Responsiveness of prehaemolytic copper poisoning in sheep from a specific pathogen-free environment to a relatively high dose of tetrathiomolybdate

Efficacy of ammonium tetrathiomolybdate (3.4 mg/kg LW, TTM(3.4)) was monitored in nine, specific pathogen-free sheep with mild-to-severe, prehaemolytic copper poisoning (pre-HCP). Five sheep were given three subcutaneous injections over seven days and four began a shorter, five-day course four days later. Plasma bile acid (BA) and glutamate dehydrogenase (GDH) had fallen significantly after six days but BA briefly rose again between days 10 to 18. Aspartate aminotransferase (AST), δ-glutamyl transferase (GGT) were later to decline but presented little evidence of hepatotoxicity by day 45. Erythrocyte superoxide dismutase (ESOD) was rapidly inhibited, activities falling by 65 per cent within three days and taking 25 days to recover. Trichloroacetic (TCA)-insoluble copper increased by 6 to 8 μmol/l after three days but had largely disappeared by day 18. Six lambs had become hypercupraemic by day 18 due to a rise in TCA-soluble Cu. ESOD activity fell again by 188±29.5 U/gHb between days 25 and 45 but had largely recovered by day 62. TTM(3.4) gave better control of hepatotoxicity than TTM(1.7) had done in more severely affects cohorts but at the expense of greater inhibition of ESOD. Treatment of pre-HCuP should rely more on reducing copper absorption until more is known of the side effects of TTM on cuproenzymes.     

Effects of clonidine and idazoxan on tetrathiomolybdate-induced copper and lysosomal enzyme excretion into sheep bile

This study investigated the effects of intravenous (IV) administration of tetrathiomolybdate (TTM), and α(2)-adrenergic agonist clonidine (CLO) and α(2)-antagonist idazoxan (IDA), alone or in combination with TTM, on sheep fed low (LCu) and high (HCu) copper diets. Effects on bile flow, biliary Cu concentration and excretion, plasma Cu concentration, and lysosomal enzyme β-glucuronidase (β-GLU) activity in bile and plasma were determined. Tetrathiomolybdate alone or with CLO or IDA significantly enhanced biliary Cu excretion most likely by removing Cu from hepatocyte lysosomes as evidenced by a significant increase in β-GLU enzyme activity in bile. A significant increase in plasma β-GLU concentration occurred only in sheep treated with CLO in combination with TTM. Because of the lytic nature of the lysosomal enzymes, caution is advocated in use of drugs, especially α(2)-adrenergic agonists, to further enhance TTM-induced biliary Cu excretion in the treatment of chronic Cu poisoning in sheep.     

The effects of ammonium tetrathiomolybdate intake on tissue copper and molybdenum in pregnant ewes and lambs

Pregnant ewes (d 32 of gestation) were allocated to three treatments and given intraruminal controlled-release devices designed to deliver 0, 20 or 60 mg diammonium tetrathiomolybdate (TTM) per day. Ewes given 20 or 60 mg TTM/d also received an oral drench of 120 or 360 mg TTM twice weekly commencing on d 86 of gestation. Liver and kidney samples were taken from lambs 48 h after birth and from ewes on d 18 postpartum. Trichloroacetic acid soluble Cu, ceruloplasmin and superoxide dismutase activities in the plasma of ewes were decreased (P less than .05) by TTM. Liver Cu concentrations were decreased (P less than .05), but kidney Cu concentrations increased (P less than .05) by 16-fold in ewes given the higher dose of TTM. Liver and kidney Mo concentrations were elevated (P less than .05) 9- and 30-fold, respectively, in ewes given TTM. Plasma glucose concentrations in ewes were decreased (P less than .05) by the highest level of TTM treatment. Lambs of ewes given TTM had a fivefold increase (P less than .05) in liver Mo concentration, but kidney Mo concentration was not affected (P greater than .05) and liver Cu concentration was reduced (P less than .05). In ewes, Mo apparently caused Cu to be mobilized from the liver and a Cu and Mo complex accumulated in the kidney. Some Mo crossed the placenta, but only limited Mo accumulated in the fetal livers. When given to pregnant ewes, TTM reduced liver Cu levels in the lambs but did not affect the concentration of Cu in colostrum.     

Temporal patterns and quantification of excretion of Mycobacterium avium subsp paratuberculosis in sheep with Johne's disease

OBJECTIVES: To determine the frequency of excretion of Mycobacterium avium subsp paratuberculosis in Merino sheep with Johne's disease and to quantify excretion in a group of Merino sheep. DESIGN: A pen and laboratory experiment. PROCEDURE: Seven sheep selected from an affected flock on the basis of acid-fast bacilli in the sheep's faeces were housed and total daily faecal output was collected, weighed and subjected to culture for M avium subsp paratuberculosis. An end-point titration method was used to enumerate viable M avium subsp paratuberculosis in a 15 day pooled sample from five sheep that had acid-fast bacilli in their faeces while housed. RESULTS: Four sheep with subclinical multibacillary Johne's disease excreted M avium subsp paratuberculosis each day for 11 days of cultural observation. A further three sheep were intermittent excreters but lacked other evidence of infection with M avium subsp paratuberculosis. The average number of viable bacteria excreted was 1.09 x 10(8) per gram of faeces while total daily excretion was 8.36 x 10(10) viable M avium subsp paratuberculosis per sheep. Examination of faecal smears stained with Ziehl Neelsen was an unreliable means of assessing daily excretion in individual animals except in those with severe lesions. CONCLUSION: Excretion of M avium subsp paratuberculosis in Merino sheep with multibacillary Johne's disease occurred daily, proving that environmental contamination can be continuous on farms with endemic ovine Johne's disease. Faecal culture is a useful method for detecting infection as it does not appear to be affected by the timing of collection of a sample from sheep with multibacillary disease however, to maximise the sensitivity of disease surveillance using faecal culture, sampling rates should be adjusted to take account of the proportions of multibacillary and paucibacillary cases.     

Enhancement of tetrathiomolybdate-induced biliary copper excretion in sheep by general anaesthesia and the effect on copper excretion in urine and bile

To determine whether copper removed from the liver by tetrathiomolybdate (TTM) but not excreted in bile, is excreted in saliva or urine, the effect of an intravenous injection of 100 mg of TTM, as ammonium tetrathiomolybdate, on copper excretion by these routes was measured in conscious sheep and sheep maintained under general anaesthesia. During 4.5 hours the total amount of copper excreted in bile in the untreated, conscious animal was 0.52 +/- 0.04 mumols (mean +/- SE). A dose of 100 mg TTM increased excretion by an average of 11.7-fold to 6.06 +/- 0.29 mumols. Under halothane or barbiturate general anaesthesia copper excretion was increased 3.4-fold to 1.78 +/- 0.30 mumols. In anaesthetised sheep 100 mg TTM produced a 40.7-fold increase to 21.18 +/- 0.95 mumols. Neither anaesthesia nor TTM caused any increase in copper excretion in saliva or urine.     

Long-term observation of subclinical chronic copper poisoning in two sheep breeds

Fourteen castrated male sheep of two breeds, the Mutton Merino (MMB) and Blackhead Suffolk cross breed (BSC), were exposed to an oral copper (Cu) intake of 3.7 mg/day per kg body weight for 84 days (high Cu group, HCu), and 11 castrated male sheep received a daily oral Cu intake of 0.16 mg/day per kg body weight (controls). Liver Cu concentration was measured in liver biopsies until 2.7 years after Cu overdose. Haematologic parameters, plasma Cu, enzymes and metabolites were analysed and post-mortem examinations were carried out. No haemolytic crises occurred. The highest liver Cu concentrations (133-677 mg/kg wet weight) were measured in HCu sheep around day 110 with significantly higher values in BSC than in MMB. The very slow decreases of liver Cu concentration of HCu sheep after day 215 showed individual half-life periods of 175 +/- 91 days. A progressive Cu retention in the liver of HCu sheep during Cu supplementation indicates strong Cu binding and storage in the liver. High values of glutamate dehydrogenase (20-940 U/l) measured frequently until day 700 and a diminished plasma clearance of bromosulphthalein as well as pathohistological findings of focal liver necrosis confirm the markedly chronic character of Cu poisoning.     

Rates of change in liver copper concentration in cattle given a copper-deficient diet,with or without pre-treatment with tetrathiomolybdate,for evaluation of two parenteral copper supplements

AIM: To minimise the impact of initial variation in liver copper (Cu) on assessments of Cu supplements for cattle in depletion/repletion experiments.

METHODS: Efficacy of two Cu injections was assessed with 18 calves, weighing 200–250 kg, given a Cu-deficient barley diet, containing 4.1 mg Cu/kg dry matter (DM) and added molybdenum (3 mg/kg) and sulphur (3 g/kg). Initial liver biopsy Cu ranged from 3.15–14.17 mmol/kg DM and nine calves with the highest values were given three subcutaneous injections of 235 mg tetrathiomolybdate (TTM) after 42–46 days depletion to lower liver Cu. Untreated (L) and TTM-treated (H) calves were ranked separately for liver Cu after 50 days depletion and allocated to one of three treatments: 100 mg Cu given subcutaneously as CuCaEDTA in either a paraffin (CuP) or aqueous base (CuA) after 56 days depletion (Day 0) or no injection (O). Thereafter, plasma and liver biopsy Cu were measured every 2–4 weeks for 16 weeks. Responses in liver Cu to Cu injections were compared with and without log_e transformation and by linear regression.

RESULTS: Prior to Cu injection, the fractional decline in liver Cu concentration (FDLCu) after 50 days depletion was 0.64 (SE 0.066) and 0.80 (SE 0.090) in H and L calves, respectively (p=0.09) and mean liver Cu did not differ on Day ?6 (6.65 (SE 0.516) and 4.91 (SE 0.681) mmol/kg DM, respectively). Mean plasma Cu was higher in H than L calves on Day 0 (16.6 (SE 0.52) and 13.3 (SE 0.49) μmol/L, respectively (p<0.001)). Rates of decline in log_e liver Cu between Days 0–84 in treatments L and H were: 0.0138 and 0.0071 for Groups O; 0.0033 and 0.0016 for Groups CuP; 0.0073 and 0.0049 for Groups CuA (pooled SE 0.0014) mmol/kg DM/day, respectively. Between Days 84–114, FDLCu was uniformly high across experiments and groups (0.59 (SE 0.042)). Cu injections did not affect plasma Cu, which remained 3.1 (SE 0.41) umol/L higher in Experiment H than in L (p=0.017).

CONCLUSIONS: The use of rates of change in liver copper concentrations improved the assessment of efficacy for two parental copper supplements and that of pre-treatment with tetrathiomolybdate, which, contrary to expectation, slowed Cu turnover by mechanisms that remain unclear.     

Malignant catarrhal fever-like disease in sheep after intranasal inoculation with ovine herpesvirus-2.

A malignant catarrhal fever (MCF)-like disease was induced experimentally in 3 sheep after aerosol inoculation with ovine herpesvirus-2 (OvHV-2). Each of 3 OvHV-2-negative sheep was nebulized with 2 ml of nasal secretions containing approximately 3.07 X 10(9) OvHV-2 DNA copies from a sheep experiencing an intensive viral-shedding episode. Ovine herpesvirus-2 DNA became detectable by polymerase chain reaction in the peripheral blood leukocytes of all 3 sheep within 3 days, and all 3 seroconverted between 6 and 8 days postinfection (PI). The sheep developed clinical signs, with copious mucopurulent nasal discharge and fever around 14 days PI. One of the 3 clinically affected sheep was euthanized at 18 days PI. Major lesions at necropsy were multifocal linear erosions and ulcers in mucosa of the cheeks, tongue, pharynx, and proximal esophagus and mild disseminated pneumonia. Microscopically, there was extensive moderate superficial histiocytic-lymphocytic rhinitis with epithelial dissociation and degeneration. Moderate multifocal histiocytic bronchointerstitial pneumonia was associated with loss of terminal bronchiolar epithelium. Lymphocytic vasculitis was present only in the lung. The remaining 2 sheep recovered clinically, approximately 25 days PI. The study revealed that clinical signs and lesions resembling MCF can develop when uninfected sheep are exposed to a high dose of aerosolized OvHV-2.     

Enhancement of tetrathiomolybdate-induced copper excretion in bile of sheep by the alpha 2-agonistic action of xylazine

The effect of intravenous doses of cortisol and xylazine on the quantity of copper excreted in response to 100 and 200 mg doses of tetrathiomolybdate (TTM) was studied in seven sheep. Cortisol alone produced a non-significant 1.4-fold increase and had no enhancing action on the response to TTM. Xylazine produced a significant 2.25-fold increase, doubled the quantity of copper excreted in response to both doses of TTM and reduced bile flow by approximately 35 per cent. The alpha 2 antagonist, idazoxan, prevented both the latter effects showing that they were due to xylazine's alpha 2-agonistic action. It is suggested that the combination of an alpha 2-agonist with the intravenous injection of TTM in the treatment of acute copper toxicity in sheep could reduced by 50 per cent the amount of molybdenum needed.     

Evaluation of a commercially available molybdate formulation and zinc oxide boluses in preventing hepatic copper accumulation and thus enzootic icterus in sheep

The efficacy of a molybdate formulation and a zinc oxide bolus as prophylactic agents for enzootic icterus was evaluated in sheep. Before copper loading, liver biopsies were performed on 12 male, 6-month-old, Mutton Merino sheep to determine hepatic copper (Cu) and zinc (Zn) concentrations. The animals were restrictively randomised according to liver copper concentrations to 3 treatment groups (n = 4) to achieve similar mean liver copper concentrations per group. All sheep received 4 ml/kg of a 0.5 % aqueous solution of CuSO4 5H2O intraruminally 7 days per week for 10 weeks. On Day 0 the sheep in the Mo-group were injected subcutaneously with 42 mg molybdenum (Mo) contained in a commercial molybdate formulation. The animals in the Zn-group each received a zinc oxide bolus, containing 43 g zinc oxide, via a rumen cannula. Treatment was repeated on Day 42. Four animals served as untreated controls. Urinary copper excretion, plasma copper concentration, haematocrit and glutamate dehydrogenase (GLDH) activity were determined throughout the trial. The animals were sacrificed after 10 weeks and liver samples were submitted for histopathological examination. Liver and kidney copper and zinc concentrations were determined. Neither the molybdate treatment nor the zinc oxide boluses prevented hepatic copper accumulation. The urinary copper excretion, plasma copper concentration, haematocrit and GLDH activity were not significantly different (P > 0.05) from the controls.     

Antigenic profiles of recombinant proteins from Mycobacterium avium subsp. paratuberculosis in sheep with Johne's disease

Methods to improve the ELISA test to detect Mycobacterium avium subsp. paratuberculosis have been explored over several years. Previously, selected recombinant proteins of M. avium subspecies paratuberculosis were found to be immunogenic in cattle with Johne's disease. In the present study, antibody responses of infected and healthy sheep were evaluated using 18 purified recombinant proteins in an ELISA-based format for the serodiagnosis of ovine paratuberculosis. These selected recombinant proteins represent heat shock proteins, hypothetical proteins and cell surface proteins of M. avium subsp. paratuberculosis. Whereas, Map0862 (a gene uniquely present in M. avium subspecies paratuberculosis) and Map3786 encoded protein solicited the strongest antibody response in infected sheep. The protein encoded by Map2116c showed the weakest antibody response among the animals tested. Although none of the recombinant proteins detected all 11 infected sheep singly, antibodies to Map0862 were detected in 9 of 11 (81%) infected sheep. Furthermore, ovine responses to these selected antigens were assessed temporally over the course of 1 year during which we found a spiking effect rather than an incremental increase of antibody reactivity. This study evaluated multiple M. avium subsp. paratuberculosis recombinant proteins in an ELISA-based format for sheep.     

Plasma kinetics and efficacy of oral megazol treatment in Trypanosoma brucei brucei-infected sheep

Experimentally infected sheep have been previously developed as an animal model of trypanosomosis. We used this model to test the efficacy of megazol on eleven Trypanosoma brucei brucei-infected sheep. When parasites were found in blood on day 11 post-infection, megazol was orally administered at a single dose of 40 or 80mg/kg. After a transient aparasitaemic period, all animals except two relapsed starting at day 2 post-treatment, which were considerated as cured on day 150 post-treatment and showed no relapse after a follow-up period of 270 days. In order to understand the high failure of megazol treatment to cure animals, a kinetic study was carried out. Plasma concentrations of megazol determined, by reverse-phase high-performance liquid chromatography at 8h post-treatment in these animals, were lowered, suggesting slow megazol absorption, except in cured animals. However, megazol plasma profiles in uninfected sheep after a single oral dose of megazol showed a fast megazol lowered absorption associated with a short plasma half-life of drug. Inter-individual variation of megazol pharmacokinetic properties was also observed. These findings suggested that the high failure rates of megazol treatment were related to poor drug availability after oral administration in sheep. In conclusion, megazol could cure sheep with T. b. brucei infection but oral administration was not an effective route.     

Intrauterine and transmammary transmission of Mycobacterium avium subsp paratuberculosis in sheep

OBJECTIVE: To investigate intrauterine infection of foetuses with Mycobacterium avium subsp paratuberculosis and the presence of infection in mammary secretions of sheep. DESIGN: A study of 142 late-pregnant ewes and their foetuses from two heavily infected flocks. PROCEDURE: Infection of ewes was determined at necropsy by histopathology and culture of tissues and mammary secretions. Antemortem tests (clinical assessment, faecal culture and serology) were also applied. Foetuses from 59 infected ewes and 47 apparently uninfected ewes were examined by culture and histopathology. RESULTS: Five of five ewes with clinical ovine Johne's disease had infected foetuses. Only one of 54 subclinically affected ewes, and none of 47 uninfected ewes had an infected foetus. M a paratuberculosis was cultured from mammary secretions or mammary glands of only two of 76 ewes, both of which were clinical cases and had infected foetuses. CONCLUSION: Although intrauterine or transmammary transmission of Mycobacterium avium subsp paratuberculosis may occur frequently in clinically affected sheep, these are less common in subclinically infected ewes. Therefore these modes of transmission are unlikely to compromise existing control programs for ovine Johne's disease on most farms, especially if programs include the immediate culling of clinically affected sheep.     

Copper poisoning of sheep after ad libitum supplementation of rations by a mineral feed

Within 8 weeks 22 of 400 sheep died with symptoms of Cu intoxication. In the liver of 2 dead sheep Cu contents of 491 and 830 mg/kg dry matter were found. The concentration of copper in the concentrate and other feedstuffs (grass, hay, straw, kale, dried sugar beet pulp) could not explain the development of Cu-toxicosis. The mineral-vitamin-supplement contained 86.7 mg Cu/kg. Obviously the Cu intoxication of previously Cu loaded sheep was provoked by offering the mineral supplement ad libitum (with intervals of 3-4 days), the intake of this mixture reached values up to 400 g/animal and day. By renunciation of mineral supplements in the same flock 7 months later lambs died due to Cu deficiency (Cu content in the liver: 13-14 mg/kg dry matter).     

An evaluation of the effect of clotting on the recovery of copper from caprine blood

In the goat, diagnosis of copper (Cu) deficiency is often based on measurement of Cu in serum or plasma. Previous research in cattle and sheep has shown that these values are not interchangeable, but data for goats have not been published. Paired serum and heparinised plasma samples taken from 119 goats in eight herds were tested for Cu concentration. Plasma and serum Cu were significantly correlated (r=0.95). On average serum Cu was 3.5 μmol/L lower than plasma Cu, but this difference was related to Cu status (r=0.45). Mean serum Cu concentration was 83% of plasma Cu, with the 95% limits of agreement ranging from 66% to 100%. Similar to cattle and sheep, individual variability in Cu loss during clotting is too great for serum Cu to be used as a measure of Cu status in goats.     

The effect of dietary molybdenum on hypocupraemic ewes treated by subcutaneous copper

An attempt has been made to assess the importance of systemic sites of interaction from the effect of dietary molybdenum (Mo) on the protection afforded by a single sc injection of copper (Cu) to 29 initially hypocupraemic 5-year-old ewes, maintained on a low Cu diet. They were fed a diet of 1 kg/day containing 1.3 mg of Cu/kg supplemented with sodium sulphate which provided 1.7 gm of sodium per kg. Group A was given no further supplement. Group B was given added Mo, 25 mg/kg. Group C was given added Cu, 10 mg/kg. After 7 months, several animals in each group were injected sc with a single dose of 46.5 mg of Cu in the form of copper calcium edetate (Coprin). Blood samples were taken at intervals from the injected ewes over a 250-day period. All ewes were mated after 12 months on the diet. Injected ewes were approaching the 4th month of gestation when the last blood sample was taken at 250 days. Total Cu in plasma was determined by atomic absorption spectometry. Direct reacting Cu in plasma, cerulosplasmin oxidase activity, and hemoglobin were also estimated. Plasma Cu concentrations had increased to normal levels in 14 days in Group A after the Cu injections. Group B animals showed a greater increase, mean values exceeding those of Groups A and C, between Days 28-129 (p less than .01). Plasma Cu levels declined in ewes not given supplementary Cu after the 177th day. The final values for Groups A and B were similar to those found before injection. The direct reacting Cu in each group was increased after 7 days (p less than .05). This effect was most marked in the Mo supplemented ewes (Group B). The effect of Mo persisted until the final bleeding. Direct reacting Cu was only a minor part of the early response in total plasma copper of Group B ewes. Dietary Mo did not inhibit the incorporation of injected Cu into ceruloplasmin. The Mo-supplemented ewes were in poorer condition than copper-supplemented ewes. All groups gained in weight after the injections. The sc injection of Cu at 5 months prior to mating imporved fertility in Groups A and B. There was no evidence that dietary Mo impa ired the metabolism of parenteral Cu. However, it is known to deplete r uminants of Cu when the diet provides the only source of Cu. It is ther efore thought that the site of the Cu with Mo interaction is in the gut. If infertility due to Cu deficiency is suspected in a flock, an injection of Cu immediately prior to mating may improve conception rate and provide sufficient Cu to reduce the incidence of swayback.     

An assessment of the safety of copper heptonate for parenteral therapy in sheep

OBJECTIVE: To investigate any adverse effects of an intramuscular injection (i.m.) of copper heptonate (CuHep) in sheep. PROCEDURE: Merino wethers about 9 months old were retained in pens and given 1 or 2 mg Cu/kg body weight as CuHep or no Cu treatment. Sheep were weighed and samples of blood for haematology, Cu and enzyme assay and tissues for Cu and Fe assay were collected before and at intervals over 21 days after treatment. RESULTS: CuHep was removed from the injection site within 7 days of treatment and most of it was retained in the liver. Wethers had adequate liver Cu reserves before treatment and the higher dosage of CuHep raised liver Cu to values associated with Cu toxicity. No clinical signs of Cu toxicity were evident. Transient increases in plasma activity of the liver enzyme glutamate dehydrogenase suggested mild liver necrosis due to CuHep, but there was no histopathological evidence of liver necrosis 7 days after treatment. CONCLUSIONS: I.m. injection of Cu as CuHep appears to be readily transferred to the liver. No significant necrosis is caused at the injection site.     

Superoxide production in phagocytes obtained from Mycobacterium marinum-stimulated goldfish (Carassius auratus) that were exposed to copper.

OBJECTIVE: To investigate the effects of copper exposure and recovery from copper toxicosis on the nonspecific immune response in Mycobacterium marinum-inoculated goldfish. ANIMALS: Goldfish (Carassius auratus) with a mean weight of 33.5 g. PROCEDURE: Superoxide (O2-) production was measured in fish 2 to 6 weeks after injection with phosphate-buffered saline (PBS) solution or M marinum (10(2) to 10(7) colony-forming units [CFU]/fish). Then, paired groups of fish were injected with PBS solution or 10(4) CFU of M marinum and exposed to copper (100 microg/L) for 7 days or for 4 days with 3 days of recovery. One paired group not exposed 14 days later to copper served as control fish. Phagocyte production of O2-was measured by use of the nitroblue tetrazolium reduction assay. Inflammation and bacterial colony counts were determined by use of routine histologic and microbiologic procedures. RESULTS: Superoxide production achieved a maximal response 2 to 4 weeks after M marinum inoculation. Compared with control fish, O2- production increased in the groups exposed to copper but then decreased in the exposed groups that were allowed to recover. Superoxide response and peritoneal inflammation were greater in M marinum-inoculated groups than in non-inoculated groups. CONCLUSIONS: Copper exposure and inoculation with M marinum increased O2- production, whereas recovery after exposure decreased O2- production, even in fish that were immunostimulated by M marinum. CLINICAL RELEVANCE: When the antimicrobial oxidative response is suppressed after copper exposure, steps should be taken to avoid imposing additional stress and minimize the possibility of resurgent or secondary pathogenic infections.     

高钼条件下日粮添加赖氨酸铜对绵羊铜代谢及粗饲料消化能力的影响

选用4只安装永久性瘤胃瘘管的杂一代羯羊,采用拉丁方设计,研究4种铜添加水平(0,6,12和18 mg/kg)和4种硫添加水平(0%,0.05%,0.10%和0.15%)在高钼(12.55 mg/kg)条件下对绵羊铜代谢及粗料消化能力的影响。结果表明:铜的添加可以显著地(P<0.05)提高血浆和三氯乙酸(TCA)溶解铜浓度;TCA溶解铜浓度随硫水平的提高极显著(P<0.01)降低,TCA不溶性铜极显著(P<0.01)提高。综合上述结果,赖氨酸铜是绵羊理想的有机饲料铜源。     

Lymphocyte blastogenesis, complement fixation, and fecal culture as diagnostic tests for paratuberculosis in North American wild ruminants and domestic sheep

The efficacy of the lymphocyte blastogenesis and complement-fixation tests and fecal culture for detection of Mycobacterium paratuberculosis infection was assessed in bighorn sheep (Ovis canadensis), elk (Cervus elaphus nelsoni), mule deer (Odocoileus hemionus), white-tailed deer (O virginianus), bighorn X mouflon (O musimon) hybrid sheep, and domestic sheep. Spontaneously infected bighorns were tested at the time of capture; experimentally infected animals were tested monthly for 12 months or periodically for 36 months. Lymphocyte blastogenesis tests were conducted with peripheral blood mononuclear cells and protein antigens of M avium, M bovis, and M paratuberculosis. Best diagnostic results were obtained when M avium purified-protein derivative was used as antigen and 20% bovine fetal serum was incorporated in the culture medium; a positive test was defined as a stimulation index greater than or equal to 3.5. Test sensitivity and specificity, respectively, were 82% and 94% in hybrid sheep and were 72% and 100% in domestic sheep. Sensitivity and specificity, respectively, were 39% and 94% in elk and 53% and 92% in deer. When infection was determined in spontaneously infected bighorns by culture of M paratuberculosis and/or the presence of acid-fast bacilli in characteristic microscopic lesions, sensitivity was 75% and specificity was 87%. Fecal cultures and the complement-fixation tests seldom correctly identified infected animals.