in both breeds. In male Kazak sheep, PPARgamma mRNA expression declined from day 2 to 90, while in the other breed it increased continuously from day 2 to 60, but reached the lowest level at day 90, then increased; (4) In male Kazak sheep, the mRNA expression level of H-FABP was highly positively correlated (r=0.737, P<0.01) with IMF content from day 30 to 90, but that of PPARgamma was highly negatively correlated (r=-0.835, P<0.01) with IMF content from day 2 to 90.

Animals↗
PubMed2000

Differences in pituitary cell number but not cell type between genetically lean and fat Coopworth sheep.

Coopworth sheep selected for low backfat (lean genotype) have been shown to have heavier pituitary glands than those selected for high backfat (fat genotype). This paper investigated whether this difference was due to an increase in pituitary cell number or cell size and whether the relative proportions of different pituitary cell types differed between the genotypes. In three separate trials, ram lambs aged 6 to 8 months were slaughtered and the pituitary glands were processed for stereological or immunocytochemical studies. The pituitary glands of lean genotype sheep were between 30 and 60% heavier than those of the fat sheep. Lean sheep had a significantly (P<0.05) larger cross-sectional area of the pituitary fossa (96.6 vs. 81.7 mm(2)) than fat genotype sheep. The pituitaries from lean sheep contained significantly more total cells than fat sheep (Trial 1: 290 vs. 183 million cells, P<0.01; Trial 2: 353 vs. 239 million cells, P <0.05). The volume of individual cells did not differ between the genotypes. Trial 3 showed that there was no difference between lean and fat sheep in the percentage of cells staining positive for the five pituitary hormones studied. It is concluded that the larger pituitary glands of lean compared to fat genotype sheep are a result of a nonspecific increase in the size of the whole gland through increased cell numbers, with no change in cell size or the relative proportion of different cell types.

Animals↗
PubMed1998

Ventricular fibrillation and defibrillation thresholds in sheep and dogs.

Ventricular defibrillation studies normally use dogs rather than other large species. To investigate the suitability of sheep, which are often cheaper and more readily available, we compared ventricular fibrillation and defibrillation thresholds (VFT, DFT) in sheep and dogs. A total of 12 sheep (31 +/- 5 kg) and six dogs (19 +/- 1 kg) were anesthetised with halothane. Fibrillation was induced via epicardial pacing leads, using a 1 s 50 Hz pulse. Biphasic defibrillation shocks were delivered across epicardial patches. Voltage-response curves for both fibrillation and defibrillation were generated. Logistic regression analysis was used to determine 50 and 90% probability of success for fibrillation induction and defibrillation. VFT was similar in sheep and dogs. DFT at 50% probability of success was significantly higher in sheep (369 +/- 14 V) than in dogs (299 +/- 31 V, P < 0.04) but within each species there was no correlation between heart weight and DFT. After defibrillation sheep took longer to return to sinus rhythm than dogs and electro-mechanical dissociation was observed in sheep, but not in dogs. Thus, sheep may not be an ideal model for ventricular defibrillation research but further studies of the intrinsic differences between sheep and dogs may provide insights into basic mechanisms of defibrillation.

Animals↗
PubMed2003

Metabolism of arsenic by sheep chronically exposed to arsenosugars as a normal part of their diet. 1. Quantitative intake, uptake, and excretion.

Information on the effects of long-term organoarsenical consumption by mammals is limited despite the fact that foodstuffs, especially seafood, often contain organoarsenicals at very high concentrations. Here we evaluate the intake, uptake, and excretion (urine and feces) of arsenic by sheep that live on North Ronaldsay in the Orkney Islands and naturally consume large amounts of arsenosugars through their major food source-seaweed. The sheep eat a broad variety of seaweed species, and arsenic concentrations were determined in all the species observed eaten by the sheep (5.7-74.0 mg kg(-1) dry mass). Because of preference and availability, they feed mostly on the seaweed species found to contain the highest arsenic concentrations: Laminaria digitata and Laminaria hyperborea (74 +/- 4 mg kg(-1) dry mass). To quantify the arsenic intake by the sheep, a feeding experiment reflecting natural conditions as close as possible was set up. In the feeding trial, the average daily intake of arsenic by 12 ewes was 35 +/- 6 mg (97% of water-extractable arsenic was present as arsenosugars) gained from feeding on the two brown algae. To test the possible influence of microflora on the metabolism of arsenosugars, six of the sheep were adapted to feeding on grass for 5 months before the start of the trial (control sheep), and the remaining six sheep were kept on their normal seaweed diet (wild sheep). No significant difference in seaweed/arsenic intake and arsenic excretion was found between the two groups of sheep. The arsenic excreted in the feces represents 13 +/- 10% (n = 12) of the total consumed, and on the assumption of that, the average urinary excretion is estimated to 86%.The main arsenic metabolite excreted in urine was dimethylarsinic acid (DMA(V)) (60 +/- 22%) and minor amounts of dimethylarsinoylethanol (DMAE), methylarsonic acid (MA(V)),tetramethylarsonium ion (TMA+), and arsenate (As(V)) together with seven unknown arsenic compounds were also excreted. The urinary arsenic excretion pattern showed a lag period (>4 h) before significant quantities appeared in the urine, an excretion rate that peaked between 4 and 28 h after seaweed intake and a relatively slow half-life (17 h) after end of intake.

Animal Feed↗
PubMed1997

Isolation of chromosome-specific paints from high-resolution flow karyotypes of the sheep (Ovis aries).

High-resolution bivariate flow karyotypes were obtained using fibroblast cell lines from a sheep with a normal karyotype (2n = 54), from sheep carrying Robertsonian translocation chromosomes and from sheep-hamster somatic cell hybrids. By taking advantage of the presence of chromosome polymorphisms, translocation chromosomes and sheep-hamster somatic cell hybrids, all sheep chromosomes were isolated by flow sorting. Chromosome-specific paints were generated from each sorted peak using degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR). The sheep chromosome present in each peak was identified by chromosome-specific microsatellite analysis of the DOP-PCR products and fluorescence in situ hybridization (FISH) onto DAPI-banded sheep metaphase chromosomes. The chromosome-specific DNA obtained in this study can be used for the production of genomic libraries and as a resource for mapping randomly cloned DNA sequences that will greatly aid the construction of genetic and physical maps in the sheep. The chromosome-specific paints will facilitate chromosome identification and contribute to the study of karyotype evolution in the sheep and related species.

Animals↗
PubMed1994

Cellular and ultrastructural location of angiotensinogen in rat and sheep kidney.

Recent evidence suggests the involvement of a local renin-angiotensin system in some renal actions of angiotensin II (Ang II). In this study the renal distribution of the precursor to angiotensin formation, angiotensinogen, was investigated in rats and sheep using immunohistochemistry, immunoelectron microscopy and non-isotopic hybridization histochemistry. Immunostaining for angiotensinogen was seen in proximal tubules (PCT) of both rat and sheep kidneys. In the rat the strongest immunostaining was found in the kidneys of neonatal (1 day old) rats. Staining declined after birth. Non-isotopic hybridization histochemistry using oligodeoxynucleotide probes labeled with biotin confirmed the presence of angiotensinogen mRNA expression in PCT of the rat renal cortex. Electron microscopic immunohistochemistry using antibodies raised against rat angiotensinogen showed weak staining in the adult of granule-like structures close to the apical membrane of PCT cells. In the neonatal rat kidney, angiotensinogen immunostaining was found throughout the PCT cells and was markedly stronger than that seen in adult rat kidney. In sheep, angiotensinogen immunostaining with an antibody raised against purified ovine angiotensinogen showed staining of PCT in fetal, newborn and adult sheep kidney. The strongest immunostaining seen was in fetal sheep kidney with a decline seen after birth. Reverse transcription polymerase chain reaction (RT-PCR) showed that angiotensinogen mRNA was expressed in the sheep kidney at all ages studied. Angiotensinogen expression was higher in fetal sheep kidneys (77 day and 141 day gestation) than in adult sheep kidney. In conclusion, angiotensinogen mRNA expression was detected in both rat and sheep kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensinogen↗
PubMed1970

Aspects of carnitine ester metabolism in sheep liver.

1. Carnitine acetyltransferase (EC 2.3.1.7) activity in sheep liver mitochondria was 76nmol/min per mg of protein, in contrast with 1.7 for rat liver mitochondria. The activity in bovine liver mitochondria was comparable with that of sheep liver mitochondria. Carnitine palmitoyltransferase activity was the same in both sheep and rat liver mitochondria. 2. The [free carnitine]/[acetylcarnitine] ratio in sheep liver ranged from 6:1 for animals fed ad libitum on lucerne to approx. 1:1 for animals grazed on open pastures. This change in ratio appeared to reflect the ratio of propionic acid to acetic acid produced in the rumen of the sheep under the two dietary conditions. 3. In sheep starved for 7 days the [free carnitine]/[acetylcarnitine] ratio in the liver was 0.46:1. The increase in acetylcarnitine on starvation was not at the expense of free carnitine, as the amounts of free carnitine and total acid-soluble carnitine rose approximately fivefold on starvation. An even more dramatic increase in total acid-soluble carnitine of the liver was seen in an alloxan-diabetic sheep. 4. The [free CoA]/[acetyl-CoA] ratio in the liver ranged from 1:1 in the sheep fed on lucerne to 0.34:1 for animals starved for 7 days. 5. The importance of carnitine acetyltransferase in sheep liver and its role in relieving ;acetyl pressure' on the CoA system is discussed.

Acetates↗
PubMed1987

Choline biosynthesis in sheep. Evidence for extrahepatic synthesis.

1. Choline production by various tissues of the sheep was measured by determining venous and arterial free choline concentrations in blood samples taken from various vessels in conscious multicannulated sheep. 2. Significant production of free choline occurred in the upper and lower body regions, and specifically in the heart, brain and hind-limb muscles of sheep, but there was no significant uptake or output of phosphatidylcholine across these tissues, as determined by arterio-venous differences. 3. In contrast, in the rat there were no significant arterio-venous differences in the concentrations of free choline or phosphatidylcholine across the hind-body. 4. Synthesis of phosphatidylcholine from endogenous phosphatidylethanolamine and S-adenosyl-L-[methyl-14C]methionine was measured in experiments in vitro using microsomal preparations from a variety of sheep and rat tissues. 5. The biosynthetic activity was highest in liver from sheep and rats, although the activity in sheep microsomal preparations was about one-quarter of that in rat microsomal preparations. 6. Microsomal preparations from sheep lung, kidney, gut epithelium, brain, heart and skeletal muscles also showed considerable biosynthetic activity, but in the rat the activity was virtually confined to the liver. 7. Overall, the results show a significant production of choline in extrahepatic tissues of the sheep, with skeletal muscle contributing some 60% of this extrahepatic activity. Thus the extrahepatic production of choline in the sheep, together with the extensive reutilization of bile choline, can explain the maintenance of the large endogenous body pool of choline in this species.

Animals↗
PubMed2005

Effects of a dual endothelin-1 receptor antagonist on airway obstruction and acute lung injury in sheep following smoke inhalation and burn injury.

Studies have suggested that ET-1 (endothelin-1) is associated with lung injury, airway inflammation and increased vascular permeability. In the present study we have tested the hypothesis that treatment with a dual ET-1 receptor antagonist will decrease airway obstruction and improve pulmonary function in sheep with combined S+B (smoke inhalation and burn) injury. Twelve sheep received S+B injury using the following protocol: six sheep were treated with tezosentan, an ETA and ETB receptor antagonist, and six sheep received an equivalent volume of vehicle. Physiological and morphological variables were assessed during the 48 h study period and at the end of the study. There was no statistically significant difference in the PaO2/FiO2 (partial pressure of O2 in arterial blood/fraction of O2 in the inspired gas) ratio of the tezosentan-treated animals compared with controls; however, lung lymph flow was significantly higher (P<0.05) in the treated animals. PVRI (pulmonary vascular resistance index) was significantly reduced (P<0.05) in the tezosentan-treated animals. Assessment of NOx (nitric oxide metabolite) levels in plasma and lymph showed significantly elevated (P<0.05) levels in the tezosentan-treated animals compared with levels in untreated sheep. The degree of bronchial obstruction was similar in both treated and control sheep; however, bronchiolar obstruction was reduced in sheep treated with tezosentan. Histopathologically, no difference in the degree of parenchymal injury was detected. In conclusion, administration of a dual ET-1 receptor antagonist prevented an increase in PVRI after injury and reduced the degree of bronchiolar obstruction in sheep with S+B; however, treated sheep showed higher levels of NOx and increased lung lymph flow. Tezosentan treatment was ineffective in protecting against acute lung injury in this model.

Animals↗
PubMed1999

Comparative pharmacokinetics of diminazene in lactating goats and sheep.

The pharmacokinetic aspects of diminazene aceturate were studied in lactating goats and sheep after single intravenous and intramuscular administrations of 3.5 mg/kg b.wt. Plasma and milk concentrations were determined by use of reversed phase high-performance liquid chromatography (HPLC) after ion-pair extraction. Following intravenous injection, the disposition of diminazene in goats and sheep conformed to a two-compartment model with rapid distribution and slower elimination phases. Values of (t1/2 beta) were obtained indicating a slower final disappearance of the drug from plasma of sheep (21.17 h) than in goats (16.39 h). Diminazene concentrations were maintained for more than 4 days in the plasma of goats and sheep. In both species of animals, diminazene was rapidly absorbed following intramuscular administration of 3.5 mg/kg b.wt. The peak plasma concentrations (Cmax) were 7.00 and 8.11 micrograms/ml and were attained at (Tmax) 0.92 and 1.12 hours in goats and sheep, respectively. The elimination half-life (t1/2el) of diminazene after intramuscular administration was shorter in goats (16.54 h) than in sheep (18.80 h). Systemic bioavailabilities (F%) of diminazene after intramuscular administration were 94.94% and 82.64% in goats and sheep, respectively. Diminazene could be detected in milk of goats and sheep within 10 min post-injection. Milk concentrations of the drug were lower in goats than in sheep and were detected for 5 and 6 days following both routes of administration, respectively.

Animals↗
PubMed1983

Effects of long-term ad libitum feeding on plasma lipid components and blood glucose, beta-hydroxybutyrate and insulin concentrations in lean adult sheep.

The long-term changes in plasma lipid composition and blood glucose, beta-hydroxybutyrate and insulin concentrations in experimental ad libitum fed adult Suffolk sheep were studied and compared with those of control sheep receiving a maintenance diet. The results were interpreted in relation to changes in food intake, body weight and body composition. Plasma lipid distribution was slightly influenced by the intake level and the fattening state. Compared to the maintenance diet, ad libitum feeding induced a decrease in the concentration of plasma free fatty acids (FFA); when the food intake decreased, this FFA concentration increased gradually. The fatty acid composition of the lipid fractions was subject to variation in the long-term ad libitum fed sheep. Myristic and palmitic acids in FFA, palmitoleic acid in triglycerides and linoleic acid in all the lipid fractions showed decreasing values associated with reduced food intake in the fattening sheep. Stearic and oleic acids in FFA, phospholipids and cholesterol esters increased when body weight and body fat increased and food intake decreased; they showed stable values by the end of the experiment, when food intake and body weight and composition also stabilized. Throughout the test, blood glucose concentration remained unaffected. A stable blood beta-hydroxybutyrate concentration, 2 times the control level, was observed from the 4th to the 10th experimental week in the ad libitum fed sheep (phase 1). From the 14th to the 26th experimental week (phase 2), decreased values were associated with increasing body weight and decreasing food intake. From the 30th week on (phase 3), beta-hydroxybutyrate concentration stabilized at a level 50 p. 100 higher than in the control sheep. During the first 6 weeks of ad libitum feeding, the experimental sheep achieved the same plasma insulin concentration as the control sheep. Thereafter a 30-fold increase was noted. Moreover, fluctuations of between 20 and 1 600 microU/ml were observed in fattening phases 2 and 3. This experiment demonstrated that feeding adult sheep ad libitum induces complex interrelationships between food intake and fattening state on the one hand and several blood substances on the other. Other experiments are needed to clarify these interrelationships.

3-Hydroxybutyric Acid↗
PubMedDate not supplied

The effect of Saccharomyces cerevisiae and Aspergillus oryzae on the digestion of the cell wall fraction of a mixed diet in defaunated and refaunated sheep rumen.

The objective of this study was to determine the effect of two probiotics, Saccharomyces cerevisiae (SC) and Aspergillus oryzae (AO), without their culture medium, on the digestion of plant cell wall components in sheep that had been successively defaunated and refaunated. Six sheep fitted with large rumen cannulae were used to study 1) defaunated sheep with no probiotic, 2) defaunated sheep with SC or AO, 3) refaunated sheep with no probiotic, 4) refaunated sheep with SC or AO. The apparent digestibility of the plant cell walls was not altered (P > 0.05) by the probiotics in defaunated sheep but was increased (P < 0.05) with SC (+16%) in refaunated sheep. Simultaneously, SC stimulated the growth of the protozoal population in the rumen. As noted in most previous experiments, the positive effect of the presence of protozoa on plant cell wall digestion (P < 0.001) was confirmed here. The effect (P > 0.05) of SC or AO on in situ ADF digestion was either not significant or negative in defaunated rumens, whereas it became positive in refaunated rumen after a residence time of 12 h. The improvement of in situ ADF digestion due to the presence of protozoa was significant (P < 0.05 for NDF; P < 0.001 for ADF). However, we could not determine whether this was a direct effect of protozoa or an indirect effect operating via bacteria. The limits of the nylon bag technique for evaluating the microbial activity are discussed in relation to the ability of protozoa to enter and grow in the bags, and the pH regulation inside the bags. The pH values below 5.5 noted inside the bags can significantly alter the bacterial and protozoal populations and limit the validity of the technique. SC increased (P < 0.05) the specific activity of CMCase and xylanase of the solid-adherent bacteria (SAB) isolated from the rumen digesta of refaunated sheep. Stimulation of both the bacterial activity and protozoa numbers could explain the positive effect of SC on cell wall digestion in the rumen since the modelling of marker excretion in faeces showed that the ruminal mean retention time of hay measured from the model of Danhoa et al. was not modified (P > 0.05) by either refaunation or the presence of probiotics. AO increased (P < 0.05) the total retention time of the solid particles in the whole digestive tract and increased the ruminal liquid volume in the refaunated animals but it had no effect on the protozoa population or on the polysaccharidase activity of the SAB, which could explain the absence of effect of AO on the total digestibility of plant cell walls. Both probiotics decreased the liquid turnover in defaunated rumens (P < 0.05) but neither had any effect (P > 0.05) on this parameter after refaunation. The improvement of plant cell wall degradation in the whole digestive tract is probably due to a stimulation of digestion at the rumen level as indicated by the higher activity of the SAB in rumen digesta and the growth of protozoa.

Animal Feed↗
PubMed2001

Onset and distribution of tissue prp accumulation in scrapie-affected suffolk sheep as demonstrated by sequential necropsies and tonsillar biopsies.

Tonsillar biopsies (single or multiple) or necropsies, or both, were performed on sheep taken from a Suffolk flock in which frequent cases of scrapie had occurred over a period of several years. Clinically affected sheep of the susceptible PrP(AQ/AQ)genotype had widespread disease-specific PrP accumulation in the central nervous system (CNS), lymphoreticular system and peripheral ganglia. In nine healthy PrP(AQ/AQ)Suffolk sheep between 4 and 7 years of age, PrP could not be demonstrated post mortem in any of the lymphoreticular tissues, or in the peripheral ganglia or CNS. Tonsillar biopsies taken from animals of the resistant PrP(AR/AR)and PrP(AR/AQ)genotypes at age 3, 8, 14, 20 or 26 months did not show PrP accumulation. Disease- specific PrP accumulation in tonsillar biopsies from PrP(AQ/AQ)sheep was not seen in 20 animals aged 3 months, but was found in two of 10 animals at age 8 months and in eight of 10 animals at age 20 months. The numbers of PrP-positive tonsillar biopsies obtained from sheep previously biopsied on more than one occasion was greater than the number of positive tonsils obtained from other susceptible sheep of comparable ages. The earliest disease-specific PrP accumulation seen was in tingible body macrophages within germinal centres and only later was it detected in cells resembling follicular dendritic cells. Fourteen PrP(AQ/AQ)sheep examined post mortem at up to 17 months of age and which had not previously been biopsied or were biopsied only once had no CNS or tonsillar PrP accumulations. Two of these sheep subjected to necropsy at 14 months had PrP accumulation in lymphoreticular tissue, where it was confined to the mesenteric lymph nodes. In susceptible sheep, only low levels of immunohistochemically detectable PrP were present in a minority of follicles from tonsillar biopsies of young lambs, but by 14 months of age widespread PrP accumulation, affecting many or even all follicles, was present. Although clinical cases had widespread PrP accumulations in viscera, susceptible survivors had no such accumulations in tissues of the lymphoreticular system, peripheral nervous system or CNS, suggesting that some animals were not exposed to infection or were exposed to a non-infectious dose.

Animals↗